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Full text of "Journal of the Society of Motion Picture and Television Engineers"

From the collection of the 



o Prejinger 
v JLjlbrary 

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San Francisco, California 
2007 




/-^ ~N^ 

JOURNAL OF THE 
SOCIETY OF 

MOTION PICTURE 

AND 

TELEVISION 

ENGINEERS 




THIS ISSUE IN TWO PARTS 
Part I, December 1953 Journal Part II, Index to Vol. 61 



VOLUME 61 
July December 1953 



SOCIETY OF MOTION PICTURE 
AND TELEVISION ENGINEERS 

40 West 40th St., New York 18 



CONTENTS Journal 

Society of Motion Picture and Television Engineers 

Volume 61 : July December 1953 

Listed below are only the papers and major reports from the six issues. See the 
Volume Index for those items which generally appear on the last few pages of each 
issue: Standards, Society announcements (awards, Board meetings, committee 
reports, conventions, engineering activities, membership, nominations, section 
activities), book reviews, current literature, letters to the Editor, new products and 
obituaries. 

July 

Correction of Frequency-Response Variations Caused by Magnetic- 
Head Wear KURT SINGER and MICHAEL RETTINGER 1 

1 6mm Motion- Picture Theater Installations Aboard Naval Vessels . . 

PHILIP M. COWETT 8 
A First-Order Theory of Diffuse Reflecting and Transmitting Surfaces 

ARMIN J. HILL 19 

Photography of Motion JOHN H. WADDELL 24 

The BRL-NGF Cinetheodolite 

SIDNEY M. LIPTON and KENNARD R. SAFFER 33 
16mm Projector for Full-Storage Operation With an Iconoscope Tele- 
vision Camera EDWIN C. FRITTS 45 

Television Test Film: Operating Instructions 52 

August Part I 

Image Gradation, Graininess and Sharpness in Television and Motion- 
Picture Systems Part III : The Grain Structure of Television 

Images OTTO H. SCHADE 97 

Photographic Instrumentation of Timing Systems . . A. M. ERICKSON 165 
The M-45 Tracking Camera Mount .... MYRON A. BONDELID 175 
Fundamental Problems of Subscription Television: the Logical 

Organization of the Telemeter System 

Louis N. RIDENOUR and GEORGE W. BROWN 183 
Closed-Circuit Video Recording for a Fine Music Program .... 

W. A. PALMER 195 

ii Contents: Journal of the SMPTE Vol. 6 1 



August Part II 

Foreword Screen Brightness Symposium W. W. LOZIER 213 

New Photoelectric Brightness Spot Meter 

FRANK F. CRANDELL and KARL FREUND 215 
Recent Developments in Carbons for Motion-Picture Projection . . . 

F. P. HOLLOWAY, R. M. BUSHONG and W. W. LOZIER 223 
Picture Quality of Motion Pictures as a Function of Screen Luminance 

LAWRENCE D. CLARK 241 
Optimum Screen Brightness for Viewing 1 6mm Kodachrome Prints . 

L. A. ARMBRUSTER and W. F. STOLLE 248 

Effects of Stray Light on the Quality of Projected Pictures at Various 
Levels of Screen Brightness RAYMOND L. ESTES 257 

September Part I 

The Development of High-Speed Photography in Europe 

HUBERT SCHARDIN 273 

A Microsecond Still Camera 

HAROLD E. EDGERTON and KENNETH J. GERMESHAUSEN 286 

Benefits to Vision Through Stereoscopic Films . REUEL A. SHERMAN 295 

Visual Monitor for Magnetic Tape ROWLAND L. MILLER 309 

Westrex Film Editer . G. R. CRANE, FRED HAUSER and H. A. MANLEY 316 

A Nonintermittent Photomagnetic Sound Film Editor . W. R. HICKS 324 

Automatic Film Splicer A. V. JIROUCH 333 

September Part II 

Foreword Developments in Stereophony . . WILLIAM B. SNOW 353 
Stereophonic Recording and Reproducing System HARVEY FLETCHER 355 

Experiment in Stereophonic Sound LORIN D. GRIGNON 364 

Loudspeakers and Amplifiers for Use With Stereophonic Reproduction 

in the Theater JOHN K. HILLIARD 380 

Multiple-Track Magnetic Heads 

KURT SINGER and MICHAEL RETTINGER 390 

Stereophonic Recording and Reproducing Equipment 

J. G. FRAYNE and E. W. TEMPLIN 395 

New Theater Sound System for Multipurpose Use 

J. E. VOLKMANN, J. F. BYRD, and J. D. PHYFE 408 
Basic Requirements for Auditory Perspective . . HARVEY FLETCHER 415 

Physical Factors in Auditory Perspective 

J. C. STEINBERG and W. B. SNOW 420 

Loudspeakers and Microphones for Auditory Perspective 

E. C. WENTE and A. L. THURAS 431 

Contents: Journal of the SMPTE Vol. 61 iii 



October 

Increasing the Efficiency of Television Station Film Operation . . . 

R. A. ISBERG 447 
A Mathematical and Experimental Foundation for Stereoscopic 

Photography ARMIN J. HILL 461 

Optical Techniques for Fluid Flow NORMAN F. BARNES 487 

Conversion of 16mm Single-Head Continuous Printers for Simul- 
taneous Printing of Picture and Sound on Single-System Negative . 

VICTOR E. PATTERSON 512 
An Improved Carbon- Arc Light Source for Three-Dimensional and 

Wide-Screen Projection EDGAR GRETENER 516 

Performance of High-Intensity Carbons in the Blown Arc 

C. E. GREIDER 525 
Specifying and Measuring the Brightness of Motion- Picture Screens . 

F. J. KOLB, JR. 533 
November 

Basic Principles of Stereophonic Sound WILLIAM B. SNOW 567 

Psychometric Evaluation of the Sharpness of Photographic Repro- 
ductions ROBERT N. WOLFE and FRED C. EISEN 590 

Random Picture Spacing With Multiple Camera Installations . . . 

R. I. WILKINSON and H. G. ROMIG 605 

High-Speed Photography in the Chemical Industry 

W. O. S. JOHNSON 619 

Full-Frame 35mm Fastax Camera JOHN H. WADDELL 624 

Primary Color Filters With Interference Films 

H. H. SCHROEDER and A. F. TURNER 628 

A 35mm Stereo Cine Camera C. E. BEACHELL 634 

Projector for 16mm Optical and Magnetic Sound . JOHN A. RODGERS 642 

German Test Film 652 

December 

Improved Color Films for Color Motion-Picture Production .... 

W. T. HANSON, JR., and W. I. KISNER 667 

Objective Evaluation of Projection Screens 

ELLIS W. D'ARGY and GERHARD LESSMAN 702 
An Apparatus for Aperture-Response Testing of Large Schmidt-Type 

Projection Optical Systems 

D. J. PARKER, S. W. JOHNSON and L. T. SACHTLEBEN 721 
Compact High-Output Engine-Generator Set for Lighting Motion- 
Picture and Television Locations M. A. HANKINS and PETER MOLE 731 
Glow Lamps for High-Speed Camera Timing . . . H. M. FERREE 742 
Bibliography on High-Speed Photography 749 

iv Contents: Journal of the SMPTE Vol. 61 



Correction of Frequency-Response Variations 
Caused by Magnetic-Head Wear 

By KURT SINGER and MICHAEL RETTINGER 



Wear on a magnetic-recording head reduces the front-gap pole-face depth 
and thereby produces an increase of the gap reluctance. This in turn pro- 
duces a higher effective bias flux which has an erase action and thus tends to 
attenuate the high frequencies as they are being recorded on the recording 
medium. It is the purpose of the paper to present these performance varia- 
tions as a function of the lowered inductance associated with head wear and 
to show how, simply through a correction of bias current, proper performance 
can be restored. 



I 



T HAS been noticed in the past that 
wear on a magnetic-recording head 
results in a decrease of high-frequency 
response of the overall magnetic re- 
cording-reproducing system and also 
in a change of head sensitivity. The 
information and data contained in this 
article explain the reasons for the 
change in frequency characteristic and 
offer a simple expedient for correcting 
the losses and thereby extending the 
useful life of magnetic heads. 

While the benefits of a high-frequency 
bias current employed in magnetic 
recordings have been described in 
numerous publications, it is not fre- 
quently noted that the use of too much 
bias entails the loss of recorded high 
frequencies. This is due to an erase 



Presented on May 1, 1953, at the Society's 
Convention at Los Angeles by Kurt Singer 
and Michael Rettinger, Radio Corporation 
of America, RCA Victor Div., 1560 N. 
Vine St., Hollywood 28, Calif. 
(This paper was received April 22, 1953.) 



action produced by the bias flux at the 
front gap of the recording head. As 
the recording medium moves past the 
gap, it is subjected to a rapidly alternat- 
ing magnetic field, which tends to restore 
the medium to its neutral or virginal 
state, wherein the magnetic dipoles are 
oriented heterogeneously. This effect is 
more pronounced for the high frequencies 
than for the lows and appears to be 
associated with the recorded wave- 
length. 

Wear on a magnetic-recording head 
reduces the front-gap pole-face depth 
and thereby produces an increase of the 
gap reluctance. This in turn produces 
a higher effective bias flux which has, 
as noted above, an erase action and thus 
tends to attenuate the high frequencies 
as they are being recorded on the re- 
cording medium. It should be noted 
that this higher front-gap reluctance is 
due only to the decrease in front-gap 
pole-face depth and not to any widening 
of the gap, which with our type of 



July 1953 Journal of the SMPTE Vol. 61 

















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Fig. 1. Frequency 
characteristic at initial 
bias current head in- 
ductance 4.9 inh, 45 
fpm. 



FREQUENCY IN CYCLES PER SECOND 



RECORD HEA6 



RECORD-REPRODUCE HEAD 



MS: 



14 MA. 
16 MA. 



100 1000 

FREQUENCY IN CYCLES PER SECOND 



10000 20000 



Fig. 2. Frequency 
characteristic vs. initial 
and optimum bias cur- 
rent head inductance 
4.5 mh, 45 fpm. 



6 



RECORD-REPRODUCE HEAD 



REPRODUCE HEAD 



000 
FREQUENCY IN CYCLES PER SECOND 



IOOOO 2OOOO 



Fig. 3. Frequency 
characteristic vs. initial 
and optimum bias cur- 
rent head inductance 
4.2 mh, 45 fpm. 



July 1953 Journal of the SMPTE Vol. 61 



magnetic-head construction remains con- 
stant. 

To permit a ready evaluation of the 
test results, it is desirable to describe 
the method of testing. First, a fre- 
quency recording was made with an 
MI-10795-1 Head hereinafter called 
the test head. The film speed was 45 
fpm and the initial bias current 16 ma 
at 68 kc. The recording was then re- 
produced on a similar head and the 
properly equalized output from it was 
taken as an indication of the per- 
formance of the test head as a record 
head. Next, the recording was re- 
produced on the test head and the output 
from it was taken as an indication of 
the performance of the test head as a 
combination record-reproduce head. A 
frequency film which had been made 
previously was then reproduced on the 
test head and the output from it was 
considered an indication of the per- 
formance of the test head as a reproduce 
head. The three frequency character- 
istics thus obtained are shown in Fig. 1. 
The top, center and bottom curves 
show the initial test-head performance 
as a record, record-reproduce and re- 
produce head, respectively. 

The test head was then removed from 
the recorder, lapped until its inductance 
was lowered by 0.4 mh, that is, reduced 
from an initial 4.9 mh to 4.5 mh. The 
entire test was then repeated, thereby 
obtaining new performance data on part 
of the test head as a record, record- 
reproduce and as a reproduce head. 
It was noticed that the change in fre- 
quency response (loss of highs) resulting 
from the lowered inductance was greater 
when the head was used as a record head 
than when it was used as a reproduce 
head. To restore the frequency re- 
sponse of the record head to normal, 
the bias current had to be reduced to 
14 ma. The frequency characteristics 
obtained from the test head with its 
inductance reduced to 4.5 mh are 
shown in Fig. 2. The upper and center 
curves show head performance as a 



record and record-reproduce head with 
the initial bias of 16 ma, and the reduced 
bias of 14 ma (dashed line). The test 
head was then removed again from its 
mount, lapped so that its inductance was 
lowered again by a certain amount, in 
this case from 4.5 to 4.2 mh, and the 
tests were repeated. The frequency 
characteristics obtained from this series 
of tests are shown in Fig. 3. Again it 
should be noted that the reduction of 
bias current to 12 ma for this head 
inductance of 4.2 mh restored head 
performance to normal. Figures 4, 
5 and 6 depict the head performance 
for inductances of 3.85, 3.5 and 3.1 mh. 
These curves also show the change in 
bias current required to regain proper 
frequency characteristics. 

Figure 7 shows the gradual loss in 
high frequencies as the recording-head 
inductance drops from 4.9 to 3.1 mh 
at a constant bias current of 16 ma. 

When the region of maximum sensi- 
tivity bias of the record head over the 
range of inductances from 4.9 to 3.1 
mh was investigated, it was noticed 
that the initial bias current of 16 ma 
and the reduced optimal bias currents 
in all cases represented bias currents 
corresponding to a value either equal to 
or slightly lower than maximum sensi- 
tivity bias. However, this statement 
should not be construed to mean that 
it is only necessary to adjust the bias 
current to maximum sensitivity bias to 
recover the lost high frequencies. This 
procedure would only result in an 
approximately normal performance. In 
order to compensate for head wear 
accurately, it is necessary to reduce the 
bias current experimentally to a value 
which will produce the initial frequency 
characteristic. 

During these tests it was also noticed 
that a sensitivity change of the test head 
took place. The sensitivity variations 
are shown in Fig. 8. Zero sensitivity 
of the test head as a record head corre- 
sponds to the sensitivity of the head with 
its full inductance of 4.9 mh operating 



Singer and Rettinger: Correcting Frequency Response 



RECORD' HEAD' 



RECORD-REPRODUCE HEAD 



100 1000 

FREQUENCY IN CYCLES PER SECOND 



10000 20000 



Fig. 4. Frequency 
characteristic vs. initial 
and optimum bias cur- 
rent head inductance 
3.85 mh, 45 fpm. 



-5 

-10 
20 



RECORD-REPRODUCE HEAD 



FREQUENCY IN CYCLES PER SECOND 



Fig. 5. Frequency 
characteristic vs. initial 
and optimum bias cur- 
rent head inductance 
3.5 mh, 45 fpm. 



RECORD HEAD 




100 1000 

FREQUENCY IN CYCLES PER SECOND 



10000 20000 



Fig. 6. Frequency 
characteristic vs. initial 
and optimum bias cur- 
rent head inductance 
3.1 mh, 45 fpm. 



July 1953 Journal of the SMPTE Vol. 61 



Fig. 7. Frequency 
response vs. induct- 
ance of recording head 
measured at constant 
bias of 16 ma. 45 fpm. 




1000 
FREQUENCY IN CYCLES PER SECOND 




Fig. 8. Head in- * 
ductance vs. sensitivity 
change, 45 fpm, 400 
cycles. 



HEAD INDUCTANCE MH 



Fig. 9. Head in- 
ductance vs. optimum 
bias current vs. 100% 
modulation level, 400 
cycles, 45 fpm. 




Singer and Rettinger: Correcting Frequency Response 





































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at a bias current of 16 ma. It should 
be noted that as the head inductance is 
decreased, and the head sensitivity 
increased, it is necessary in order to 
obtain 100% modulation (approximately 
2.5% distortion at 400 cycles), that the 
signal input to the head (signal current) 
be reduced by the amount shown on 
this curve. In exploring the per- 
formance of the test head as a reproduce 
head, zero sensitivity was assumed as 
the sensitivity of the head with an 
inductance of 4.9 mh. As the head 
inductance was lowered, the output from 
the head increased by the amount shown 
on this curve. 

Figure 9 shows the change in the 100% 
modulation level that was noted as the 
head inductance was decreased and the 
bias current readjusted for satisfactory 
high-frequency performance. 

Figure 10 has been included to show 
approximate values of optimum bias 
currents which can be used in an initial 
attempt of correcting for high-frequency 
loss by the record head when the head 
inductance has been reduced due to 
head wear. It must be understood 
that this curve can only be offered as an 
approximation toward the desired opti- 
mal bias current. Minor deviations 
from it may exist in individual cases. 

All the tests described above have 
been made at a film speed of 45 fpm. 



Fig. 10. Head in- 
ductance vs. optimum 
bias current, 45 fpm. 



The attenuation of recorded high fre- 
quencies due to magnetic-head wear 
at other film speeds will have the same 
trend, although it does not necessarily 
follow that the same patterns, obtained 
with a 45-fpm film speed, will result. 
However, practice has shown that in 
all cases it has been possible to regain 
lost high frequencies through a reduction 
of bias current. 

We would like to inject a note of 
caution, namely, that each change in 
bias current necessitates the re-establish- 
ment of the 100% modulation recording 
level to avoid overloads and resultant 
increase in distortion. 

Discussion 

Anon: I would like to know if you're 
getting any variation in the signal-to-noise 
ratio out of your tape with this output 
variation, a decrease of high-frequency bias 
and concurrently of modulation level. 

Mr. Singer: No, we have not noticed any 
deterioration of signal-to-noise ratio. The 
signal-to-noise ratio essentially stays the 
same, as with the initial bias and the 
initial modulation level. 

Anon: Because, of course, the maximum 
level that you get from your tape must de- 
crease definitely. Then, suppose you are 
recording 100% as established by 2.5% 
distortion. You recorded with a normal 
head and normal conditions 16 ma and 
whatever db level you're using. Then you 
record a second tape at a lower general 



July 1953 Journal of the SMPTE Vol. 61 



level with another head. If you produce 
these two tapes, both recorded at 100%, 
you must evidently get a lower level out of 
the second tape than you got from the 
first tape. 

Mr. Singer: No, we do not obtain ,m\ 
lower level from the second tape, because 
the magnetization that is inherent in the 
film will be the same. If they're going to 
work at the same bias sensitivity, they will 
also have the same voice sensitivity. As 
the head wears down and the gap reluc- 
tance increases, its flux fringing which in- 
creases is applicable to the bias flux as well 
as to the modulation flux. So, essentially, 
we get the same output. I don't think we 
noticed more than maybe a db output 
variation over the entire range of head 
inductances and bias correction. 

George Lewin (Signal Corps Pictorial Center) : 
Can you give us a rough idea of how many 
feet of film you run through before you 
reach the extreme values of head wear that 
you indicate here? 

Mr. Singer: Perhaps Mr. Rettinger is in 
a better position to answer this question? 

Mr. Rettinger: The head was lapped down 
by hand on a 600 grit silica carbide paper. 

Mr. Lewin: Yes, I understand that. But 
you must have some idea as to how much 
equivalent footage is represented. 

Mr. Rettinger: In general, you mean? 

Mr. Lewin: Yes, that's right. 

Mr. Rettinger: It depends on a number of 
factors such as film speed, type of tape, film 
tension, etc. On a triple-track head, in 
one of the studios for instance, we were 
able to pass over 3 million feet of film be- 
fore the head inductances had lowered to 
3mh. 

Mr. Lewin: Which is the extreme amount 
that you showed here. Three million feet 
of film, you say, is roughly the equivalent 
of the maximum amount of wear that you 
showed? 

Mr. Rettinger: That's right. 



Anon: What sort of life should we expect, 
roughly, from the reproducing heads in 
terms of feet of film that run over them 
and also near the end of that life, what is 
to he expected with regard to the output 
level .uid the eh.uiLM- in li<<|iiene\ response, 

if any? 

Mr. Rettinger: As I just said, one may 
expect at least 3 million feet of film to 
pass over the head before its inductance 
has dropped to 3 mh. That is, under the 
condition that we call the tight-loop system. 
Where there's less film tension on a head, 
the life of the head may be extended. 
How long? I don't have that information 
available. With regard to sensitivity varia- 
tion, I think that was indicated on the 
slides. There would be approximately a 
3-db gain in head sensitivity when the 
inductance has been lowered from 5 to 
3 mh. 

Anon: Would Mr. Rettinger continue and 
indicate the change in the frequency re- 
sponse near the end of reproducer head 
life? 

Mr. Rettinger: That was shown on the 
curve. There's very little change in the 
frequency response of the reproduce head 
down to, let us say, 3 mh. After that 
when the gap begins to open up, naturally 
there will be a rapid falling off of high- 
frequency response. 

Anon: Is what you said applicable in 
general to most any make of reproduce 
head that we might find in theaters in the 
near future, as far as we know? 

Mr. Rettinger: Not necessarily. It de- 
pends on the way the head is constructed. 
If the front gap is built so that it remains 
of constant length as the head wears down, 
I would expect very little change in fre- 
quency response. But if the head is built 
so that the front gap will lengthen as the 
head is worn down, then, naturally, there 
will be a loss of high frequency. Our 
heads are built so that the gap length 
remains constant. 



Singer and Rettinger: Correcting Frequency Response 



16mm Motion-Picture Theater Installations 
Aboard Naval Vessels 

By PHILIP M. COWETT 



The Navy's shipboard motion-picture installations, involving special location 
problems calling for equipment of great flexibility, and acoustic problems 
complicated by high noise levels, are briefly described. 



w, 



E HAVE presented to this Society 
at various times the Navy story re- 
garding the problems incurred in the 
procurement of film of adequate quality 
to meet the needs aboard ship. We 
have never, however, described before 
this Society the theater installations 
utilizing 16mm equipment aboard Navy 
vessels located throughout the world. 
These installations generally break down 
into categories of ships such as de- 
stroyers, aircraft carriers, battleships 
each with its own specific problem. The 
purpose of this paper is to describe some 
of these installations and set forth the 
Navy's program at this time with regard 
to 16mm film and its professional use 
as a serious entertainment medium. 

Following the last world war, a survey 
was made of the various overseas shore- 
based activities and ships to determine 
whether they desired to continue with 
the use of 35mm film and equipment 



Presented on April 22, 1952, at the Society's 

Convention at Chicago by Philip M. 

Cowett, Dept. of the Navy, Bureau of 

Ships, Washington 25, D.C. 

(This paper was first received March 26, 

1952, and in revised form on June 26, 

1953.) 



or convert to the equivalent in 16mm 
with its obvious advantages with regard 
to transportation, handling, lack of 
fire hazard and so forth. This resulted 
in the report from the various polled 
activities that 16mm would be very 
desirable from the standpoint of naval 
use if equipment could be procured that 
would match the 35mm equipment 
characteristics. 

Obtaining adequate equipment be- 
came a separate project which resulted 
in the development of two projectors 
meeting identical performance requisites. 
As to the equipments themselves, they 
have been described in the paper pre- 
sented before the Society by Orr and 
Cowett in 195 1. 1 Very little more need 
be added as to their performance. 

As may be realized, a naval vessel is 
designed and constructed for one pur- 
pose and that purpose, unfortunately 
for the motion-picture viewer, is not the 
showing of motion pictures. Since 
nothing is allowed to take place aboard 
ship which will interfere with the prime 
mission of the ship, our activities must 
accommodate themselves in any manner 
possible. One thing, however, becomes 
readily apparent, and that is the absence 



July 1953 Journal of the SMPTE Vol. 61 



of acoustic treatment in any part of 1 1 it- 
ship. Therefore, there is really no best 
location for the evening show. 

The first, or simplest type of installa- 
tion, is that to be found aboard a de- 
stroyer or lesser craft. In this case 
the particular vessel is assigned a 
standard portable equipment, com- 
prising a projector, 20-w amplifier, 
and 25-w loudspeaker. Individual ships 
sometimes manufacture portable bases 
for themselves, but none are provided 
as an allowance item. Figure 1 shows 
a single equipment (except for the loud- 
speaker) on board an LST. 

Since the distances of throw are varied 
and limited, and the availability of 
permanent locations for the projection 
of film is nonexistent, it is essential 
that the equipment be easily portable. 
In good weather the shows are generally 
projected topside under the stars where 
high ambient noises are the rule. The 
projector, mounted on a steel stand, 
which is generally lashed to the deck, 
is set up in the most suitable location for 
the particular vessel, between 50 and 
175 ft from the screen which measures 
approximately 9 ft 6 in. in width. 
With this vibrating platform as a 
projection booth preparations for the 
evening show go on. Vibration is due 
to the fact that on many types of vessels 
one of the two propeller shafts of the 
ship passes almost directly beneath the 
point where the projector is set up. 
Interconnection between the various 
units is established and the show is 
ready to start. 

Of course the portable direct radiator 
type loudspeaker is mounted as high as 
possible close to the screen in order 
that adequate sound coverage may be 
obtained. There is not much in the 
way of height around the screen except 
the screen frame itself, which may or 
may not be able to support extra weight, 
since the screen acts as a sail and addi- 
tional weight could cause it to buckle 
completely. When the ship is traveling 
by itself, with no particular time schedule 



for arriving at any urn- IMIMI ul.n pint. 
or where a ship can make up lost time. 
the Commanding Officer will normally 
reduce the speed of the ship to iili n 
knots or less or even change course 
for the duration of the show. This 
permits a properly lashed down Kreen 
to remain in place without too much 
flapping. 




Fig. 1. Portable projector and amplifier. 

It has been stated that two projection 
equipments had been developed one 
a 20-w unit and the other a 5-w system. 

The 5-w unit is aboard ship for train- 
ing purposes, since a vessel of destroyer 
size is not large enough to warrant two 
projection equipments for entertain- 



Cowett: Shipboard 16mm Installations 



ment purposes alone. There is, how- 
ever, a definite advantage in the use of 
even one 16mm equipment as compared 
with the 35mm, since we have to change 
reels only once every 45 or 50 min, 
whereas with 35mm, reel changing is 
much more frequent. 

The 5-w equipment is designed with 
changeover facilities as is the 20-w 
equipment previously mentioned. Since 
both the 5-w and 20-w equipments have 
identical characteristics 2 and identical 
inputs and outputs including plugs and 
receptacles, the two can be intercon- 
nected in such a manner that a dual 
show may be given, without stopping 
the projectors for changing reels, and 
thereby accomplishing instantaneous 
changeover in the same manner as do 
professional 35mm equipments. In this 
instance the outputs of both projectors 
feed into the 20-w amplifier, and that 
20-w amplifier provides exciter supply 
for both the 5-w and 20-w projection 
equipments, the 5-w amplifier being 
isolated. 

Aboard larger vessels, such as a 
battleship or cruiser, a booth installation 
is involved. As in the previous instance, 
the high ambient noise still governs, and 
the same obstacles exist with regard to 
securing satisfactory sound distribution 
topside. Cross winds, engine-room 
blower noises, noise of the ship under- 
way all act to hinder the intelligi- 
bility of sound to a maximum extent. 
Of course, the effects of the moon on 
the picture are also noticeable. 

Figure 2 shows a typical shipboard 
booth installation. The booth is 
mounted generally just abaft the main 
mast structure. The screen is located 
topside at the fantail, or stern of the 
vessel, and in some cases the distance 
between the only possible location of the 
projection booth and the only possible 
location of the screen is in excess of 200 
ft. This installation consists of the 
following components: two projectors 
operating as a dual system mounted on 
specially designed projector stands, which 



include tilt plates, as in 35mm equip- 
ments, and mounting places below the 
projectors for the amplifiers. In addi- 
tion a monitor loudspeaker, record 
player, film stowage space, rewind 
facilities, etc., are also available. 

Changeover facilities are provided as 
in the installation previously described. 
The two standard Navy 20-w amplifiers 
are bridged at the front ends through 
telephone-type jacks. This allows a 
supply of an effective 40 w of power to 
the loudspeaker system located below 
on the main deck. Figure 3 shows the 
circuits involved in a cruiser installation. 

Since the theater areas in ships of 
this type must be relatively long, as 
compared to their widths, and because 
of the various cross winds and miscel- 
laneous noises encountered, it was 
necessary that a loudspeaker installation 
be designed especially for this type of 
ship. There is permanent ship's wiring 
between the projection booth and the 
loudspeakers themselves. The loud- 
speaker installation consists of two 
horns, or trumpet-type loudspeakers, 
mounted on the topmost corner sections 
of the husky screen frame. These horns 
are tilted to cover approximately the 
rear portion of the audience. They are 
parallel connected to one of the 20-w 
amplifiers in the booth which inde- 
pendently controls the volume and tone 
control characteristics of the sound 
from these particular loudspeakers. 
Portable-type direct radiator loud- 
speakers, previously mentioned, are 
mounted about halfway up on either 
side of the screen frame. These are 
tilted in the same manner as the horns; 
however, they cover only the front 
portion of the audience. They too are 
separately controlled by their own 
individual amplifier. The loudspeaker 
installation can be seen in Fig. 4. With 
this type of system the Navy endeavors 
to provide good quality sound, or as 
good sound as we can achieve under the 
particular topside conditions. 

When the show is over the four loud- 



10 



July 1953 Journal of the SMPTE Vol. 61 




Fig. 2. 16mm shipboard booth installation (Official Photograph, U.S. Navy). 



speakers and the screen with frame are 
completely dismantled and stowed away 
in assigned spaces until the following 
evening. During bad weather, pro- 
jectors used generally for training pur- 
poses, the 5-w unit previously mentioned, 
or even the 20-w booth equipment can 
be taken into the wardroom, the crew's 
mess, or any other interior space and a 
reasonably good show given. 

Projection below deck involves prob- 
lems of steel bulkheads, decks, over- 
heads, and so forth, which may result 
in some reverberation. The size of the 
audience is depended upon to deaden 
the sound. During inside shows dual 
operation of the projection equipments 
is not usually feasible in view of the 
fact that spaces are too small to hold 
the entire audience at one time. There- 
fore, shows are held simultaneously in 
several different compartments. Each 
show cannot start at the same time since 



reels must be passed from one projection 
area to the other. 

A third type of installation would be 
that on an aircraft carrier, where 
extremely bad acoustical conditions 
result in a completely different approach 
to sound problems. The show, first of 
all, is presented in one of the hangar 
areas, normally used for the stowage 
and repair of aircraft. In some ships 
such an area is approximately 100 ft 
in width, 180 ft in length and 18 ft in 
height. The booth is mounted just 
below the overhead at one end of the 
area and projection is toward one of 
the hangar bay doors on which an 18-ft 
lace and grommet screen is mounted. 
A typical motion-picture hangar is 
shown in Fig. 5. 

Projection distances of approximately 
170 ft are average in our largest carriers. 
The projection booth is about the same 
as that on a battleship or cruiser about 



Cowett: Shipboard 16mm Installations 



11 







(D 




TO 1C SWITCMBOAHO 



Fig. 3. Cruiser installation electrical wiring layout. 



12 



July 1953 Journal of the SMPTE Vol. 61 




List of Material Quantities for One Ship 



Item 

No. Name 

1 Projector 

2 Amplifier 

3 Loudspeaker, monitor 

4 Loudspeaker, horn type 

5 Loudspeaker 

6 Sound reproducer 

7 Projector mounting base 

8 Distribution box 

9 Branch box 

10 Receptacle, double, W.T. 

1 1 Jack box, W.T., telephone 

12 Plug, receptacle, SBM 

13 Plug, telephone 

14 Plug, three connection 





Item 


Qty. 


No. 


2 


15 


2 




1 


16 


2 


17 
18 


2 


19 


1 


20 


2 


21 


1 




2 


22 


1 




1 


23 


2 


24 


2 


25 


5 





Name 

Blkhd. mtg. bracket for sound re- 
prod. 

Studs for mtg. item nos. 3 and 15 
Power cable assembly 
Changeover cable assembly 
Photoelect. cell cable assembly 
Amplifier bridging cable assembly 
TTHFWA 1 J cable, lengths as re- 
quired 

TTHFWA 3 cable, length as re- 
quired 
Cable, shielded, 2 cond., length as 

required 

Cable, DCOP-2, length 75 ft 
Mtg. bracket for type IC/QDM 
loudspeaker 



Cowett: Shipboard 16mm Installations 



13 




PROVIDE RECESS IN BRACKET TO RECEIVE 
FEET ON LOUDSPEAKER TO PREVENT SLIPPING 

FOR THROUGH BOLTS AND CHANNEL OR 
ANGLE IRON SCREEN FRAME 



FOR U BOLTS AND PIPE SCREEN FRAME 
TO SUIT PIPE SCREEN FRAME 



Fig. 4. Loudspeaker in- 
stallation. 




LOCATE NEAR 



8 ft wide by 10 ft deep by 7 ft high. 
It contains a rewind table, a little stowage 
space, record player, and so forth. 

The loudspeaker system is, however, 
completely different from any of the 
other systems used. Instead of the 
portable loudspeakers, a number of 
12-in. loudspeakers in one-cubic-foot 
enclosures are mounted to the overhead 
and spaced approximately on 9-ft 
centers. Carriers of the Midway class 
have approximately 36 loudspeakers 
mounted to the overhead (Fig. 6). 
They are each tilted 20 toward the 
audience in order to minimize the re- 
verberation which might be caused by 



the sound bouncing on the steel deck 
between rows of seats. As can be seen 
by the loudspeaker arrangement, space 
is allowed for a passageway in the 
middle of the audience. All loud- 
speakers are terminated in a switch 
control panel in the booth so that the 
quantity of loudspeakers on at any one 
time may be adjusted to the size of the 
audience. Advantage is taken of the 
sound deadening capacity of the audience 
and more loudspeakers are therefore 
connected as the crowd grows. This 
is a real advantage and allows maximum 
intelligibility from sound to be obtained. 
The loudspeaker system is powered by a 



14 



July 1953 Journal of the SMPTE Vol. 61 




Fig. 5. Motion-picture hangar area, U.S.S. Oriskany (CVA34) 

(Official Photograph, U.S. Navy). 




Fig. 6. Overhead loudspeaker layout for U.S.S. Midway class aircraft 



carrier. 



constant voltage of approximately 1 00 v. 
Each loudspeaker enclosure contains a 
transformer which permits the sound 
output from any one particular loud- 
speaker to be adjusted depending upon 
the noise level of the area in which the 



loudspeaker is located. This, therefore, 
permits an even sound distribution to 
reach the entire audience regardless of 
the noise level surrounding any one 
person. It is obvious, however, that 
high ambient noises of 80 to 90 db, and 



Cowett: Shipboard 16mm Installations 



15 



Fig. 7. Electrical wiring for 16mm 
projection equipment installation in 
all aircraft carriers. 








16 



July 1953 Journal of the SMPTE Vol. 61 



List of Material 



Name 

l'l(l|C( III) 

Amplifier 

Loudspeaker 

Sound reproducer 

Projector mounting base 

Distribution box 

Telephone jack switch box 

Telephone jack switch box 

Switch, D.P.S.T. 

Plug, telephone 

Plug, three connection 




12 
13 

14 

15 
16 

17 

IK 
1') 

20 
21 



MNM 

Blklul. intg. bracket for sound reprod. 
Studs for mtg. item nos. 3 and 12 
Power cable assembly 
Changeover cable assembly 
Photoelect. cell cable assembly 
Amplifier bridging cable assembly 
TTHFA 1 J cable, lengths as required 
Cable, shielded, 2 cond., length as re- 
quired 

TTHFA 10 cable, lengths as required 
Connection box 



Cowett: Shipboard 16mm Installations 



17 



reflections and reverberations in the 
projection area provide serious obstacles 
to the hearing of highly intelligible 
sound. 

This situation, however, is not unlike 
that in many industrial areas where 
loudspeakers are used for public an- 
nouncing involving coverage over a 
wide area of enclosed space. Experi- 
ments are continually being made to 
solve the acoustic problems involved. 
Various types of loudspeakers and loud- 
speaker systems are being tested in order 
to procure a more satisfactory final result. 

A perfect theater can never result 
from the efforts made in this direction 
since the spaces allocated for motion 
pictures on ships have to fill their primary 
combat functions first, and can be 
adapted only secondarily for motion 
pictures. This, then, means that sound 
deadening material must be held to a 
minimum. Inflammable materials are 
absolutely out, no matter how good 
their acoustical properties may be. 

Only one 20-w amplifier is used to 
cover the hangar area and to feed the 
booth monitor loudspeaker. From Fig. 7 
it will be seen that both projectors can 
be fed to one or the other of the ampli- 
fiers. Two projectors feeding into one 



amplifier can be instantaneously shifted 
to the input of the stand-by amplifier 
in the event of the failure of the working 
amplifier. Should other peculiar condi- 
tions arise, each projector may feed 
into its own amplifier with both ampli- 
fiers individually feeding into the same 
overhead loudspeaker system. The 
switches which accomplish this change 
are identified by the numeral 9 in the 
center of the figure. In this manner 
we have attempted to provide a system 
of maximum flexibility because the con- 
ditions of use are subject to change 
without notice, depending almost en- 
tirely upon the number of persons 
attending the show; that is to say, of 
the amount of acoustic or sound ab- 
sorption material present in the hangar 
bay area. This, of course, would be in 
addition to the change of film itself. 

References 

1. Lowell O. Orr and Philip M. Cowett 
"Desirable characteristics of 16mm 
entertainment film for naval use," 
Jour. SMPTE, 58: 245-258, Mar. 1952. 

2. "Tentative recommendations for 16mm 
review rooms and reproducing equip- 
ment," Jour. SMPTE, 56: 116-122, 
Jan. 1951. 



July 1953 Journal of the SMPTE Vol. 61 



A First-Order Theory of Diffuse 
Reflecting and Transmitting Surfaces 



By ARMIN J. HILL 



Intensity of light emitted or reflected from a surface in accordance with Lam- 
bert's law varies in proportion to the cosine of the angle between the direction 
of the light beam and the normal to the surface. With many surfaces which 
do not follow this law, it is possible to approximate the variation of intensity 
with some power of the cosine. When such an approximation can be made, 
relatively simple relationships can be obtained for luminance (brightness), 
emittance and related factors. Use of this approach may take some of the 
mystery out of such problems as the determination of screen brightness and 
a study of transmission characteristics of process screens. 



.LJAMBERT'S LAW, which states that 
the intensity of light emitted from a 
perfectly diffusing radiator is propor- 
tional to the cosine of the angle between 
the normal to the emitting surface and 
the direction in which the intensity is 
measured, provides a simple mathe- 
matical basis for treating luminous 
surfaces which radiate according to this 
law. Unfortunately, few surfaces are 
perfect diffusers and serious errors will 
result if the simple equations derived 
from Lambert's law are applied to them. 
Many of the reflecting and transmitting 
screens used in the motion-picture and 
television industries are, in fact, quite 



Presented on October 9, 1952, at the 
Society's Convention at Washington, D.C., 
by Armin J. Hill, Motion Picture Research 
Council, 1421 North Western Ave., 
Hollywood 27, Calif. 

(This paper was first received on No- 
vember 3, 1952, and in revised form on 
May 12, 1953.) 



highly directional, though not enough 
so that they can be treated according 
to the laws governing specular reflection 
or direct transmission. 

Considerable literature is available 
on the theory of radiation transfer and 
on the processes by which light is 
diffused and scattered as it traverses 
various media. Most of this has ap- 
proached the problem from too funda- 
mental a viewpoint, however, to provide 
workable equations by means of which 
"partial diffusion" might be treated. 
This paper suggests an approach which 
is almost entirely empirical, based upon 
experimental tests on transmitting and 
reflecting screens, disregarding com- 
pletely the processes by which this 
transmission or reflection takes place. 
These processes are therefore treated 
exactly as they are in applications of 
Lambert's law. The slight modification 
of the equations does not prevent, in 
most cases, an extension of the ideas 



July 1953 Journal of the SMPTE Vol, 61 



I 1 ) 



based on this useful law to include 
directional screens and to treat these 
screens in the simple manner otherwise 
only safely applicable to perfect diffusers. 

In analyzing the characteristics of 
translucent screens used for back- 
ground process projection, it was noticed 
that the fall-off of intensity with increas- 
ing angle from the normal would be 
closely approximated, not by a cosine 
curve as for a perfect diffuser, but by 
using some power of the cosine of the 
angle. To show how closely this ap- 
proximation holds, Figs, la-d show ex- 
perimental curves obtained by means 
of a goniophotometer on experimental 
screens analyzed by Dr. Herbert Meyer 
of the Motion Picture Research Council. 
(Data were taken according to require- 
ments of A.S.T.M. Designation D636- 
43.) The dashed curves in each set 
represent suitably selected cosine power 
curves, with the selected power used as 
a "shape factor" and symbolized by 
the letter s. It is immediately apparent 
that except for very low intensities, the 
cosine curve matches the experimental 
curve within a few percent in fact 
in most cases within the instrumental 
error of the goniophotometer. Since 
most of the errors at very low intensities 
tend to make the readings too high, 
actual fit may be even better than that 
shown by the diagrams. 

This comparison was then tried on 
data for typical reflecting types of 
surfaces with results as shown in Figs. 
2a-d. 1 It will be seen that within 
angles of interest for most photographic 
work, the approximations again are 
good within a few percent. Care must 
be used, of course, in applying these 



1 Sources for these data were: (a) for sand- 
blasted mirror, James R. Cameron, 
Motion Picture Projection, Cameron Pub- 
lishing Co., Coral Gables, Fla., 4th ed., 
p. 199; (b) for others, Ellis W. D'Arcy 
and Gerhart Lessman (De Vry Corp.), 
"Objective evaluation of projection 
screens," presented on April 22, 1952, 
at the Society's Convention at Chicago. 



in such cases as the beaded screen where 
a considerable portion of the total flux 
is emitted at large angles, for in such 
cases relations involving this total flux 
will be seriously in error. However, 
the particularly important relations 
between intensity, luminance and il- 
luminance will hold when only small 
angles are involved. 

In the following formulae, notation 
follows that employed by Sears. 2 

Definitions: 

F, luminous flux; 

I, luminous intensity or flux per unit 

solid angle; 

B, luminance (brightness); 
E, illuminance or flux per unit area 

received at a surface; and 
L, luminous emittance or total flux 

emitted per unit area. 

Defining equations: 
jpi 

I = , where co is solid angle with 
dco 

vertex at source; 

dF 10 cos 6 

= - , where 6 is angle 



B = 



dA r" 

with normal to surface; 

AI0 

and 



AAcos0 

AF 

L = -, F is total emitted flux. 

AA 

The following equations compare 
intensity and brightness for a surface 
which follows Lambert's law, with one 
which is directional but for which the 
intensity falls off in proportion to some 
power s of the cosine of the angle with 
the normal to the surface. 

Lambert Surface Directional Diffuser 

10 = I cos 10 = I cos 8 

B0 = B L B0 



Here B L represents the brightness of the 
Lambert surface, and B D the normal 
brightness of the directional surface. 



2 E. W. Sears, Principles of Physics, Vol. 3 
Optics, Addison- Wesley, Cambridge, Mass., 
1948, 3d ed., chap. 13. 



20 



Jqly 1953 Journal of the SMPTE Vol. 61 



.SS>- PERCENT 

h -j OB <o o 
3 O O O O 


\ 




TRANSLUCENT 




\ 


SCREEN-A 




\ 














\ 


\ 










1ECBRIGHTNE 

u> c 
) O < 






V 


,CREEN 











\ 










Z 

Z 








V 








RELATIVE LUK, 

- r\> c, 
O o o c 








\ 


^S-2 


9.5 












N 


\ 












\ 


\ 

X. 


\ 



10 20 30 

ANGLE WITH NORMAL - DEGREES 



IOO 


\ 




TRANSLUCENT . 


INANCE (BRIGHTNESS) - PERCEN T 

j J> Cn 0> -N| 09 1 
3 O O O O O C 


N 


\ 
\\ 




SCREEN -C 






\ 














\ 
















\ 














\ 


^-sc 


REEN 










\ 


\ 








UJ 20 

H 
< 






















V 


k 


-31.0 

k. 




UJ 


o 










E 


- 



90 
60 


\ 




TRANSLUCENT 
SCREEN -B 




\ 


1 




\ 












C 'J 
ui 60 




\ 


V 










S so 






\ 










8 

U 40 






\ 










u W 

i 30 








V s0 


REEN 






UJ 2O 








\ 


^ S- 


26.0 




g 

< , 










x\ 


V 




_| IW) 

i 














r^ 


\ 



10 20 30 

ANGLE WITH NORMAL -DEGREES 



10 20 30 

ANGLE WITH NORMAL - DEGREES 



90 
- 80 

UJ 

U 
Pi 70 


\ 




TRANSLUCENT 


\ 




SCREEN -D 




\ 












E 

i 




\ 












(BRIGHTNES 
, g S 




\ 














\ 












LUMINANCE 

u W i 
3 c 






V-SCREEN 












\ 










UJ 

> 

10 






\> 


x'; 


57.0 






_l 
UJ 


n 








'^ 







10 20 30 

ANGLE WITH NORMAL -DEGREES 



Fig. 1. Approximations of luminance fall-off for experimental translucent screens. 

Solid curves show experimental data, dashed curves show ratios of B0/B 

obtained from the equation B0 = B,, cos 8 ty. 



Hill: Theory of Reflecting and Transmitting Surfaces 



'21 



9 


"X 


\ 




1 1 1 
PLASTIC 


BO 
70 

60 
50 
4-0 
30 




\ 




DIFFUSER 






V 


DIFFl 


JSER 










\s 


\ 














x \ 

\ 

\ 


^ 












\ 

x 


^S"A 


.2 
































\0 






























20 40 60 

ANGLE WITH NORMAL - DEGREES 





A 




A 


1 
LUMINIZED 
CLOTH 






\ 












\ 












60 




\ 












50 




\ 












40 
3 




\\ 
\ 


Y<sc 


REEN 












\\ 










^n 






\\ 


xS-l 


5.0 






in 






\ 
\ 


\ 


s 






n 








\ 
\ 
s 


"*C 


^^ 






IUU 

90 

H 


\ 




BEADED GLASS 


\ 


\ 


SCREEN 


E LUMINANCE (BR IGHTNESS) - PERCE 

) < |k Ut Q oj < 

> O O O O C 




\ 














\ 
















V 














V 


EADE 


3 SCR 


EEN 








\ \ 

\ 


V. 


^" 


^ 








i 


V s * 


10.5 






RELATIV 
a $ 








\ 
\ 
















\ 







20 40 60 

ANGLE WITH NORM AL - DEGREES 



20 40 60 

ANGLE WITH NORMAL -DEGREES 



SAND-BLASTED 
MIRROR 




20 40 60 

ANGLE WITH NORMAL -DEGREES 



Fig. 2. Approximations of luminance fall-off for typical reflecting screens. 

Use of solid and dashed lines is the same as for Fig. 1; parts 

a-d, in the usual order 



22 



July 1953 Journal of the SMPTE Vol. 61 



The illuminance or flux received per 
unit area at a point not on the screen 
illuminated by a circular area of the 
screen whose center is at the foot of the 
perpendicular from the point and whose 
radius subtends an angle a at the point 
is found by integration to be : 

Lambert Surface 



E = 



L sin 2 a 



Directional Diffuser 
E D = - B D (1 -cos- +1 a) 

and the luminous emittance or total flux 
emitted by a unit area of the screen 
surface is: 



Lambert Surface 
L = *-B L 



Directional Diffuser 

L. -^ Bt 



If we neglect any differences which 
may exist in absorption or other screen 
losses, we can compare maximum normal 
brightness by assuming that the total 
luminous emittances are equal, in which 
case we see that 



B D = 



s + 1 



This shows clearly why the "brightness" 
of a directional screen in footlamberts 
may often be several times the intensity 
of the incident radiation in foot-candles. 
The "shape factor," s, provides a 
convenient index to the diffusing charac- 
teristics of the screen. For a perfect 
diffuser, it is of course, unity, while for 
a nondiffuser (free transmission or 



specular reflection) it becomes infinite. 
As shown by the curves in Figs. 1 and 2 
it usually takes on values between 1 and 
50. 

These equations show why meters 
which actually read illuminance instead 
of luminance, do not give correct 
luminance readings for directional 
screens. For example, a meter such 
as the G.E. screen-brightness meter, 
having an admittance half-angle of 15 
will read about 8.5% low, while for a 
screen having s = 10 this will drop to 
20.5% below what it should read. 

These equations have been found to 
be useful in predicting size and relative 
intensities of "hot spots" from data 
obtained from relatively small screen 
samples, in correcting transmission data 
taken by the various methods in current 
use, and in suggesting designs for suitable 
instruments for use in measuring various 
screen characteristics. They should 
also prove useful in the analysis of screen 
brightness data. Dr. Meyer 3 has found 
that some types of translucent screens ap- 
parently have s-factors which are 
dependent upon wavelength. There- 
fore, these equations may prove helpful 
in specifying tolerances for screens 
suitable for work with color photography. 
In any case, they extend the simplicity 
of mathematical treatment now ap- 
plicable to Lambert diffusers to many 
important types of directional diffusing 
surfaces, and as such should be of interest 
and use in the motion-picture and 
television industries. 

3 Private communication from Herbert 
Meyer of the Motion Picture Research 
Council. 



Hill: Theory of Reflecting and Transmitting Surfaces 



23 



Photography of Motion 



By JOHN H. WADDELL 



The use of photography for determining velocities, accelerations and degrees 
of movement in high-speed phenomena as well as in growing plant and 
animal life is discussed. Focal length of lens, distance from camera to subject, 
size of subject, corrective angles and magnifications of results are shown to 
be vital factors in every variety of time-motion study, and recommendations 
for achieving optimal results are made. 



ARECISE MEANS of measuring moving 
objects is becoming an increasingly 
important phase of photography. There 
is a wide interest in studies of motion. 
Subjects range from growing plants and 
bodies to artillery shells in flight, and 
even to the measurement of the velocity 
of light itself. 

Photographs have been made of the 
human embryo from its conception, 
through birth, and eventually ending 
with the human body in death itself. 
It has been thus possible to measure 
rates of human growth over the complete 
life span, from the maximum of just 
before birth to the final, negative phase 
when the body becomes slightly smaller 
in old age. 

Time-lapse pictures of the budding 
and blossoming of a flower are another 
interesting application of motion photog- 



Presented on October 16, 1951, at the 
Society's Convention at Hollywood, by 
John H. Waddell, Industrial and Technical 
Photographic Div., Wollensak Optical 
Co., 850 Hudson Ave., Rochester 21, N.Y. 
(This paper was first received Nov. 24, 
1952, and released July 21, 1953.) 



raphy. In this case the exposure time 
will be short, but the frequency may be 
as low as once an hour to get a desired 
motion picture that can be used for 
visual observation and analysis. 

A popular subject today for such 
studies is the rate of growth of the fireball 
of the atom bomb. A typical series of 
pictures made for this purpose is shown 
in "The Effects of Atomic Weapons" 
(Atomic Energy Commission, Wash- 
ington, D.C., 1950). A picture fre- 
quency of about 8,000/sec was used in 
this instance. 

In order that precise measurements of 
motion may be made, certain primary 
requirements, and the terms describing 
them, must be understood, as well as a 
technique of reading the resulting films. 

In the determination of velocities, 
accelerations and the degree of move- 
ment from exposed film, the following 
must be known: (1) the focal length 
of the lens; (2) the distance from the 
camera to the subject; (3) the size of 
the subject; (4) corrective angles; and 
(5) the magnification of the reading or 
transcription system. 



24 



July 1953 Journal of the SMPTE Vol. 61 



Before entering any discussion of the 
photography of motion, an understand- 
ing of the meaning of velocity is impera- 
tive. Most observers think in terms of 
linear velocity only, in relationship to 
motion studies, but angular velocity is 
far more important photographically. 
One of the first questions to be asked 
is, "What is the angle of view or coverage 
of the lens?" This, indirectly, allows 
the photographer to calculate how far 
the subject will move during exposure 
and/or between exposures. 

Linear velocity is equal to distance 
divided by time. Projectiles in flight 
are measured in feet or meters per 
second, motor cars in miles per hour, 
and boats by knots, while plants and 
animals may be measured in inches per 
day, week or month. It is possible to 
photograph these assorted space-time 
relationships and to show them in the 
same space-time relationship. The tech- 
niques for photographing the various 
subjects however, must of necessity 
differ. 

Angular velocity technically is the 
quotient of angle divided by time. 
More simply, it is the distance the 
subject will move during the time of 
exposure in a given field size. 

If a projectile is moving at a linear 
velocity of 1000 fps and if the field size 
is 1 ft, the projectile will move 1 ft 
during an exposure time of 0.001 sec, 
or yV ft in 0.0001 sec. In 1 M sec. 
it will move but 0.001 ft, or 0.012 in. 
If the field size is increased to 100 ft, 
the image size with the same focal lens 
is about y^-Q what it was in the first 
case. The subject will travel as far 
as each exposure time given above, but 
the apparent image on the film is 
sharper because of its reduced size. 

With a picture-taking rate of 1000/sec, 
one picture would be secured with a 
1-ft field. With the 100-ft field, 100 
pictures would be obtained. 

In the instruction book issued for the 
Kodak High-Speed Camera, a formula 
is given for the determination of desirable 



Table I 



Focal length 

Of Idls 


Distance, camera to 
subject 


1 


in. 


so] 


.... 


(25. 


08ft) 


35 mm 


421 


4 in. 


(35. 


12ft) 


2 


in. 


602 


in. 


(50 


16ft) 


2* 


, in. 


752 


.5 in. 


(62 


71 ft) 


3 


in. 


903 


in. 


(75, 


24ft) 


4 


in. 


1204 


in. 


(100 


33ft) 


6 


in. 


1806 


in. 


(150 


50ft) 


10 


in. 


3010 


in. 


(250 


.8 ft) 


15 


in. 


4515 


in. 


(376 


.25 ft) 



camera speed (C.S.) for sharp pictures: 

cs = 40 X Speed of subject in ips 
Total width of subject field in in. 

In order to see how this works prac- 
tically in ballistics: 

Projectile speed, 2000 fps or 24,000 ips; 
Total width of field, 10 ft or 120 in.; 



G.S. = 



40 X 24,000 

120 
8,000 pictures/sec 



In the 0.005 sec, 40 pictures will be 
obtained. If the pictures are taken at 
14,000/sec, about 72 pictures will be 
obtained, requiring about 5 sec pro- 
jection time. 

If the field were 1-ft, 80,000 pictures/ 
sec would be required, while with the 
1000-foot field 800 pictures/sec would be 
adequate. 

The above formula does not give the 
movement of the subject image on the 
film during exposure. However, with 
the 10-ft field and with an 8mm camera 
taking double-width pictures, the film 
width is 0.4 in. Therefore, the re- 
duction is: 



(Field width) 120 in. 
(Film width) 0.4 in. 



300 times 



Table I gives the distance from the 
camera to the subject and the available 
lenses to secure this field width. 

It is to be observed that from each of 
these camera positions, the field size 
will be the same. And from the corn- 



John H. Waddell: Photography of Motion 



25 



parative standpoint, the depth of field 
can be the same. 

With this reduction in size, and with 
a velocity of 2000 fps, 4 pictures will 
be made per foot of travel of the pro- 
jectile. Therefore, the subject will travel 
during exposure: 



2000 x 



mo 



x 



0.0417 ft or 0.5 in. 



Fps X Reciprocal of X Exposure 
Picture-Taking Cycle Rate 
Rate 

= Movement of 
Subject 

Based on the 300 times reduction, the 
image on the film will move during 
exposure 1/300 of 0.5 in. or 0.00167 in., 
which is excellent for frame-by-frame 
analysis. 

To go to the other end of the scale 
to secure the opening of the flower or 
the growth of a plant, the same type of 
calculation is required. If a flower 
takes 4 days to open completely and a 
15-sec end sequence is required: 

15 sec X 24 pictures /sec = 360 pictures 

4 days = 5760 min 
5760 



360 



= 16, or 1 picture every 16 min 



One is able to control the exposure of 
time-lapse photography far more easily 
than the exposure in high-speed photog- 
raphy. 

A man hitting a golf ball, photo- 
graphed with a 10-ft field, makes an 
excellent subject at 1000 pictures/sec, 
while the impact of the club on the ball 
in a 4-in. field cannot be satisfactorily 
photographed at 14,000 pictures/sec. 

(1) Focal Length of Lens 

The focal length of the lens is nomi- 
nally the distance from the lens to the 
film plane when the lens is focused at 
infinity. There is one school of thought 
which believes that the effective focal 
length for measurement purposes should 
be based on the hyperfocal distance 
rather than the infinity focus. 



The comparative change in effective 
focal length (infinity focus) is given in 
Table II. 

Table II 



Nominal 
effective 
focal 
length, 
in. 


Maximum 
aperture 
of lenses 
calculated 
(/-stop) 


Hyperfocal 
distance 
at maximum 
aperture,* 
ft 


Correction 
to be added 
to effective 
focal length, 
in. 


1 


2.5 


33.3 


.00118 


35mm 


2.0 


79.1 


.00200 


2 


2.0 


166.7 


.00200 


2* 

3 


2.7 
2.5 


192.9 
300 


.00271 
.00250 


4 


3.5 


380.95 


.00351 


6 


4.5 


666.7 


.00451 


10 


4.5 


1851.9 


.00450 


15 


5.6 


3348 


.00560 



* With the lens focused on the hyperfocal 
distance, all objects from half the hyper- 
focal distance to infinity are in focus. The 
calculation for hyperfocal distance is 
based on: 

//o 
H = 



//number x 

The circle of confusion is assumed to 
be 0.001 in. 

The ASA standards on lens focal 
length allow a 4% deviation from 
nominal or marked focal length. All 
lenses to be used for measurement 
purposes, therefore, should be marked 
in the EF to the nearest tenth-millimeter 
or thousandth of an inch. 

It is to be pointed out that the focal 
length will also be a contributing factor 
in the angular field coverage. The 
expression "angular coverage" in this 
paper refers to either vertical or hori- 
zontal only, and not to diagonal. Most 
engineers follow the line of action in 
either the vertical or horizontal planes 
in measurement. 



tan 



\ Frame width 
Focal length 



It can easily be seen that the 4% 
variation will have a serious effect on 
angular coverage and this becomes 
more critical with longer focal length. 



26 



July 1953 Journal of the SMPTE Vol. 61 



Table III 



Temperature Fahrenheit 





-65 





70 


150 


Aluminum 


-.00186 


-.00097 


.0000 


+ .00111 


Brass 


-.00134 


-.00070 


.0000 


+ . 00080 


Invar 


-.000067 


-.000035 


.0000 


+ .000040 



(2) Distance From Camera to Subject 

The distance from the camera to the 
subject is one of the most confusing 
points in measurement and designation 
of focusing scales. ASA has established 
a standard marking on the camera, 
"Film Plane" being designated by a 
circle with a vertical line passing through 
it. It must be realized, however, that 
the term "Film Plane" may not mean 
much to an average user, and this has 
been modified on Fastax cameras to 
read "Measure subject distance from 
here," with the same bisected circle 
designation. The allowable deviation 
is then 2 line widths from the nominal 
marking on the lens. 

Furthermore, on the focusing scale 
there should be an over-run beyond 
the infinity marking. Most camera 
operators do not feel satisfied unless 
they can go beyond infinity and then 
come back to infinity when they are 
focusing. 

No reliance should be placed on 
focusing scales in extreme limits of 
temperature, the effects of extreme heat 
or cold becoming more noticeable with 
longer focal-length lenses. The aerial 
image should be the standard of focusing 
under these conditions. 

Table III illustrates the change in 
lens-tube length per unit length for 
temperature ranges specified by the 
military forces and those actually occur- 
ring in the United States. 

It is obvious that if a 10-in. lens tube 
is used, the back focus will be pushed 
.019 in. behind the normal film plane 
with an aluminum tube at 65 F while 
it will be pulled 0.011 in. ahead of the 
film plane at +150 F. The above does 



not take into consideration what takes 
place in the lens cells themselves. They 
should be constructed with invar separa- 
tors. 

Besides the focusing scale on lenses 
for measurement, there should be a 
temperature-compensating scale. This 
is doubly imperative because lenses in 
high-speed photography are in many 
cases used "wide open." It is also 
imperative that the materials used for 
lenses have a minimum coefficient of 
expansion and that they should not 
have a black external finish. 

Many high-speed photographers are 
using infrared filters to accentuate the 
sky, particularly in missile work. This 
changes the back focus. The rule for 
photographing in the near infrared is 
to increase the back focus 1/88 the 
normal focal length. There is no effect 
on the back focus with visible light. 

There is another disturbing factor in 
measurement that is frequently over- 
looked. It is that of atmospheric con- 
vection currents. Most survey work on 
the desert is done from midnight until 
sunrise. The currents or "jitter" have 
a very disturbing effect on camera focus 
and on the photographic results obtained. 
Pictures taken with Askania cameras 
and standard-speed motion-picture 
cameras at elevations of less than 20 
are unique in many respects, but prac- 
tically useless for a precision measure- 
ment. This effect is minimized by 
elevation and altitude and by shortening 
of exposure time. High-speed motion 
pictures are practically free from this 
effect. The greater the distance from 
object to the camera, the more "atmos- 
pheric jitter" will be present. 



John H. Waddell: Photography of Motion 



27 



(3) Size of Subject 

The size of the subject can be used for 
computation of velocities and field size. 
The magnification is 



M 



D - F 



, where 



D = distance of object to film plane 
F = focal length 

The above formula is approximate. 
A deviation of the exact formula gives 
the following relationships: 



triangle requires the solution of two 
triangles in the following steps: 

A =30 angle of view 
A' = A" = 15 
B = 95 
G = 55 

D =20 angle of flight 
b' =100 distance of center of field 
a' + a" = a path of the subject 

In triangle I 



sin A' sin B 



In triangle II 



Reduction is the inverse ratio from 
the magnification factors given above. 

(4) Corrective Angles 

The angle of the motion to the camera 
is important from a number of points 
of view. 

The amateur cinematographer usually 
learns the hard way that a child on a 
swing gives the best stroboscopic effect 
when the camera is 90 to the direction 
of the swing. It becomes less at 45 
and an even picture is obtained head-on. 
"Panoraming" makes an audience 
dizzy. But as the camera is focused on 
a moving subject and follows it, the 
subject is sharp. This is a practice 
followed by press photographers and 
newsreel cameramen. 

There are two major types of angular 
problems which are typical of field 
installations: that in which the distance 
to the center of the field is known; and 
that in which the distance is known to 
the point where the subject will enter 
the field. Trigonometry solves these 
problems as follows: 



sin A 



sin B 



c 
sin 



In Fig. 1, the case where the distance to 
the center of the field is known, this 



Solving 



and 



Therefore 



sin A" sin G 

a' 100 

sin 15 sin 95 

a' = 26ft 
a" 100 



sin 15 sin 55 
a" = 31.5ft 

a' + a" = 57.5ft 



And now, the second problem, as shown 
in Fig. 2: 

A =30 angle of view 

A' = A" = 15 

B = 95 

G = 55 

D = 20 

d = 100 

cos A" = - 
c 

ico 100 

cos 15 = - 
c 

100 



= 103.5 ft 



.966 

c sin A 
sin c 

103.5 X sin 30 



sin 55 ' 



63ft 



28 



July 1953 Journal of the SMPTE Vol. 61 




Fig. 1. Flight path where subject bisects 
known distance from camera. 




Fig. 2. Flight path when distance is 
known where subject enters field. 



The above assumptions are based on 
optical systems which produce distortion- 
free films. In order to check the dis- 
tortion of the system, a sheet of cross- 
section paper can be photographed and 
then the distance between lines checked 
with a microscope over the whole field. 
The objectives for measurement selected 
must be good ones however. 



(5) The Reading System 

In the reading of the film, the pro- 
jection optics should be equal in resolu- 
tion and field flatness to the exposing 
optics. In order to cut costs of manu- 
facture, inferior optics are often used, 
as is sometimes apparent in slide and 
motion-picture projectors. The pro- 
jection lens on the time-and-motion 
study projector should be a photographic 
objective, because many users project 
their films frame by frame, particularly 
those taken with high-speed motion- 
picture cameras. The focal length of 
the lenses should be accurately marked, 
so that the user can make good measure- 
ments. 

In many microfilm readers, the same 
condition exists. It is becoming impera- 
tive that the magnification factors be 
calibrated for the study of motion. The 
finest of cameras will be wasted if the 
resultant film is studied through poor 
reproduction optics. 

One manufacturer provides a test 
film taken with the camera when ready 
for delivery. The film consists of a 
National Bureau of Standards Resolu- 
tion Test Chart as photographed with 
that particular camera. The test chart 
shows resolving power up to 56 lines/ 
mm. It has been demonstrated many 
times that the best resolution that can 
be shown on some types of optical 
comparators and ground-glass screen 
projectors is a resolving power of one- 
half or less than that obtained through a 
straight optical system. A resolution of 
56 lines/mm is approaching the limit of 
many high-speed panchromatic emul- 
sions. 

Milk-bottle glass lenses are a cheap, 
time-wasting and worthless means of 
examining fine, accurately made films. 

Exposure time should be critically 
examined. Theoretically, exposure 
should be based on a square-top wave. 
The exposing device should open instan- 
taneously, remain open for the desired 
time and then close instantaneously. No 
devices yet available follow this pattern. 



John H. Waddell: Photography of Motion 



29 



High-speed gas-discharge tubes have 
a decay time, focal-plane shutters move 
across the film, barrel shutters and ro- 
tating prisms follow a sine wave, me- 
chanical shutters have both opening and 
closing time. The fastest-operating 
shutters are the piezo-electric or electro- 
optical shutters, which operate off a 
single pulse such as a radar pulse. 

An interesting question was raised by 
one high-speed photographic user. He 
was using a spark for schlieren photog- 
raphy. The photographs showed that 
the schlieren picture exposure was 1 
jusec. A calibration was desired, and a 
streak picture of the spark discharge 
was therefore made. It was found that 
the discharge required 100 jusec to take 
place, but that the actinic photographic 
exposure took place in only 1 jusec. 

In the Fastax camera, the approxi- 
mate exposure time is given at ^ times 
the reciprocal of the picture-taking 
rate. At 1000 pictures/sec, the ex- 
posure time is 0.17 msec; at 15,000 
pictures/sec, 12 jusec. With the Edger- 
ton flash unit designed for the Kodak 
and Fastax cameras, the exposure time 
is 1-J- Atsec. With the rotating prism, 
the image sweeps with the film and a 
highly resolved image is obtained. If 
the flash unit is used without the prism, 
the image is smeared by the following 
amounts : 



image smear, the data are given below 
to show the time of exposure and 
maximum velocity to produce this 
limit. 



Film velocity, 

fP* 
1 \-lisec flash 

5 

50 

100 

200 

1000 

20-fjisec flash 
5 

50 

100 

200 

1000 



Image movement during 
exposure, in. 

0.00009 

0.0009 

0.0018 

0.0036 

0.018 



0.0012 

0.012 

0.024 

0.048 

0.240 



Exposure, sec 

0.000001 

0.00001 

0.0001 

0.001 

0.01 

0.1 

1.0 



Film velocity, ips 

250.0 
25.0 
2.5 
0.25 
0.025 
0.0025 
0.00025 



Therefore, if a limit of 0.00025 in. is 
placed as the upper tolerable limit of 



It can easily be seen that for film 
velocities of more than 20 fps, image 
compensation is useful. 

With focal-plane shutter, 1/1,000 in. 
is the lower useful limit at present; 
with the compound shutter 1/800 in. 
is the lower limit while other shutters 
fall in this grouping. The electric spark 
has a low limit of about T ^ jusec, while 
the piezo-electric effect can be operated 
at 1/1,000 /isec. 

Back in 1880 Muybridge used multiple 
cameras to get the trotting horse pic- 
tures. Multiple cameras are used today 
to secure time resolution to a high 
degree, but they cover the same field 
of view. 

In such an arrangement, all the 
cameras must be receiving the same time 
signal to drive the gas-discharge (neon) 
timing light or the spark. Each light 
must begin to function some time after 
the cameras have started, so that zero 
time is established on all films. With 
rotating-prism cameras driven by series 
motors, the prisms are all in random 
positions. It is possible to secure 
measurements to an accuracy of 1 /zsec 
by using 14 cameras at 16,000 pictures/ 
sec and assuming the exposure time of 
10 jusec per picture. 

By reading the leading edge of the 
motion, and with milli-second timing 
marks establishing the angle of prism 
rotation with respect to the next camera, 
the readings from 14 films will give the 
microsecond accuracy. 

A formula for the establishment of 



30 



July 1953 Journal of the SMPTE Vol. 61 



number of cameras with random shutter 
positions, constant exposure times, and 
other factors, is given in a paper by 
Wilkinson and Romig.* 

The use of 10 or 20 less expensive 
cameras with high resolution will often 
produce space-time resolution over a 
much longer period of time than will a 
single ultra-high-speed camera with fair 
resolution or with limited picture- 
taking capacity. 

Another extremely valuable aid in 
the photography of motion is the use of 
stereoscopy. The perception of depth 
achieved through the two eyes of human 
vision assists materially in the analysis 
of space motion. In some cases, people 
born with one eye learn to visualize 
this differentiation of space, but it is, 
of course, far more readily observed 
with the use of two eyes. Stereoscopy, 
with an interpupillary distance of ap- 
proximately 2 inches can be prac- 
ticed up to distances of 1000 to 2500 ft. 
Greater distance perception can be 
obtained by artificially increasing the 
interpupillary distance to a base of from 
6 in. to 20 ft or more. Where the broad 
base is used, however, there should be 
nothing in the foreground. 

A number of devices have been used 
in stereoscopic photography. The most 
common are twin-lens cameras with the 
2-j-in. interpupillary distance; single- 
lens cameras with mirror or prism beam 
splitters (this includes the use of wedge 
prisms) ; beam splitters with individual 
lenses; single cameras and single lenses 
moved through a known interpupillary 
distance (this latter method is used in 
aerial photography). There are ad- 
vantages and disadvantages to each of 
the above methods. In order to broaden 
the base of high-speed motion picture 
photography, there have been stereo- 

* Roger Wilkinson and Harry Romig, 
"Space-time relationships with multiple- 
camera installations," presented on Oc- 
tober 8, 1952, at the Society's Convention 
at Washington, D.G. Early publication 
in the Journal is planned. 



scopic devices designed to assist in ihr 
analysis of motion. 

As a further aid in the study of mot i< >i i . 
reticles and fiducial marks arc used to 
help establish the base lines for measure- 
ment. In the case of intermittent and 
still photography, the aperture plate 
may be notched, or crosshairs may be 
placed in the plane of the image. In 
the case of high-speed motion-picture 
cameras, there has been designed a 
system which consists of moving the 
objective lens ahead of the point .H 
which it would normally be used. I In- 
image from the objective lens is laid 
down on a collecting lens which has a 
reticle engraved upon it. A one-to-one 
relay lens system then lays the image 
down at the film plane. Because the 
image is in a reverse position, compared 
with the normal photographic pro- 
cedure, projecting the films is accom- 
plished by putting a roof prism in front 
of the projection lens to get the picture 
back into normal orientation. 

The measurement of the film for 
motion remains to be discussed. Pro- 
jectors are normally used for measuring 
purposes in the case of motion-picture 
film. The projector will, of course, 
have a certain amount of natural jump, 
and therefore measurement by this 
means should be confined to qualitative 
factors only. 

Frame-by-frame analysis of the in- 
dividual pictures is far more important. 
This is aided by fiducial marks, often 
on the original film. Today most 
projectors of this type back-project the 
film onto a ground-glass screen. Where 
the subject is small, however, the grain 
structure of the screen may interfere 
seriously with the ability to measure 
the film. As was mentioned above, the 
object may actually move during ex- 
posure, and, therefore, it becomes quite 
difficult to establish a point of measure- 
ment. The ordinary procedure in such 
a case is to measure the leading edge of 
the smear. Where wide-angle lenses 
are used, or where there is no change in 



John H. Waddell: Photography of Motion 



31 



the magnification of the projection 
system, templates can be designed and 
used to cover the necessary distance or 
angular calibrations. 

The ideal system would be to take 
films which have fiducial marks (used 
with intermittent cameras) or projected 
reticles (used with continuous cameras) 
and project the image at 10 X magni- 
fication onto a clear-glass screen. Use 
a mark (engraved) on the clear screen 
for focusing the eyepiece, and fiducial 
or reticle marks for the superimposition 
of the projected film image. A 5 X 
eyepiece on a pantograph arrangement 
may then be used to measure the position 
of the test object on the film. The 
pantograph is so arranged that the 
* and y values from the center may 
be noted on a counter. Alternatively, 
a prepared linear scale may be engraved 
on a clear-glass screen at any desired 
footage or angular base. 

If the camera is reducing the original 
subject 100X and the projector is 
working at 50 X magnification, it is 
apparent that the subject is one-half 
normal size, an easily measured image. 
Even if there is motion in the subject, 
the "fuzzy" leading edge will still be 
a good point to measure from picture to 
picture. The picture or subject does 
not have to be frozen for accurate 
readings. 

Another instrument valuable for 
measurement of motion is the densi- 
tometer. This instrument is used for 
brightness or intensity measurements. 
It is possible to make very good measure- 
ments with the frame-by-frame or streak 
cameras by correlating time and density 
measurements from any part of the 
film. Flames, explosions, and detona- 
tions are typical subjects for these 
studies. 



This technique is not valid for reversal 
film, but only for negative. In a re- 
versal film, with a controlled second 
exposure, the processing will alter the 
desired result. 

H&D strips are placed on the negative 
or on a strip of negative material of the 
same emulsion number as the test film. 
A test negative is made of a subject of 
known brightness such as the sun. It 
may be necessary to reduce the intensity 
with neutral-density filters in order to 
place it on the midpoint (such as a 
density of 1.2) of the straight-line portion 
of the H&D curve. A plot is then made 
of time of exposure (preferably to the 
millisecond) and obtained density. That 
is the starting point even with density- 
correcting filters. For more intense 
incandescent points, heavier filters are 
used; for subjects of moderate bright- 
ness, more transparent filters, or none 
at all, may be employed. Three color- 
separation negatives may be made this 
way, and individual color prints made 
from any point on the film, providing 
zero time marks start after the film has 
started, and the same oscillator is used 
for timing purposes. By using sharper- 
cut color filters, measurements can be 
made in any portion of the spectrum 
from the near-ultraviolet to the infrared 
for the broad-band spectral analysis of 
flame components. 

The reading of films for measurement 
of motion is oftentimes quite laborious, 
but it pays dividends from the standpoint 
of accuracy. 

In conclusion, then, it may be said 
that the photography of motion is a 
fairly simple proposition if one takes 
into consideration the space-time rela- 
tionship, the rate of growth, angular 
velocities, and endeavors at every step 
to ensure accurate measurements. 



32 



July 1953 Journal of the SMPTE Vol. 61 



The BRL-NGF Cinetheodolite 



By SIDNF.Y M. UPTON and KENNARD K. SAFFKK 



A number of incomplete Askania cinetheodolites are being extensively re- 
habilitated and modified under a joint program of the Navy Bureau of Ord- 
nance and the Army Ordnance Ballistic Research Laboratories. New features 
include improved bearings, data circles, complete replacement of all mount 
components except carriage castings, a Mitchell high-speed camera movement 
operating synchronously at 16, 32 or 64 frames/sec, 500-ft magazines, and 
telescopic optical systems of 60-, 96-, 144- and 180-in. focal lengths. 



A HROUGH a joint program of the 
Ballistic Research Laboratories of the 
Army Ordnance Department, and the 
Naval Gun Factory under the direction 
of the Navy Bureau of Ordnance, the 
modification of a group of existing in- 
complete Askania cinetheodolites has 
resulted in a new, improved and radi- 
cally modified cinetheodolite. At the 
present time these new instruments are 
in the process of construction and the 
first prototype model is nearing comple- 
tion. 

Many of the features planned for this 
instrument have previously been tried 
out in other instruments but several pro- 
posed features have yet to be actually 
field tested. 

The improved accuracies of bearings 



Presented on May 1, 1953, at the Society's 
Convention at Los Angeles by Sidney M. 
Lipton (who read the paper), Bendix 
Radio Communications Div., Bendix Avia- 
tion Corp., Baltimore, Md. (formerly of 
Ballistic Research Laboratories, Aberdeen 
Proving Ground, Md.), and Kennard R. 
Saffer, U.S. Naval Gun Factory, Washing- 
ton, D.C. 
(This paper was received on May 4, 1953.) 



and circles have already been demon- 
strated in similar cinetheodolites fur- 
nished to the U.S. Naval Ordnance Test 
Station, Inyokern, Calif. Long focal- 
length telescopic systems, and high 
variable-speed cameras with large film 
capacity have been used at White Sands 
Proving Ground, Las Cruces, N.M., in 
similar cinetheodolites. The use of a 
synchronously operated multispeed cam- 
era, a range of quickly changeable long 
focal lengths, and the use of the parti- 
cular type of target-acquisition system 
employed here have not yet been field 
tested. The configuration of the camera 
drum, the incorporation of a standard 
high-speed Mitchell movement, the pro- 
vision for phasing in the shutter opera- 
tion with a central signal, the arrange- 
ment of the 500-ft magazines, the provi- 
sion for a quick field check of infinity 
focus and collimation and the use of 
standard-frequency power for the motor 
drive are new as far as the WSPG range 
cinetheodolite instrumentation is con- 
cerned. 

This instrument is planned for use at 
the White Sands Range for both Army 
and Navy projects and the design fea- 



July 1953 Journal of the SMPTE Vol. 61 



33 



AZIMUTH WORMWHEEL 



AZIMUTH SCALE SUBASSEMBLY 



MAIN AZIMUTH 
BEARING 



LEVELING SCREW 




DIA. CHROME 
STEEL BALLS 



SLIP RING SUBASSEMBLY 
( 24 RINGS ) 



Fig. 1. Mounting-base assembly. 



tures of this cinetheodolite have reflected 
the particular requirements of this 
range. 

It was found that the existing German 
design of the main azimuth bearing and 
the elevation trunnion bearings were not 
suitable for photographing fast moving 
objects. Specifications were set forth 
by ordnance test stations requiring a 
theodolite to train in azimuth about its 
vertical axis within a tolerance of plus or 
minus five seconds of arc. Likewise the 
same tolerance was specified for the rota- 
tion of the camera drum about the hori- 
zontal axis. The glass scales used for 
recording angles of azimuth and eleva- 
tion were required to be engraved to an 
accuracy of two seconds of arc. 

It was also evident that the picture 
rate of the German Askania camera of 4 
frames/sec was insufficient. Likewise, 
the German 30.0- and 60.0-cm focal- 
length photographic-objective lenses were 
not capable of photographing targets at 
long range. 

Previously designed azimuth bearings 
for this instrument, which were success- 
fully used at the U.S. Naval Ordnance 
Test Station, were found to meet these 
required tolerances. The cross-sectional 
area of the bearing for this instrument 
was increased for ease of manufacture. 

Figure 1 shows a cross-section view of 
the main azimuth bearing and the center 
spindle assembly. 



(a) The azimuth bearing consists of an 
inner and outer race. The outer race is 
divided into two parts separated by a 
spacer which is ground to the proper 
thickness to eliminate any shake between 
the balls and the race. 

(b) The center-spindle assembly is 
fitted to the base. The vertical axis of 
the instrument is established by the rota- 
tion of the spindle on precision ball 
bearings. These bearings have an 
ABEC-7 rating. From this axis the out- 
side diameter of the main azimuth bear- 
ing seat is machined concentric within 
0.0002 in. 

(c) After the bearing is assembled and 
the top and bottom surfaces of the com- 
plete bearing are checked for parallelism, 
it is then placed in the base. The bear- 
ing seat on the base is scraped so that the 
outer race can be properly seated and 
secured without introducing any rota- 
tional error. The inner race is seated to 
the rotatable carriage in a like manner 
and then secured. The rotational force 
is transmitted from the base to the 
carriage through 68 f-in. diameter 
chrome steel balls. 

(d) The azimuth scale mount is then 
fitted to the center-spindle housing on a 
tapered surface. With the glass scale 
loosely placed in its mount, the assembly 
is rotated about the tapered fit. By 
means of eight concentric marks on the 
glass scale, a concentricity check is made 



34 



July 1953 Journal of the SMPTE Vol. 61 



on each mark viewed through a 100- 
power microscope. After the scale is 
adjusted truly concentric with the verti- 
cal axis of the instrument, the scale re- 
tainer is secured and the glass scale ce- 
mented in place. By this method of 
assembly the concentricity error between 
the glass scale and the main azimuth 
bearing is held to an absolute minimum. 
The rotatable carriage is mounted to the 
inner race of the main azimuth bearing 
by a close pilot fit which is machined 
concentric to the rotation of the azimuth 
bearing. A coupling arrangement is 
provided for the mounting of the car- 
riage to the center spindle to offset 
possible binding between the carriage, 
which finds its center about the main 
azimuth bearing, and the vertical axis of 
the base. 

(e) Twenty-four slip rings are pro- 
vided to allow for continuous rotation in 
azimuth. The brush-holder mount is 
designed so that the replacement of 
brushes would be relatively simple. 
Metal brushes are used to keep the volt- 
age drop to a minimum. Electrical con- 
nectors are provided on the underside of 
the base to supply power for the operation 
of the camera and other electrical units. 

(f) The carriage assembly trains in 
azimuth about the vertical axis by means 
of a worm-and-gear drive operated by a 
handwheel. The handwheel subassem- 
bly provides a two-speed gear ratio, 
namely, 1 rotation of the instrument per 
one turn of the handwheel in slow speed 
and 4 per turn in high speed. To 
change from one ratio to another, the 
handwheel is either pulled or pushed in 
an axial direction. 

(g) The azimuth and elevation internal 
glass scales are made of plate glass to 
Bureau of Ordnance specifications. They 
are engraved every one-half degree to 
within an accuracy of two seconds of arc. 

The azimuth scale mount can be 
rotated by means of a spring-loaded 
clutch enabling the operator to align the 
zero point on the scale to any desired 
position. 



Figure 2 is a cross-section view of the 
assembled carriage and slip-ring assem- 
bly. 

(a) Microscopes of 30-power are pro- 
vided on the azimuth and elevation sides 
of the instrument. When the position- 
ing lever is depressed, the microscope is 
inserted into the optical path of the scale- 
projection system. This enables the 
operator to read the internal scales 
directly in degrees and minutes. A 
spring tension on the positioning lever 
requires the operator to hold the micro- 
scope in a reading position. As soon as 
pressure is released from the lever the 
microscope is retracted from the optical 
path of the scale-projection system. 
This feature assures an uninterrupted 
projection of the scale readings to the 
film plane when the camera is in opera- 
tion. The azimuth and elevation angles 
are simultaneously photographed with 
the target. The internal scales are 
illuminated by flashlamp units which are 
synchronized with the camera shutter 
so as to allow proper illumination for 
projecting the scale readings to the film 
plane. The advantage of photographi- 
cally recording the azimuth and elevation 
angles with the target is that recording 
errors due to rate of change in tracking 
error are eliminated. This method pro- 
vides accurate data for determining and 
recording the trajectory of the target. 

(b) The camera drum rotates in preci- 
sion ball bearings about the horizontal 
axis by means of a worm-and-gear drive 
operated by a handwheel. The hand- 
wheel subassembly is provided with the 
same gear ratios as those in the azimuth 
drive. The ball bearings used for the 
rotation of the camera drum about the 
horizontal axis have an ABEC-9 rating. 

(c) The camera-drum trunnions are 
machined concentric to the horizontal 
axis. After the drum is assembled in the 
trunnion bearings on the carriage, the 
horizontal axis is checked for parallelism 
to the rotation of the main azimuth 
bearing. The elevation glass scale is 
then mounted on its housing. By means 



Lipton and Saffer: BRL-NGF Cinethcodolitc 



35 




36 



July 1953 Journal of the SMPTE Vol. 61 




Fig. 3. Side elevation of camera and main optical system (60-in. E.F.L.) 
with focusing attachment. 



of eight concentric marks on the glass 
scale, it is centered about the horizontal 
axis. The scale retainer is then secured 
and the scale is cemented in place. 

(d) The guiding telescope is a mo- 
nocular right-angle type with inter- 
changeable eyepieces to provide for 
magnification of 12- and 20-power. 
The eyepieces can be focused from 2 to 
+4 diopters. The two eyepieces can be 
interchanged by pulling one of the com- 
plete assemblies from the body of the 
telescope. By means of a piloting fit 
and a positioning dowel, the other eye- 
piece assembly can be inserted into the 
telescope body. It is held in place by 
three spring-loaded detents and is se- 
cured by a lock screw. 

Crossline illumination is provided for 
the reticle. The light intensity can be 
varied by a rheostat for sighting under 
adverse light conditions. 

The complete telescope weighs 7 Ib 
and has a moment of 42 in-lb about the 
horizontal axis. The telescope mount- 
ing bracket is counterbalanced to offset 
this moment. 

The optical characteristics of the tele- 
scope are as follows : 



Magnification 
True field 
Eye distance 
Exit pupil 



Low Power 

12X 

5 

24 . 5 mm 

5.0 



High Power 

20 X 
2 45' 
15.0 mm 
3.0 mm 



When the field location of these 
instruments is a considerable distance 
from the starting point, the target will 
not be visible initially to the tracker due 
to differences in elevation, atmospheric 
conditions or reduction in size of image 
caused by long horizontal lines of sight. 

To enable the tracker to follow the 
target even though not visible, a remote- 
indication system will be set up in the 
field to transmit to these instruments elec- 
trical signals which will be a function of 
the relative position of the target. 

The reception of such signals at the 
instrument will result in a galvanometer- 
pointer deflection, visible to the tracker. 
By tracking the instrument properly, 
each tracker will tend to keep this pointer 
deflection at the zero mark. This will 
mean that the target is in his field of 
view. By occasionally checking in the 
guiding telescope, the tracker will even- 
tually sight the target and continue 
tracking thereafter visually. 

The main optical system, shown in 
Figs. 3, 4 and 5, consists of a Cassegrain- 
ian telescope. There are four focal 
lengths available: 60, 96, 144 and 180 in. 
Figure 3 shows the layout for the 60-in. 
system. The clear aperture of the main 
mirror is ?{- in. and its focal length is 24 
in. The main mirror is held in an ad- 
justable cell mount in which tilting of the 
mirror is possible so that it may be 
aligned correctly with reference to the 



Lipton and Saffer: BRL-NGF Cinetheodolite 



37 




Fig. 4. Optical diagram for (above) 144-in. and (below) 180-in. E.F.L. system. 




38 



Fig. 5. Plan view of camera and optical system (96-in. E.F.L. ). 
July 1953 Journal of the SMPTE Vol. 61 



film plane and the secondary mirror. 
The secondary mirrors are mounted in 
cells which are assembled in holders in 
which tilting and translation along ih< 
optical axis can be effected in small in- 
crements by means of setscrews, a ball- 
and-socket joint, bearing surfaces and 
fine threads. Movements along the axis 
may be controlled and repeated to 0.001 
in. by means of a vernier screw. The 
final position of the mirror is then 
established by a locking nut. The sec- 
ondary mirror assembly is fitted into a 
small central cylinder, web-supported, 
which is an integral part of an aluminum- 
alloy housing. This housing is a sepa- 
rate section of the main telescope tube 
which may quickly be removed and ex- 
changed for another similar housing con- 
taining a different secondary mirror pro- 
viding a different equivalent focal length 
for the main optical system. Once each 
secondary mirror has been adjusted and 
collimated with the main mirror, remov- 
ing it with its housing and later replacing 
it, when necessary, should not change its 
previous position since locating rings and 
a key will re-position it to a few thou- 
sandths of an inch of its previous location ; 
the locating rings are hard steel inserts 
which prevent translation, the key pre- 
vents rotation, and a mating steel butting 
surface maintains the correct distance 
from the main mirror. 

This secondary aluminum-alloy hous- 
ing is a casting designed to fit a particular 
secondary-mirror assembly; each in- 
strument will have four different second- 
ary-mirror and housing assemblies. 

In the field, the instrument operator 
may determine the correct infinity focal- 
point setting of the secondary mirror by 
means of an autocollimating type 
arrangement which he can quickly 
assemble and disassemble. Figure 3 
illustrates this apparatus, which consists 
of an optical flat, a mirror, reticle and 
prism arrangement, a 2-w zirconium-arc 
source and a viewing microscope with a 
40-mm objective. 

An 8-in. optical flat in an adjustable 



cell-holder assembly is mounted on the 
end of the secondary housing. A br.n k-i 
containing the mi< ms< ope. minm. 
reticle and prisms is inserted in i lie- 
camera drum .md locked into jxjsition. 
The zirconium-arc lamp is connected 
into position, so that its light is directed 
through the prisms and illuminates the 
reticle. The light goes through the main 
mirror system to the optical flat and then 
back again through the main mirror sys- 
tem where an image of the reticle is 
formed near the illuminated reticle pat- 
tern. After focusing the microscope on 
the illuminated reticle, the operator then 
translates the secondary along the optical 
axis until the image of the illuminated 
reticle is also in focus. For an object 
distance other than infinity, the second- 
ary mirror is then moved an addi- 
tional precalculated distance away from 
the main mirror. In this manner, the 
optical system may be checked each 
time before use, if, for example, tem- 
perature differences are such as to cause 
expansion or contraction of the structure 
between mirrors. 

The main tube has an open lattice- 
work construction consisting of end 
flanges of aluminum alloy and connect- 
ing thin-wall steel tubing (0.032-in. 
wall). The deflection of this main tube, 
assembled with a secondary mirror hous- 
ing in operating condition, has been 
measured and found to be 0.001 in. from 
vertical to horizontal position. This is a 
systematic error which may be corrected 
for in the final reduction of the film data. 

Openings have been provided in the 
main tube, near the main mirror end, to 
allow for removing the mirror cell and 
also for inserting the main mirror cover. 

The entire main optical-system assem- 
bly, without the magazines attached, 
weighs 32 Ib and exerts a moment about 
the trunnion centerline of 240 in-lb. 
With magazines loaded (total of 500 ft of 
film), these quantities become 40 Ib and 
360 in-lb. 

Counterbalancing of this system is 
effected by the camera-drum housing 



Lipton and Saffer: BRL-NGF Cinetheodolite 



39 



Table I. Main Optical System Characteristics. 



Effective focal length, in. 60 
Amplification 2 . 5 
Distance between primary and second- 
ary, in. 15.786 
Area obstructing primary aperture, sq in. 13. 30 
Net primary area, sq in. 36. 18 
Secondary clear aperture, in. 3.00 
Ratio of central obstruction diameter to 

primary diameter, % 51.9 
Ratio of central obstruction area to pri- 



96 
4.0 

18.250 

9.18 
40.31 

2.10 

43.1 



144 
6.0 

19.893 
6.66 

42.83 
1.51 

36.7 



180 

7.5 

20.618 
5.47 

44.01 
1.24 

33.3 



mary area, % 
Net focal ratio 


26.9 
8.84 


18.5 
13.41 




13. 
19. 


5 
51 


11.1 
24.06 


Clear aperture of primary 
Area of primary 
Focal length of primary 
Distance of film plane behind primary 
Diameter of image field at film plane 


7, 
49 
24. 
4 
1 


.9375 

.5 

,75 
062 


sq 


in. 
in. 
in. 
in. 
in. 





design and by external counterweights. 
The semicylindrical shape of the camera 
drum and its point of suspension on the 
trunnion axis place most of its weight 
behind the trunnions. The camera- 
drum covers are of steel while the drum 
itself is aluminum alloy; these covers 
also help in counterbalancing. 

Figure 4, showing the arrangement of 
the 144-in. and 180-in. focal-length sys- 
tems, shows also a typical ray tracing. 
A light shield is used both at the main 
mirror and at the secondary mirror to 
prevent stray light from entering the 
system. These shields are designed to 
use as much light-collecting area of the 
main mirror as possible. 

Table I, giving the main optical- 
system characteristics, shows the amount 
of light which is obstructed because of the 
secondary mirror cell, its supporting 
structure and the light shields for the 
different secondary mirrors. The effec- 
tive focal ratios are 8.84, 13.41, 19.51 and 
24.06. 

Figure 5, with the 96-in. focal-length 
system, shows the film path and the 
camera layout. The size of the image 
field at the film frame is 0.7 in. square. 
The camera drum contains the camera 
mechanism, the motor and gear drive, a 



timing-lamp housing, a frame counter, a 
gaseous discharge tube (Edgerton lamp) 
and a lamp trigger pickup and amplifier. 

The magazines are placed outside the 
drum, one on either side of the main 
tube, so that it is possible to plunge the 
instrument, or turn the main tube and 
drum through an elevation angle of 180. 
Each magazine can hold 500 ft of 35mm 
film. Laboratory tests have indicated 
no appreciable increase in torque when 
the film roll is in a horizontal position in 
the magazine, when the film edge slides 
on the inner surface directly or rests on a 
thin aluminum disc which revolves with 
the film roll. The take-up magazine is 
equipped with a 1/40-hp universal 
motor which operates between approxi- 
mately 600 and 1000 rpm; the connec- 
tion between the motor shaft and maga- 
zine shaft is through a 1 :3.5 pulley ratio 
using a Gilmer timing belt. This motor, 
when stalled under these conditions, does 
not heat up excessively. 

The camera mechanism is a standard 
Mitchell high-speed 35mm movement. 
This has been left assembled in its hous- 
ing which has been stripped down, 
eliminating such features as are not re- 
quired in this application, such as rack- 
over inserts and doors. Additional com- 



40 



July 1953 Journal of the SMPTE Vol. 61 



I/U 

ar 

I/8S 

1/315 
1/40 




a^s 



SPEED - FRAMES I 
TEMPERATURE AT TIME OF TEST 

eo 4* 



Fig. 6. Horsepower requirements for 
35mm Mitchell high-speed movement 
at ambient and low temperatures. 



Fig. 7. Horsepower requirements for 
35mm Mitchell high-speed movement 
operating at 32 frames/sec. 



ponents have been eliminated or modi- 
fied; the differential unit for shutter 
movement has been omitted ; the shutter 
opening will be varied in 15 increments, 
while the movement is stationary, by 
means of a knob and a series of locating 
slots. The shutter shaft has been short- 
ened. Some of the input gears have 
been eliminated and new gears with a 
particular ratio added. The camera 
box is positioned on its side, relative to 
its normal position. The film entry 
opening has been cut out to the edge of 
the camera box and a similar opening 
has been placed on the opposite side. 
The film enters and leaves in an edge up 
position. The holddown-roller assem- 
bly which holds the incoming film against 
the main drive sprocket has been modi- 
fied to include a double pip-time lamp 
housing. The buckle switch has been 
shifted in location relative to the take-up 
side of the main film-drive sprocket. 
Additional guide rollers have been placed 
in the feed and take-up sides about the 
film-drive unit for proper guidance of the 
film. 

The main drive motor is located in the 
lower compartment of the camera drum 
and is supported in a bracket in which 



FLASH LAMP TRIGGER AMPLIFIER 




FRAME COUNTER- 
MAIN DRIVE MOTOR 



Fig. 8. Front elevation of camera drum. 



the outer motor-housing ends are held in 
bearings ; by means of a gear connected 
on one end of this housing and a mating 
gear and knob, the latter located outside 
the drum, the motor frame may be 
rotated and locked. The motor is 3| 
in. in diameter by 4 in. long. Its out- 



Lipton and Saffer: BRL-NGF Cinetheodolite 



41 




Fig. 9. Prototype of main tube assembly and camera drum. 



put shaft is connected to a small gear- 
box which is in turn connected to the in- 
put of the camera gear mechanism. 

The design has been arranged so that 
either of two types of motors may be 
used. The first or preferred type is a 
motor now in the process of develop- 
ment. It is a multifrequency synchro- 
nous motor of approximately 1/8-hp 
rating, designed to operate at any one 
of three frequencies: 60, 120 or 240 
cycles/sec at approximately 115, 230 or 
460 v, giving speeds of 1800, 3600 and 
7200 rpm, respectively. This operation 
will provide film rates of 16, 32 or 64 
frames/sec. This selection of frame 
rates is available to the operator by 
means of a switch. 

The second type of motor is a conven- 



tional single-frequency (60 cycles/sec) 
single-speed, 110-v a-c synchronous, 
hysteresis type, 1800-rpm 1/20-hp rat- 
ing. It can be operated through gear- 
boxes, which must be changed before 
operation, to provide film rates of 16, 32 
or 64 frames/sec. 

The set of curves in Fig. 6 shows the 
various horsepower requirements at 
different frame speeds at normal tem- 
peratures. Laboratory tests were made 
with Mitchell high-speed movements at 
the three different frame rates both at 
normal and cold temperatures to deter- 
mine the required torque output from a 
synchronous motor. Both old and new 
film movements were used. Figure 7 
shows a typical curve of temperature 
affecting camera power requirements. 



42 



July 1953 Journal of the SMPTE Vol. 61 



n n n n n n n n 




N 


FRAME 
COUNTER 


7 

EL DIAL 








ro 


\ 


O) 




AZ DIAL 




00 


oe 0* OB ot 

FcTO 


Of 00 Ofr OC 
0*1 

-' (Jj 





7 



05 Ofr OB 

T 

6 01 01 oc 



) U U U U D U LTLJ 



Fig. 10. 35mm frame presentation. 



It is noted that from approximately 50 F 
upwards, the torque requirements are 
essentially the same, whereas around F 
the torque requirements are approxi- 
mately doubled. These results show at 
normal temperatures, approximately 
1/200 hp for 16 frames/sec, 1/100 hp for 
32 frames/sec, and 1/20 hp for 64 
frames/sec. A value of 1/15 hp was 
assumed to be a normally desirable 
capacity; the actual motor may prove 
to be closer to 1/8 hp. 

The motor may be brought to its high- 
est operating speed gradually by either 
the use of a variable-frequency input to 
the motor amplifier or by going through 
the lower discreet frame rates first. 
When synchronous speed is reached, the 
frequency input to the motor amplifier 
comes from a frequency standard. 

Figure 8 is a front-elevation view of 



the camera drum. A counter is located 
in the motor compartment and is geared 
to the- camera mechanism to show suc- 
cessive frame counts. A gaseous dis- 
charge tube illuminates this counter 
which serves as an object for a lens-and- 
prism arrangement which produces an 
image on the film. One leaf of the ad- 
justable shutter has a small slug of perme- 
able iron mounted on it. An electro- 
magnet is mounted on the camera body 
so that the outside edge of its core is close 
to the rotating shutter slug, producing a 
pulse which, when fed into a trigger am- 
plifier, flashes the Edgerton lamps in the 
instrument; one lamp is located at the 
azimuth dial, one at the elevation dial 
and the other at the frame counter. The 
pickup coil is located so that the rotating 
slug will produce a signal when the cen- 
ter of the shutter opening is at the center 



Lipton and Saffer: BRL-NGF Cinetheodolite 



43 



of the film-frame opening. When the 
shutter opening is changed, a variable 
resistance is set to produce enough pulse 
delay so that it still represents the center 
of the shutter opening at the center of the 
film frame. The instrument circuit is 
also designed to cause the Edgerton 
lamps to be flashed from external central 
timing pulses. The pulses from the shut- 
ter pickup are compared to the central 
timing pulses selected by the operator at 
16, 32 or 64 frames/sec on a small dual 
tube oscilloscope located on the pedestal 
of the instrument; the motor frame is 
then moved until the pulses coincide in 
phase. The film is receiving central 
timing pulses as light pips which appear 
as 100 pulses/sec and coded elapsed time 
every second. Therefore, film records 
from all similar instrumentation on the 
same range may be easily compared to- 
gether for the same time interval. A fil- 
ter wheel containing four Wratten Series 
VI filters is located close by and in front 
of the film-frame aperture. 

Figure 9 shows the prototype main 
optical tube and camera drum when the 
first unit was being constructed. 

Figure 10 shows the film frame presen- 
tation, with azimuth, elevation and 
frame-counter dials and fiducial marks. 



Discussion 

Wa/ter Beyer (Paramount Studios): In con- 
nection with the Mitchell movement I 
would like to know whether you replaced 
the shutter with another type? 

Mr. Lipton: We are not using the Venetian 
blind shutter. We are using the rotating, 
variable open type exactly as used on the 
Mitchell movement. 

Mr. Beyer: I also want to mention that I 
spent 15 years in Germany with the com- 
pany that manufactured these cinetheodo- 
lites, and I want to congratulate you on the 
improvements you have made. 



Mr. Lipton: Thank you. 

Mrs. Amy E. Griffin (Naval Ordnance Test 
Station}'. Have you given much thought to 
the problem of synchronizing the camera? 

Mr. Lipton: I believe I mentioned that 
we are going to use synchronization in this 
system. The central time station will 
generate pulses at the frame rate at which 
the camera will be used. For example, 
they will generate 64 pulses per second to 
each field station. These will feed into a 
divider from which the operator will select 
16, 32 or 64 pulses per second, correspond- 
ing to the frame rate at which he will oper- 
ate the camera. 

Mrs. Griffin: Do you have enough ex- 
perience with these lenses to know how long 
they will stay in focus because of tempera- 
ture conditions? 

Mr. Lipton: We've had quite a bit of ex- 
perience. What we normally do is check 
each day before shooting to make sure they 
are in focus. If we have a particular 
object distance and are intending to use the 
instrument for that, we have a calibration 
chart to show how much to move the secon- 
dary mirror for that particular object. 
For a short period of time, for example an 
hour, the focus will not change and, by the 
method we have outlined, it should be 
relatively simple for the operator to deter- 
mine first the infinity focus position, be- 
cause of the current temperature and light 
conditions, and then by the use of the pre- 
calculated chart, for example, move the 
secondary mirror the required amount for 
the object distance. I think this type of 
system has been used in the field, not pre- 
cisely in the way I have described it, but 
by the same general philosophy of adjust- 
ment. 

Mrs. Griffin: The reason I am interested 
is because we have used Gassegrainian lenses 
and then practically stopped using them 
because we couldn't keep them in focus 
long enough. I think the secondary 
mirror needs to have a very stable mount 
and one which will not vibrate and shake 
with the instrument as it is being used. 
We have pretty good luck with all refrac- 
tion-type lenses. 



44 



July 1953 Journal of the SMPTE Vol. 61 



16mm Projector for Full-Storage Operation 
With an Iconoscope Television Camera 



By EDWIN C. FRITTS 



A heavy-duty 16mm projector was described in 1950 by the author. 1 This 
projector has since been modified to adapt it to full-storage operation with a 
television camera. The modifications include a somewhat faster pulldown 
operating at the uniform rate of 24 frames/sec and a relay condenser system 
which, in combination with a special shutter and filters, provides adequate 
illumination of improved quality within blanking time. Operational facilities 
are also described. The accommodation problem of converting 24 frames/sec 
of motion pictures into 30 frames/sec for television is treated in an Appendix 
to the paper. 



A 



PROJECTOR for presenting motion 
pictures on a screen illuminates the 
screen for as long a period as possible 
while allowing the minimum of time for 
film advancement. In full-storage op- 
eration with an iconoscope in a 
television camera the procedure is 
reversed. The film is illuminated for 
only the brief period of vertical blank- 
ing, when no image is seen, and the 
image is stored as an electrostatic charge 
on the mosaic. The mosaic is dark as 
it is scanned. Thus, the greater time 
of the scanning intervals is available for 
the advancement of the film. However, 
an element of incompatibility exists 
between the 24 frames/sec of motion 



Presented on May 1, 1951, at the 
Society's Convention at New York, N. Y. 
by E. C. Fritts, Camera Works, Eastman 
Kodak Company, Rochester, N. Y. 
(Revised manuscript received on June 8, 
1953.) 



pictures and the 30 frames/sec of 
television which can be met in either of 
two ways. By changing the phase of 
alternate pulldown actions, they can 
all be made to center on the television 
fields in the so-called 2-3-2 sequence, 
and the length of pulldown can fill the 
greater part of a field. Or, if the pull- 
down is made shorter than one-half a 
field, by an amount sufficient to take 
care of all the necessary tolerances, the 
uniform 24-frames/sec sequence can be 
fitted between the blanking intervals 
(see Appendix). 

The projector to be discussed is a 
modification of the Eastman 16mm 
Projector, Model 25, which the author 
has previously described. 1 Let us con- 
sider first the basic modifications of this 
projector to meet the functional re- 
quirements as applied to its use in 
television. Then we will discuss the 
operational problems and, without too 
much detail, the means of meeting them. 



July 1953 Journal of the SMPTE Vol. 61 



45 



Fundamental Principles 

These include: (1) a pulldown to 
operate at the uniform rate of 24 frames/- 
sec and yet dodge the vertical blanking 
intervals, (2) the unique problem of the 
shutter and optical system as described, 

(3) the proper quality of the light for 
best response from the iconoscope and 

(4) a modification of the projection 
objective to work at a 1. to 12 magni- 
fication. 

The Pulldown. This projector makes 
use of the shorter pulldown operating 
at the uniform rate of 24 frames/sec. 
Certain tolerances are necessary in the 
accommodation of this pulldown within 
the scanning time, or, more exactly, 
to dodge the transmission time of the 
shutter, which itself is contained within 
the blanking interval. These include 
phasing tolerance, tolerance in the 
adjustment of the pulldown to the 
shutter at the time of installation, and 
an allowance for framing, since framing 
alters the position of the pulldown with 
respect to the shutter. Reference is 
made in the original paper to the tuning 
of the coupling system between the 
intermittent and its individual motor. 
This tuning is adjusted, in the case of 
the television projector, to reduce the 
time of pulldown action to the required 
value. 

The Shutter and Optical Systems. These 
items are considered together because 
of the unique problem inherent in such 
a projector. The angle of the shutter 
necessary to occult the optical system 
is always to be considered in the design 
of a shutter and optical system. The 
problem is unique in this case because 
of the very short time available for 
exposure. Should a shutter of the proper 
speed of 60 rps be placed in the position 
ordinarily used, that is immediately 
behind the gate, the occulting angle 
would equal approximately the total 



available angle of transmission and leave 
little or no angle for an opening in the 
shutter. 

To meet this condition, we must 
reduce the diameter of the cross section 
of the light beam or use a larger shutter, 
or both. The use of a relay optical 
system makes it possible to contain the 
light in a small aerial image of the 
filament. This image is also formed to 
the rear of the mechanism, in the normal 
position for the lamp filament, which 
provides clearance for a large shutter. 
Thus, the efficiency of the shutter is 
raised to where sufficient illumination is 
obtained from a 1000-w, 10-hr lamp. 

Grimwood and Veal 2 have found that 
the response characteristics of the icono- 
scope are improved if the quality of the 
radiation from a tungsten source is 
altered, particularly to remove a portion 
of the spectrum in the red and infrared. 
Filters are placed in the optical system 
for this purpose. 

The projection lens must image the 
film at a 1 to 12 magnification. The 
lenses used in the Model 25 were de- 
scribed by Schade. 3 A 4-in. lens of this 
design is fitted with a compensator 
which essentially permits the basic 
objective to occupy the exact position 
it would be in when projecting onto a 
distant screen without the compensa- 
tion. Thus the excellent corrections 
are preserved. 

Operational Conditions 

We now consider those features of the 
projector which pertain specifically to 
the problem of manipulation. These 
include: (1) arrangement of parts to 
fit into a multiplexing combination of 
more than one projector for one tele- 
vision camera, (2) the separate shutter 
motor, (3) controls for remote operation, 
(4) controls to assure proper phasing 
of shutter to vertical blanking and of 
the pulldown to the shutter, (5) still- 
picture operation and (6) the special 
preamplifier. 



July 1953 Journal of the SMPTE Vol. 61 



Arrangement of Parts. A mirror is 
generally placed between the projection 
objective and the iconoscope for multi- 
plexing, and the mounting of this mirror 
comes close to the front of the projector. 
Hence it is necessary to move the film 
reels backwards from their position on 
the Model 25, as will be seen in Fig. 1. 
The 4-in. lens is used to provide an 
optical system of sufficient length for 
the necessary clearance. 

Separate Shutter Motor. The separation 
of the mechanism of the Model 25 
Projector into two completely inde- 
pendent units with separate synchro- 
nous motors is the main reason for the 
low noise and flutter and long life of 
the mechanism. For the same reasons 
the shutter of the television modi- 
fication is driven by a separate three- 
phase synchronous motor running at 
3600 rpm. The greater speed and larger 
moment of inertia of this shutter and 
the requirement for greater stability 
have determined the choice of the three- 
phase operation and the generous size 
of the motor. When synchronous motors 
are linked to large moments of inertia, 
as is the case with this shutter, the 
limiting factor in the size of the motor 
is its capacity to pull the shutter mass 
into synchronism. A three-phase motor 
permits starting without an internal 
switch and is more stable in operation 
than a single-phase motor. 

An additional and equally important 
reason for the separate shutter motor is 
to shorten the starting and stopping 
wastage of film by letting the heavy 
shutter system coast to a stop inde- 
pendent of the mechanism which stops 
much more rapidly. The time of 
starting is short because the large torque 
required for the "pull into synchronism" 
is available for greater acceleration in 
starting. 

Controls. The requirement of remote 
operation calls for a more complicated 
switching system including a number of 




Fig. 1. The Eastman 16mm Television 
Projector Model 250 



Edwin C. Fritts: Television Projector 



47 



relays. This will not be described in 
detail. It provides for a rather flexible 
adjustment to studio conditions, for 
operation from the projector and the 
monitor positions and includes a douser 
and provision for still pictures. 

Phasing. Two elements of phasing 
are involved: (1) the shutter opening 
must occur at the vertical blanking 
time and (2) the pulldown must dodge 
this open time. 

The motors are all of the salient pole 
type. Because of the two possible 
magnetic polarities on the poles of the 
rotors, they can occupy either of two 
positions in rotation with respect to the 
waveform of the power supply, 180 
electrical degrees apart. For the two- 
pole shutter motor, this separation 
represents 180 mechanical degrees, while 
the four-pole mechanism motor shifts 
90 degrees and the pulldown motor 
shifts 72 degrees, if the polarity is re- 
versed. Once the pulldown is adjusted 
to miss the shutter openings, the reversal 
of polarity in the mechanism motors is 
of no consequence when the short pull- 
down is used. With the longer 2-3-2 
action these motors would need to be 
phased at each starting. This problem 
is treated in more detail in the Appendix. 

The shutter opening must occur at 
the time of vertical blanking. Accord- 
ingly, on installation, it must be adjusted 
in rotation with respect to the motor 
rotor until this is true. In operation, 
the choice of polarity of the rotor is 
necessary to have the exposure occur 
properly during blanking time rather 
than as a "shutter bar" in the middle 
of scanning. This choice is made each 
time the motor starts. The intelligence 
for this choice is a half-wave rectified 
power supply. A commutator on the 
motor shaft closes two contacting brushes 
once per revolution. This contact 
occurs either at the peak of the half- 
wave voltage or midway in the blocking 
period of the rectifier when no voltage 
occurs. In the former case, a pulse of 



current closes a relay which momen- 
tarily opens the motor circuit, causing 
it to slip a pole. Then the contact 
will occur at the time of no voltage, 
and the phasing is correct. When the 
"On" button is pressed, a motor-driven 
switch operates through a 4-sec sequence 
which actuates a solenoid to bring the 
brushes into momentary contact and 
then removes them. Phasing is accom- 
plished during this time. This same 
switch changes the lamp from a standby 
low voltage to operational voltage. 
The resulting slow switching of the lamp 
has much to do with contact life of the 
switch. Pressing the "Off" button ro- 
tates the switch to the off position. 

Still-Picture Projection. Another advan- 
. tage of a separate shutter motor is in 
the projection of a single frame. Since 
most of the infrared is removed from 
the radiation by filters, a single frame 
can be projected indefinitely. While 
the shutter is running, the lamp can be 
operated at normal voltage, and the 
projector may be interchanged between 
still and motion projection by merely 
starting and stopping the mechanism. 

Preamplifier. The photoelectric cell 
feeds into a special preamplifier with 
a maximum output of 14 dbm. The 
equalization curves are shown in Fig. 2. 
The output transformer has a choice of 
impedance of 75, 150, 300 or 600 ohm. 

This projector known as the Eastman 
16mm Television Projector Model 250 
is designed, as is the Model 25, for long 
life, high-quality operation and low 
noise, both mechanical and electrical. 
The control system, while of necessity 
more complicated than in the Model 25, 
is easily accessible for servicing. 
Troublesome elements are avoided 
throughout as far as possible, par- 
ticularly where they might not be 
readily accessible. The absence of 
enclosed starting switches in the motors 
is such a case. Also, the shutter motor 



48 



July 1953 Journal of the SMPTE Vol. 61 



10 



-15 



I I 




I I 



I I 



50 100 500 IK 5K 10K 

FREQUENCY IN CYCLES PER SECOND 
Fig. 2. The audio-response characteristics of the projector. 




Fig. 3. Rear view of exposed mechanism. 
Edwin C. Fritts: Television Projector 



49 



has no winding on the rotor. This 
avoids a d-c power supply, the collector 
ring and the winding itself. A failure 
of any of these would disable the motor. 
Rather, the phasing mechanism is all 
external to the motor, simple, and 
easily accessible for servicing. Figure 1 
shows the general view of the projector. 
Fig. 3 shows the rear view with case 
removed. 



References 

1. E. C. Fritts, "A heavy-duty 16mm 
sound projector," Jour. SMPTE, 55: 
425-438, Oct. 1950. 

2. T. G. Veal and W. K. Grimwood, "Use 
of color filter in a television film camera 
chain," Jour. SMPTE, 57: 259-266, 
Sept. 1951. 

3. W. E. Schade, "A new //1. 5 lens for 
professional 16mm projectors," Jour. 
SMPTE, 54: 337-344, Mar. 1950. 



APPENDIX 



The accommodation of 24 frames/sec 
for motion pictures to 30 frames, 60 
fields/sec for television presents a difficult 
problem in the application of motion 
pictures to television. Less than 1 
msec is available for film movement if 
the conventional motion-picture practice 
is followed of advancing the film when 
no picture information is presented. 
Such a rapid pulldown would involve, 
as a general observation, fifty times the 
magnitude of forces as occur in a 60 
pulldown used in motion-picture pro- 
jection. 

In projecting into an iconoscope of a 
television camera, a dodge of this 
problem is followed. The exposure is 
made when picture information is not 
presented, that is, during vertical blank- 
ing time. The iconoscope will remember 
the exposure as an electrostatic image 
which is removed during scanning to 
produce the picture signal. Thus, we 
have the whole scanning time in which 
to advance the film. This time is quite 
ample except for the 24-frame and 30- 
frame relationship. 

Let us consider this relationship. 
The greatest common denominator of 
1/24 and 1/30 is 1/120. 1/120 sec is 
equivalent to half a television field. 
1/24 sec is equivalent to 5/2 a television 
field, 1/30 sec is equivalent to 4/2 a 
television field, and 20 half-fields is the 
minimum number to contain an integral 
number of both motion-picture frames 
and television frames. 




Fig. 4. Motion-picture and television 
relationship. 

Figure 4 shows a circular chart of ten 
fields. Since half-fields are a common 
denominator in this scheme of things, a 
pulldown which takes place in less than 
a half-field, or 1/120 sec, and at a regular 
interval of 1/24 sec, can be so phased on 
our chart as always to miss the blanking 
time when the exposure is made. The 
four outermost and smaller boxed seg- 
ments on our chart represent such a 
placement of pulldown actions. The 
larger outlined segments represent a so- 
called 2-3-2 pulldown sequence. This 
sequence, it will be seen, is alternately 
spaced by two fields and three fields. 
Either sequence misses the blanking 
times. Thus motion pictures can be 



50 



July 1953 Journal of the SMPTE Vol. 61 



projected into television on a storage 
basis at the uniform rate of 24 frames/sec 
if the pulldown actions occupy less than 
half a field. Or, the lengths of pulld\\ n 
may be approximately twice this length 
if alternate actions are spaced by two and 
three television fields, that is by 2/60 
sec and 3/60 sec. The average of 
2/60 and 3/60 equals 1/24. 

We should also observe a difference 
between these two types of action when 
the phase of either is shifted one-half a 
field with respect to the blanking-time 



sequence. Such a shift is the result of a 
reversal of polarity in the rotor of a 
synchronous motor. In the case of the 
shorter regular sequent e. ihev will 
always miss while the longer 2-3-2 
sequence will fall astride the blanking 
times if the phase is shifted one-half 
field from that shown in the chart. 

Thus the 2-3-2 sequence requires 
that the polarity of the motor driving 
the pulldown be always the same, while 
this is of no significance with the shorter 
and uniform 24-cycle sequence. 



Errata 

George R. Groves, "Progress Committee Report," Jour. SMPTE, 60: 535-552, May 
1953. 

In preparing final proofs, under the subheading "Film Processing Laboratories," a regret- 
table wrong transposition and error were perpetrated. The fifth and sixth paragraphs of 
that section should have begun with the following information, respectively: 

Consolidated Film Industries constructed a new laboratory building to be used exclusively 
for 16mm processing and printing . . . ." 

"General Film Laboratories was a new entry into the independent laboratory field, having 
taken over the former Paramount facility. ..." 



Edwin C. Fritts: Television Projector 



51 



1953 (Issue No. 2) SMPTE Television Test Film: 

Operating Instructions 



PURPOSE 

THE Television Test Film is intended to 
provide a means by which performance 
tests of a television film reproduction 
system can be made on a routine opera- 
tional basis. Its test sections are chosen 
to emphasize errors of physical align- 
ment and electrical adjustment in such a 
way that needed corrections become ap- 
parent. It is suggested that the reel be 
run through all projection equipment at 
regular intervals to provide a standard- 
ized indication of normal operation. In 
this way equipment malfunction may be 
detected before its effect becomes serious. 
This film is not intended to be a labo- 
ratory instrument, although it may be 
useful in product designing and testing. 

CONTENTS 

Six test sections and a selection of 
scenes comprise the complete film, 
which is available in either 16mm or 
35mm widths. The test sections are 
geometrical patterns intended to present 
information on the factors most likely 



to be degraded in television film re- 
production. Each chart selects some 
particular failing of the average system 
and produces a signal intended to 
exaggerate and thus clearly define any 
deviation from normal operation. Per- 
fect reproduction of all the charts is to 
be desired, but some degradation of each 
is to be expected. Experience will show 
the magnitude of these effects which 
may be considered normal for any 
particular system. 

Scenes representative of many types 
of pictures encountered in television 
films are included in the reel as a final 
qualitative test of overall results. 

Sec. 1. Alignment and Resolution 
(See Fig. 1) 

This pattern defines the portion of the 
projected film frame which is to be 
reproduced by the television system, 
permitting accurate alignment of the 
motion-picture projector with the tele- 
vision camera. Eight arrow points 
have been positioned to touch the edges 
of the picture area to be scanned. This 



On January 23, 1953, a meeting of the Films for Television Committee was called by 
Dr. Raymond L. Garman, Chairman, for the purpose of reaching a decision on a number 
of changes in the television test film which had been under consideration for some time. 

Agreement was reached on changes modernizing the main title, changes in the wording 
of some section target titles, changes in length of revised sections, elimination of the 
1-3-1 step gray-scale target and lengthening the section showing the target with two 
seven-step tablets. 

It was agreed to accept the compromise proposal on picture size for use in setting the 
dimensions of the alignment target at the arrow points. This means that for 35mm, the 
reproduced dimensions will be 0.594 0.002 X 0.792 d= 0.002 in. which, when reduced 
by the standard ratio of 2.15, will give a 16mm size of 0.276 0.002 X 0.368 d= 0.002 in. 

Charles L. Townsend presented a new target, combining the alignment and resolution 
tests, which after careful consideration was approved. The committee gratefully ex- 
tended its thanks to Mr. Townsend and NBC for their excellent work in preparing this 
target and for their generosity in making it available to the Society without charge. 

These changes have been made in the film, and the operating instructions (originally 
published in the Journal in February 1950, pp. 209-218) revised accordingly. 



July 1953 Journal of the SMPTE Vol. 61 




Figure 1 



"active area" conforms with a proposed 
standard developed by a joint RTMA/ 
SMPTE committee representing the 
industry as a whole. It is intended to 
be used by producers of films for tele- 
vision as well as broadcasting stations 
to insure accurate scene-content re- 
production. The area outside the arrow 
points has been striped with a "barber- 
pole" effect which extends to the limit 
of the printer aperture. When the 
projector is positioned correctly and 
scanning is adjusted perfectly all the 
picture frame to the arrow tips will be 
reproduced on the television system, but 
none of the striped area will show. 

It should be noted that the striped 
area is wider on the sides of the frame 
than on the top and bottom. This 
results from the fact that the standard 
projection aperture does not have a four- 
to-three ratio but is wider by some 3% 
(see the American Standards for Picture 
Projection Apertures, Z22.58-1947 and 
Z22.8-1950). It may be necessary in 
some 35mm projectors to enlarge the 
projection aperture vertically to show 



some barber-pole across both the top 
and the bottom of the picture. This is 
advisable to allow for small scanning 
irregularities and centering drifts with- 
out loss of active picture area. When 
such irregularities are encountered, size 
and centering controls should be ad- 
justed to reproduce as much of the 
"active area" as possible even though 
some barber-pole may be reproduced. 
Experience will dictate what compromise 
settings are required by opposing drift 
and picture-loss considerations. 

At the base of the arrow heads is a 
white line forming a rectangle which 
defines a 5% border around the active 
area. That is, the lines at the top and 
bottom are placed in from the edges by 
5% of the height, and the lines at the 
sides are placed in from the edges by 
5% of the width. These dimensions 
permit rough estimates of the magnitude 
of scanning irregularity or misalignment 
through visual comparison of the effecte 
in question with the size of the border. 
Specific values for misalignment ob- 
tained in this manner can be logged 



1953 (Issue No. 2) SMPTE Television Test Film 



53 




Figure 2 



easily for future reference as part of a 
quality-control program. 

White lines are provided in the center 
of each edge, and a cross is located in 
the exact center of the pattern to aid in 
alignment of the optical pattern on the 
pickup-tube plate. 

A gross estimate of scanning-dis- 
tribution errors can be obtained by 
observing the "roundness" of the large 
circle. Localized errors will show up 
as deformations of the small central 
circles or those in the corners of the 
pattern. Observations of this sort 
require a carefully calibrated picture 
monitor to insure that all defects noted 
are in the film-scanning system and not 
in the picture monitor. It should be 
noted that the arrows are equally spaced 
with respect to the corners and center 
lines. When scanning defects are noted, 
a ruler laid along the calibrated monitor 
picture will indicate the place and size 
of the scanning error. 

Overall system resolution is indicated 
by the converging line wedges in the 
pattern. By noting the point at which 



the individual lines making up the 
wedges are no longer visible separately, 
an estimate of the value of system 
resolution can be made from the cali- 
bration adjacent to that point. The 
calibrations are in television system 
lines. The small corner wedges are 
marked in hundreds of television lines. 
These wedges may be used for checks of 
both optical and electrical focus. 

Sec. 2. Low-Frequency Response 
(See Fig. 2) 

This test is made in two parts, each 
consisting of a half-black/half-white 
frame, with the dividing line horizontal. 
The first section has the black portion 
at the top of the frame and the second is 
black at the bottom. These charts 
produce 60-cycle square-wave signals. 
When viewed on the waveform monitor 
set for field-rate deflection, the signals 
should appear reasonably square. Seri- 
ous tilting or bowing indicates incorrect 
low-frequency phase and amplitude 
response. When the system has been 
set for reproducing the first chart, the 



54 



July 1953 Journal of the SMPTE Vol. 61 




Figure 3 



change to the second chart should not 
necessitate large shading changes. 

The chart which is black at the bottom 
also permits a check on the amount of 
flare encountered in iconoscope opera- 
tion. Rim lights and beam current 
should be reset if the flare is excessive. 

Sec. 3. Medium-Frequency Response 
(See Fig. 3) 

The response of the television system 
to medium-frequency signals is of im- 
portance to picture quality. In this 
test, horizontal bars are used, first as 
black on white and then reversed. The 
bars have lengths equal in time of scan- 
ning-beam travel to 2, 5, 1 2\ and 32 mi- 
croseconds. These correspond to half- 
wave pulses covering an approximate 
fundamental frequency range from 15 to 
250 kilocycles. Correct medium-fre- 
quency phase and amplitude response will 
be indicated by leading and trailing edges 
of the bars having no long, false gray tones. 
If, following the trailing edge of a bar, a 
streak appears having a tone similar to 
that of the bar (white after white, black 



after black), then it is reasonable to 
assume that the amplitude of the fre- 
quency represented by that bar is too 
great, or that its relative phase is in- 
correct. If the opposite occurs, as a 
white streak after a black bar, the 
fundamental frequency is too low in 
amplitude, and its relative phase is in 
error. 

Sharp transient effects immediately 
following all bars are an indication of 
excessive high-frequency response. This 
condition will usually be clearly in- 
dicated in the test for resolution. 

If very long streaking occurs in which 
the spurious signals are seen on the left 
side of the bars, as well as on the right, 
an investigation of the low-frequency 
response of the system should be made. 
Under these conditions close examination 
of the previous charts should reveal 
errors of waveform. 

It is rarely possible to obtain perfect 
streaking-free reproductions of both the 
black-on-white and the white-on-black 
charts with one setting of the controls. 
The settings which produce very small 



1953 (Issue No. 2) SMPTE Television Test Film 



55 




Figure 4 



streaking equally on both charts are 
usually preferred. 

Sec. 4. Storage (See Fig. 4) 

Film pickup systems which utilize 
short pulses of light must store the 
charge produced by the pulse long 
enough to permit the charge image to 
be scanned. Since the beam starts the 
scanning process at the top of the 
picture, the storage time required is 
maximum at the bottom of the picture. 
Some pickup tubes will suffer from 
leakage to the extent that the charge 
image may be seriously reduced in 
amplitude by the time the beam reaches 
the bottom of the picture. 

The chart which checks this charac- 
teristic is made up of vertical black and 
white stripes on a gray background. 
When viewed on the waveform monitor 
(set at field rate) this pattern will 
produce three lines representing white, 
gray and black. Shading should be 
set to hold the gray line parallel with the 
blanking axis. If the white and black 
lines then tend to converge, the pickup 



tube does not have perfect storage. 
Perfect results are indicated when all 
traces are parallel. If the black-to- 
white amplitude at the bottom of the 
picture is divided by that at the top 
of the picture, the tube's storage factor 
is obtained. This is usually expressed in 
percentage. 

Sec. 5. Transfer Characteristics 
(See Fig. 5) 

The ability of a television system to 
reproduce shades of gray is indicated 
in this section through the use of step- 
density areas. The chart consists of 
two step-density tablets showing seven 
steps each. The direction of pro- 
gression of the second tablet is opposite 
to that of the first to provide maximum 
values at each side of the picture frame. 

The neutral gray background of this 
chart should be shaded flat, and gain 
and brightness settings should be ad- 
justed to give normal waveform-monitor 
amplitudes. Under these conditions 
each step should be visually compared 
with the adjacent steps, both in the 



56 



July 1953 Journal of the SMPTE Vol. 61 




Figure 5 




Figure 6 
1953 (Issue No. 2) SMPTE Television Test Film 



57 




Figure 7 



picture and on the waveform monitor, 
and each should be clearly defined. 
Compression effects will be seen as a 
cramping together of adjacent steps. 
Experience as to the appearance of the 
tablets will establish a norm from which 
variations can be noted. 

The effective transfer characteristic 
of a film-pickup system is a function of 
both film density and projected illumi- 
nation. This test film has a range 
considered to represent that normally 
encountered in practice. If significant 
compression occurs, projector bright- 
ness should be checked. Other factors, 
including beam current, bias-light, and 
clipper adjustments should be tested with 
a stationary slide. 

Sec. 6. Automatic Brightness Control 
(See Fig. 6) 

This test indicates the ability of the 
television system to follow changes in 
average illumination of a series of scenes. 
It consists of a white disk centered in a 
black frame which enlarges slowly to 
fill the whole frame. As the white por- 



tion becomes larger, the brightness 
control should hold the black level 
constant. On the waveform monitor, 
the black signals should remain fixed, 
in position relative to the blanking level. 
The first brightness changes on the film 
are both slow and even, so that systems 
with slow-acting control should be able 
to follow them accurately. 

The second portion of the test consists 
of sudden changes in white disk size from 
the smallest size to one third of the 
frame area and then to two thirds of 
the frame area. Experience will show 
how much error in black-level setting 
results in these cases on a transient basis. 

Sec. 7. Typical Scenes (See Fig. 7) 

To provide a qualitative check on the 
overall results to be expected from 
good film, several scenes taken from 
material used specifically for television 
are included in the test reel. Utiliza- 
tion of this section will depend upon the 
operator's experience in judging ac- 
ceptability and upon his memory of 
"how they looked before." 



58 



July 1953 Journal of the SMPTE Vol. 61 



Two Proposed American Standards PH22.95, 
PH22.96 

Television Picture Area 35mm and 16mm 
Motion-Picture Film 

Two PROPOSED American Standards on 35mm and 16mm television picture area 
are published on the following pages for 3-month trial and criticism. All comments 
should be sent to Henry Kogel, Staff Engineer, prior to November 1, 1953. If no 
adverse comments are received, the proposals will then be submitted to ASA Sec- 
tional Committee PH22 for further processing as American Standards. 

The two proposals are consistent with existing standards for camera and projector 
apertures, with one exception. The standard 35mm projector aperture was con- 
sidered unsatisfactory for television use because its aspect ratio is not 4 by 3 and be- 
cause its specified height results in a loss of picture area that was considered by many 
to be excessive. The present proposal increases the height of the 35mm projector 
aperture as much as possible without requiring enlargement of the 1 6mm projector 
aperture, thus permitting reproduction of optical reduction prints. Enlargement of 
the 35mm aperture is considered permissible because the number of 35mm projectors 
now in television use is not great and because the construction of 35mm equipment 
makes alteration or replacement of the aperture a very simple matter. F. N. Gil- 
lette, Chairman, Television Film Equipment Committee. 



July 1953 Journal of the SMPTE Vol. 61 59 



Proposed American Standard 

Television Picture Area- 
35mm Motion-Picture Film 

(Third Draft) 



PH22.95 



Page 1 of 2 pages 



1. Scope 

1.1 The area to be included in a television 
picture is determined at the point of origina- 
tion of the program concerned. In subsequent 
treatment of the resulting picture, it is very 
important that excessive cropping of the 
edges of the picture be avoided. The purpose 
of this Standard is to establish operat- 
ing procedures which will minimize the loss 
in area sustained in recording a television 
picture on 35mm film and in subsequently re- 
producing the film with a television film chain, 
and also to prevent the televising of a black 
or white band formed by the edge of the re- 
corded area or the projector aperture. 

1.2 Since the film chain equipment will also 
be used, without intervening readjustment of 
the equipment, for reproduction of films pro- 
duced by standard photographic techniques, 
the Standard provides for optimum utiliza- 
tion of the picture area of standard 35mm 
motion-picture film. 

1.3 Film prepared by conventional photo- 
graphic techniques for television reproduc- 
tion shall be prepared in accord with the 
provisions of Z22.59-1947, Photographing 
Aperture of 35mm Sound Motion Picture Cam- 
eras, or the latest revision thereof, approved 
by the American Standards Association, In- 
corporated, which specifies the location and 
size of the camera aperture. The loss of sig- 
nificant picture information in television re- 
production can be avoided by providing in 



the camera viewfinder an indication of the 
area to be scanned in television reproduction. 

1.4 Paragraph 2 of this Standard applies 
only to video recordings intended for repro- 
duction by a television system. If the video 
recording is intended for direct projection to 
a theater screen the image dimensions, with 
the exception of picture width, are adequately 
specified by American Standard Z22.59- 
1947, or the latest revision thereof. For the 
correct aspect ratio the image width should 
be 0.841 0.004 inch. 

2. Video Recording on 35mm 
Motion-Picture Film 

2.1 The picture aperture of a 35mm tele- 
vision recording camera shall be in accord 
with American Standard Z22.59-1947, or the 
latest revision thereof. 

2.2 The television picture appearing on the 
picture tube of the video recording equipment 
shall produce an image on the recording film 
having a height of 0.612 =fc 0.004 inch and 
a width of 0.816 0.004 inch. 

2.3 The center point of the image shall co- 
incide with the center point of the picture 
aperture of a 35mm motion-picture projector 
as specified by American Standard Z22.58- 
1947, Picture Projection Aperture of 35mm 
Sound Motion Picture Projectors, or the latest 
revision thereof, approved by the American 



NOT APPROVED 



60 



July 1953 Journal of the SMPTE Vol. 61 



Page 2 of 3 pag> 



Standards Association, Incorporated. (This ac- 
tually serves to locate the image relative to 
the film.) 

3. Television Reproduction of 35mm 
Motion-Picture Film 

3.1 Except for height and width dimensions 
the picture aperture of a 35mm television pro- 
jector shall be in accord with American Stand- 
ard Z22.58-1947, or the latest revision 
thereof. The height dimension shall be 
0.612 0.002 inch and the width dimension 
shall be 0.81 6 =t 0.002 inch. 



3.2 The portion of a 35mm motion-picture 
film reproduced by a television film chain 
shall be an area having a height of 0.594 =*= 
0.004 inch and a width of 0.792 : 0.004 
inch. 

3.3 The center point of the reproduced por- 
tion of the film shall coincide with the center 
point of the picture aperture of a 35mm mo- 
tion-picture projector as specified by Ameri- 
can Standard Z22.58-1947, or the latest re- 
vision thereof. (This actually serves to locate 
the reproduced area relative to the film.) 



NOT APPROVED 



PH22.95 



July 1953 Journal of the SMPTE Vol. 61 



Proposed American Standard 

Television Picture Area 
16mm Motion-Picture Film 

(Third Draft) 



PH22.96 



Page 1 of 2 pages 



1. Scope 

1.1 The area to be included in a television 
picture is determined at the point of origina- 
tion of the program concerned. In subsequent 
treatment of the resulting picture, it is very 
important that excessive cropping of the 
edges of the picture be avoided. The purpose 
of this Standard is to establish operat- 
ing procedures which will minimize the loss 
in area sustained in recording a television 
picture on 16mm film and in subsequently re- 
producing the film with a television film chain, 
and also to prevent the televising of a black 
or white band formed by the edge of the re- 
corded area or the projector aperture. 

1.2 Since the film chain equipment will also 
be used, without intervening readjustment of 
the equipment, for reproduction of films pro- 
duced by standard photographic techniques, 
the Standard provides for optimum utiliza- 
tion of the picture area of standard 16mm 
motion-picture film. 

1.3 Film prepared by conventional photo- 
graphic techniques for television reproduction 
shall be prepared in accord with the provi- 
sions of American Standard Z22.7-1950, Lo- 
cation and Size of Picture Aperture of 16mm 
Motion Picture Cameras, or the latest revision 
thereof, approved by the American Stand- 
ards Association, Incorporated, which speci- 
fies the location and size of the camera aper- 
ture. The loss of significant picture information 
in television reproduction can be avoided by 
providing in the camera viewfinder an indi- 
cation of the area to be scanned in television 
reproduction. 



1.4 Paragraph 2 of this Standard applies 
only to video recordings intended for repro- 
duction by a television system. If the video 
recording is intended for direct projection to 
a theater screen the image dimensions are 
adequately specified by American Standard 
Z22.7-1950, or the latest revision thereof. 

2. Video Recording on 16mm 
Motion-Picture Film 

2.1 The picture aperture of a 16mm tele- 
vision recording camera shall be in accord 
with American Standard Z22.7-1950, or the 
latest revision thereof. 

2.2 The television picture appearing on the 
picture tube of the video recording equipment 
shall produce an image on the recording film 
having a height of 0.285 =i= 0.002 inch and 
a width of 0.380 0.002 inch. 

2.3 The center point of the image shall coin- 
cide with the center point of the picture aper- 
ture of a 16mm motion-picture camera as 
specified by American Standard Z22.7-1950, 
or the latest revision thereof. (This actually 
serves to locate the image relative to the film.) 

3. Television Reproduction of 16mm 
Motion-Picture Film 

3.1 The picture aperture of a 16mm tele- 
vision projector shall be in accord with Ameri- 
can Standard Z22.8-1950, Location and Size 
of Picture Aperture of 16mm Motion Picture 
Projectors, or the latest revision thereof, ap- 
proved by the American Standards Associa- 
tion, Incorporated. 



NOT APPROVED 



62 



July 1953 Journal of the SMPTE Vol. 61 



3.2 The portion of a 16mm motion-picture tion of the film shall coincide with the center 
film reproduced by a television film chain point of the picture aperture of a 16mm mo- 
shall be an area having a height of 0.276 =t tion-picture projector as specified by Ameri- 
0.002 inch and a width of 0.368 0.002 can Standard Z22.8-1950, or the latest re- 
vision thereof. (This actually serves to locate 

3.3 The center point of the reproduced por- the reproduced area relative to the film.) 



NOT APPROVED PH22.96 



CORRECTION PH22.53-1953 

Method of Determining Resolving Power 
of 16mm Motion-Picture Projector Lenses 



THIS AMERICAN STANDARD, last published in the May 1953 Journal, is reprinted 
on the two following pages, with typographical corrections made in paragraph 2.1.1 
and in the first line of the Note directly under the title of Fig. 3. 



July 1953 Journal of the SMPTE Vol. 61 63 



AMERICAN STANDARD 

Method of Determining 

Resolving Power of 16mm Motion -Picture 

Projector Lenses 



Reg. V. S. Pat. Of. 

PH22.53-1953 



Revision of Z22.53-1944 
*UDC 778.55 



1. Scope 

1.1 This standard describes a method of de- 
termining the resolving power of projection 
lenses used in 16mm motion-picture projec- 
tors. The resolving power shall be measured 
in lines per millimeter. 

2. Test Method 

2.1 The lens to be tested shall be mounted in 
a special test projector. A glass plate test 
object, carrying patterns of lines, shall be 
then projected upon a white matte grainless 
screen located at such a distance from the 
projector that the projected image of the bor- 
der of the test object measures 30 X 40 
inches. The resolving power of the lens is the 
largest number of lines per millimeter in the 
test object pattern that an observer standing 
close to the screen sees definitely resolved in 
both the radial and tangential directions. 
Lines shall not be regarded as definitely re- 
solved unless the number of lines in the image 
is the same as the number of lines in the test 
object. 

2.1.1 The patterns of lines shall consist of 
parallel black lines 2.5/X mm long and 
0.5/X mm wide with a clear space 0.5/X mm 
wide between the parallel lines, where X 
equals the number of lines per millimeter. 

2.2 Care shall be taken to insure that the 
screen is perpendicular to the projection axis 
and that the lens is focused to give the maxi- 
mum visual contrast in the fine detail of the 
central image. 



Page 1 of 2 pages 



3. Test Projector 

3.1 The projector design shall be such that 
the glass plate test object is held in proper 
relation to the lens axis. It shall not heat the 
test plate to a temperature which may cause 
the plate to be fractured or otherwise dam- 
aged. The emulsion side of the test plate shall 
be toward the projection lens. 

3.1.1 The cone of light supplied by the pro- 
jector shall completely fill the unvignetted 
aperture of the test lens for all points in the 
field. This may be verified by lowering the 
lamp voltage and looking back into the pro- 
jection lens through holes in the projection 
screen situated at the stations A, B, C, etc. It 
can then be easily seen whether the lens aper- 
ture is properly filled with light. 

4. Test Object 

4.1 The glass photographic plate used for 
making the test object and the lens used in 
making the reduction of the master test chart 
shall have sufficiently high resolving power 
to insure clear definition of all lines in the 
patterns on the test object. 

4.2 The photographic reduction of the mas- 
ter test chart shall be such that the test object 
border has a height of 7.21 mm (0.284 inch) 
and a width of 9.65 mm (0.380 inch) with a 
radius of 0.5 mm (0.02 inch) in the corners, 
and such that the sets of lines in the reduced 
image are spaced 20, 30, 40, 50, 60, 80, 
and 90 lines per millimeter. 



Approved April 16, 1953, by the American Standards Association, Incorporated 
Sponsor: Society of Motion Picture and Television Engineers 



al Decimal Classification 



Copyright 1953 by the American Standards Association, Incorporated 
70 East Forty.fifth Street, New York 17. N. Y. 



Printed in U.S.A. 
ASA%M653 



Price, 25 Cents 



64 



July 1953 Journal of the SMPTE Vol. 61 



50MI5 ' 
40 i= '"=80 

30 1 11= -90 

HIE 

20 

Fig. 1. Resolution Test Patterns 
(X 100 Diameters). 



p. fl . a a 



4.3 The patterns on the test object shall be 
in accordance with Fig. 1. 

4.4 The position of the test patterns on the 
test object shall be in accordance with 
Fig. 2. 

4.5 Identification of the positions of the test 
patterns on the test object shall be in accor- 
dance with Fig. 3. 



Project to 40 Inches on White Matte Gramless Screen 




Fig. 2. Resolving Power Test Object (X Approximately 15 Diameters). 

Note: The triangular edge patterns are to facilitate alignment of test plates in the projector. 



Fig. 3. Identification of Test Patterns 
in Frame Area. 

Note: When using a 2-inch focal length lens, B 
corresponds to 2 degrees from the axis, C corre- 
sponds to 4 degrees from the axis, D corresponds to 
5 degrees from the axis, E corresponds to 6 degrees 
from the axis, and F corresponds to 3 degrees from 
the axis. 

Note: Glass test plates in accordance with this stand- 
ard are available from the Society of Motion Picture 
and Television Engineers, 40 West 40th Street, New 
York 18, N.Y. 



PH22.53-1953 



July 1953 Journal of the SMPTE Vol.61 



65 



1953 Convention of the NEA 
Department of Audio-Visual Instruction 



By D. F. LYMAN 



JL HE 1953 CONVENTION of the Depart- 
ment of Audio- Visual Instruction of the 
National Education Association was 
held in St. Louis, February 24 to 28. 
This year, with 727 registrants, the at- 
tendance was about twice that reported 
last year.* There were representatives 
from 42 states, two provinces of Canada, 
Pakistan, Thailand, the Philippines and 
Egypt. The writer of this review at- 
tended as a representative of the Society 
of Motion Picture and Television Engi- 
neers. 

Exhibits 

At the suggestion of a number of the 
members who went to the conference in 
Boston last year, arrangements had been 
made to have commercial exhibits in 
operation during this convention. There 
were 44 booths and 41 exhibitors. Their 
displays included the following items: 
16mm motion-picture projectors; 35mm 
still-picture projectors; opaque pro- 
jectors; details about motion-picture 
film libraries; sources of 35mm film 
strips; 16mm reels; tape recorders; 
printing materials; disc records; li- 
brary services; room-darkening mate- 
rials; equipment for handling, marking 
and storing films ; and projection screens. 

A report received on March 17, 1953. 
* D. F. Lyrnan, "Audio- Visual Con- 
ference," Jour. SMPTE, 58: 445-449, 
May 1952. 



Program 

Because of the way the conference was 
operated, the program is a major work 
in itself. It consists of a 5 X 7j inch 
booklet with 41 printed pages. It 
shows the sequence of preconference and 
conference meetings, the topics discussed 
in the separate meetings of the 13 sec- 
tions, the chairmen and recorders of all 
the meetings, long lists of "resource 
leaders" for the section meetings, the 
exhibitors and the layout of their space, 
and general information about the 
convention and the department. The 
great deal of work which must have 
gone into the booklet was a worthy 
effort, for it was one of the chief reasons 
for the smooth running of the convention. 

As at the previous convention, there 
were a few general sessions for the 
entire group of registrants, but much of 
the time was devoted to separate meet- 
ings of 1 3 discussion groups sponsored by 
national committees or sections. These 
committees, which are responsible for 
continual progress in their particular 
endeavors throughout the following year, 
receive a great deal of help from the 
ideas and suggestions expressed in the 
discussions held during the conventions. 
Brief reviews of some of the general 
sessions and section meetings are given 
below. 



66 



July 1953 Journal of the SMPTE Vol. 61 



General Sessions 

The first general session was a pres- 
entation of a selected group of films 
which had been rated as outstanding at 
recent European film festivals. 

At the main dinner meeting, the 
speaker was R. J. Blakely from the fund 
for Adult Education of the Ford Founda- 
tion. He described the investigations 
that are being made to determine how 
television can be applied most effectively 
in educational work, and the relation of 
television to other forms of mass com- 
munication such as newspapers, films, 
radio and picture magazines. 

In his president's message, J. W. 
Brown spoke of the continued growth of 
the DAVI organization, which had 
1066 members in 1951, 1381 in 1952, 
and now has 1755 in 1953. 

On Thursday morning, a still-picture 
film in color was presented with accom- 
panying sound on magnetic tape. It 
described and showed an experiment 
conducted in a Cleveland school located 
in an underprivileged area. Rapid 
advances were made by children of pre- 
reading age when audio-visual work on 
the subject of farms, presented over a 
period of several weeks, was supple- 
mented by a field trip to a farm. Ques- 
tions and answers recorded before, 
during, and after the experiment showed 
that the pupils made substantial general 
progress, as well as learning a great deal 
about farms and farmers. 

At this same meeting, Maurice Ahrens 
spoke on "The Role of Instructional 
Materials Specialists in Curriculum 
Development Programs." He outlined 
the transitions that have taken place in 
the development of curriculums, from 
textbooks alone to specialists in that 
type of work, then to teacher com- 
mittees, and finally to the more modern 
method that stresses development of a 
curriculum to suit each individual 
school. He emphasized that the ma- 
terials specialist and the materials 
laboratory should take a leading role in 



the operation of this most recent method. 
He believes that each school should have 
its own laboratory, but that the work of 
the individual laboratories should be 
correlated by a central laboratory, 
which is in a better position to plan 
budgets, for example. A materials 
specialist will find it necessary to work 
with groups of teachers in order to 
spread his efforts effectively. Further- 
more, he should help with plans for 
buildings, so that audio-visual aids can 
be used to their full advantage, work 
with principals and other consultants 
and specialists, provide a workshop and 
a community resource file, and facilitate 
the use of his materials. The facilities 
and functioning of such a center were 
illustrated by a 16mm film based on the 
school system of Corpus Christi, Texas. 

At another general session, a panel of 
speakers under the chairmanship of F. 
E. Brooker described some of the inter- 
national developments in the audio- 
visual field. Reports were made by 
DAVI members who have served abroad 
in the Mutual Security Agency or Point 
Four organizations. Included was the 
work done in the Philippines, France, 
Iran, Israel and India, as well as some 
of the coordinating work in Washington, 
D.C. A teacher from the Philippines 
and a student from Egypt gave further 
descriptions of audio-visual plans in 
their countries. 

Field Trip to Audio-Visual Center 

One of the best features of the con- 
vention was the open house at the 
Audio- Visual Education Building of the 
Division of Audio-Visual Education 
for the St. Louis public schools. There 
was ample opportunity to visit all the 
departments of this large audio-visual 
center and to talk with the hospitable 
members of its staff. In addition to 
the libraries, museums, laboratories 
and storage rooms, the building houses 
station KSLH, an FM radio station 
being operated as a part of the city's 
educational system. Sample films to 



D. F. Lyman: Audio- Visual Convention 



67 



show how local subjects can be kine- 
scoped and photographed for use on 
educational television programs were 
shown, respectively, by A. L. Hunter of 
Michigan State College and John 
Whitney of the St. Louis schools. 

Section Meetings 

Of the 13 Sections meeting during 
the week, Section 8, Buildings and Equip- 
ment, which the writer attended, is 
more closely allied than any of the others 
with the work of the Society of Motion 
Picture and Television Engineers. This 
Section considered a draft of a booklet 
on Audio- Visual Centers. This is the 
third to be published. No. 1 is Class- 
rooms* while No. 2, just issued, is 
Auditoriums. Although no final drafts 
were drawn during the meetings, there 
was a great deal of discussion about the 
following points : the scope of the booklet 
under consideration, ways to insure 
positive action in securing audio-visual 
centers, the functions the center must 
fulfill, how different schools and school 
systems should be covered, the distinc- 
tion between an "audio-visual center" 



* Ann Hyer, "Planning classrooms for 
audio-visual materials," presented on Oc- 
tober 7, 1952, at the Society's Convention 
at Washington, D. C., and scheduled for 
early Journal publication. Classrooms was 
reviewed in the Sept. 1952 Journal, and 
Auditoriums in April 1953. 



and an "instructional materials center," 
the advantages and disadvantages of pro- 
viding sample floor plans that would 
show architects how much space is 
needed for each function, the respective 
responsibilities of a coordinating center 
and a local center, how both types 
should be administered, how plans can 
be made for future growth and new 
materials, the best climatic conditions 
for "caring for" equipment and ma- 
terials, and the needs of those who are 
being called upon to change from a 
single-system building center to a central 
system that coordinates the work of a 
number of building centers. At times, 
the discussion seemed to show many 
points of difference, but when it is 
analyzed, it should be of great assistance 
to the small group that will write the 
next drafts of the booklet. 

Most of the sections had previously 
solicited the aid of "resource leaders" 
who had agreed to serve in that capacity 
and were called upon for suggestions, 
That method, and the frequent use of 
a panel of speakers in the general ses- 
sions, serves to enlist the capabilities of 
experts who otherwise might not be 
heard. This idea has interesting possi- 
bilities. In the case of resource leaders, 
more specific results could be obtained 
if each person were assigned or volun- 
tarily assumed some particular phase 
of the work. 



68 



July 1953 Journal of the SMPTE Vol. 61 



Theater Survey 



The eruption of technical innovations in 
the production and exhibition of motion 
pictures has given rise to a certain degree 
of confusion and hesitation. The last 25 
years have witnessed the development of 
sound and color and the beginnings of 
theater television. In the space of less than 
a year the industry has been swamped by 
Cinerama, 3-D, stereophonic sound, aspect 
ratios increased from 4:3 to 5:3, 5^:3, 
talk of 6:3 and CinemaScope 7f:3. 
These are being advocated singly and in 
various combinations. 

However there are several "unknowns" 
in these equations. Possibly of major sig- 
nificance is the question of structural limita- 
tions. Stated more fully, what shapes and 
sizes of pictures can be economically exhib- 
ited in enough theaters to become the 
practical basis for future standards? Also 
vital, is a statistical evaluation of the re- 
sponse of exhibitors to these developments 
whose adoption necessitates new financial 
investments. Theater owners, producing 
companies, equipment manufacturers and 
dealers, engineers and architects, all are 
concerned with the answers to these ques- 
tions. 

To secure effectively this desired informa- 
tion the Society's Theater Engineering 
Committee, with the cooperation of the 
Motion Picture Research Council, initiated 
at its last committee meeting, April 30, 
1953, a Theater Survey. The complete 
text of the survey questionnaire is published 



on the following pages. Distribution of the 
questionnaire, begun May 25, 1953, was 
made through the cooperation of the fol- 
lowing trade organizations: Motion Pic- 
ture Association of America, Theater 
Owners of America, Independent Theater 
Owners of America, Metropolitan Motion 
Picture Theaters Association, Allied States 
Association Theater Owners of America, 
Theater Equipment Dealers Association; 
also the following companies: National 
Theater Supply Company, Altec and RCA 
Service Companies and several large theater 
circuits ; and also upon request, directly to 
individual theaters as a result of the wide 
interest generated through nationwide pub- 
licity. 

Despite the seemingly haphazard distri- 
bution pattern, plans have been made to 
analyze the returns on a scientific basis 
giving due weight to such factors as geog- 
raphy, population density, seating capac- 
ity, distribution pattern of the different- 
sized theaters, etc. It is hoped thereby to 
come up with answers which are appli- 
cable industry-wide. After a sufficient 
number of returns (500 to 1000) are re- 
ceived to build up a valid statistical sample, 
the survey results will be published as a 
committee report in this Journal. It is ex- 
pected that this will help eliminate the 
confusion and hesitation and will provide 
a firm foundation for many of the impor- 
tant decisions yet to be made. Henry 
Kogel, Staff Engineer. 



July 1953 Journal of the SMPTE Vol. 61 



69 



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July 1953 Journal of the SMPTE Vol. 61 



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July 1953 Journal of the SMPTE Vol. 61 



71 



BACK WALL OF STAGE 



WIDTH OF 



STRUCTURAL OPENING 
PRESENT SCREEN 



CURTAIN LINE ' 



MAXIMUM PICTURE WIDTH UP TO 



EXIT DOORS OR OTHER OBSTRUCTIONS 



FIRST ROW OF SEATS 




WIDEST ROW OF SEATS 
NEAREST TO SCREEN 

LIST NUMBER OF SEATS a 

NUMBER OF AISLES 



NUMBER OF ROWS 



LAST ROW OF 



NUMBER OF ROWS OF , 

SEATS INCLUDING ' 

STADIUM SEATS IF ANY 



SEAT 





BACK OF HOUSE 



ORCHESTRA 



AISLES 



ROWS 



ROWS 



SEATS 



72 



DIAGRAM NS. I 

July 1953 Journal of the SMPTE Vol. 61 




o 
o 



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o 



DIAGRAM NO. 2 



July 1953 Journal of the SMPTE Vol. 61 



73 




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DIAGRAM N2. 3 



July 1953 Journal of the SMPTE Vol. 61 



74th Convention 



ON OCTOBER 5-9 at the Hotel Statler in New York will be presented a program of 
technical papers now being assembled by Skip Athey. If you have, or know about, 
a subject which should be on the program, wire or telephone anyone on the list 
below or anyone on the Papers Committee roster given in the April Journal. A sub- 
stantial number of papers is already arranged, but no worthy paper is as yet too late. 

Chairman: W. H. Rivers, Eastman Kodak Co., 342 Madison Ave., New York 17. 
74th Program Chairman: Skipwith W. Athey, c/o General Precision Laboratory, 16 

South Moger Ave., Mt. Kisco, N.Y. 

For Washington: J. E. Aiken, 116 No. Galveston St., Arlington 3, Va. 
For Chicago: Geo. W. Colburn, 164 N. Wacker Dr., Chicago 6, 111. 
For Canada: G. G. Graham, National Film Board of Canada, John St., Ottawa, 

Canada 
For 74th Convention High-Speed Photography : Charles A. Jantzen, Photographic Analysis 

Co., 100 Rock Hill Rd., Clifton, NJ. 

For Hollywood: Ralph E. Lovell, 2743 Veteran Ave., West Los Angeles 64, Calif. 
For High-Speed Photography: John H. Waddell, 850 Hudson Ave., Rochester 21, N.Y. 



Membership Service Questionnaire Analysis 

THE MEMBERSHIP SERVICE questionnaire which went out in January along with annual 
dues bills to all members in the U.S., except students, drew a response from 1296, 
or 44.1% a high return as such questionnaires go. The replies of the membership 
were the basis for the SMPTE Board of Governors' action reported in the June 
Journal chiefly that of authorizing a 20% increase in the size of the Journal. In 
response to membership demands for more tutorial and "how-to" papers, Editorial 
Vice-President Norwood Simmons has instructed the Papers Committee to apply 
greater effort in that direction. 

Comments or suggestions relating to Journal practices are in order at any time. 
However, after looking through the analysis, members may well feel prompted to 
express their personal point of view. In this connection open letters will be welcomed 
by Norwood Simmons, 6706 Santa Monica Blvd., Hollywood 38, Calif. 

The questions as they appeared in the questionnaire are shown below in boldface 
type, with tabulation by number of members and by percentage of the total of 1296 
replies. 

THE JOURNAL AND THE SOCIETY'S ACTIVITIES 

1. Do you find the Journal satisfactory as it is? 

Yes No Partly No Opinion 

900(69.4%) 67(5.2%) 115(8.9%) 214(16.5%) 

If you think that improvements should be made, would you say that: 
(a) articles are too obscure or technical? 

Yes No Partly No Opinion 

172(13.4%) 166(12.8%) 85(6.5%) 873(67.3%) 

75 



(b) articles should be more technical? 

Yes No Partly 

78(6.0%) 195(15.1%) 26(2.0%) 

(c) the Journal would be more useful if it contained more "how to" papers about 
TV films, magnetic editing, etc.? 



No Opinion 
997(76.9%) 



Yes No Partly 

550(42.4%) 51(4.0%) 15(1.1%) 

(d) Journal issues should contain more papers? 

Yes No Partly 

251(19.3%) 115(8.9%) 13(1.1%) 



2. What general criticism of the Journal 
can you offer and what suggestions 
would you make for improving it? 

I. GENERAL 

A. Subject Matter 

A general evaluation of comments shows a 
marked preoccupation with the balance between 
the cinematographic and television fields. The 
membership asks for treatment of the interrelated 
aspects of both fields with emphasis, on the one 
hand, on problems and developments in produc- 
tion, processing and projection of motion-picture 
film for television applications and, on the other, 
on television techniques making use of cine- 
matographic products and skills. 

B. Manner of Presentation 

The overwhelming demand is for descriptions 
and discussions that have practical application 
to members' own experience and work in the 
field. The membership asks for papers that are 
technical, but not purely theoretical, and written 
in a form acceptable to the greatest number. 
This means the avoidance, in so far as is possible, 
of detailed scientific theory, especially mathe- 
matical, and concentration on useful principles 
expressed in clear and simple language. 

II. SPECIFIC 

In the following listing of specific comments 
the order reflects in general the frequency with 
which the comment appears. Those most fre- 
quently occurring have been emphasized by a 
figure in parenthesis showing the actual number 
of times the comment was made. 

A. The content of the Journal should: 

1. be presented in a form designed to be of 
the greatest practical use to the majority of mem- 
bers, avoiding abstruse theory and emphasizing 
clarity and simplicity (36) ; 

2. include more and better photographs and 
diagrams (26), use color where possible (5) ; 

3. put more emphasis on techniques and de- 
velopments in the television field, with particular 
attention to those aspects involving motion pic- 
ture applications (33) ; 

4. devote more space to new products and 
developments, with evaluation (24); 



No Opinion 
680(52.5%) 



No Opinion 

917(70.7%) 



5. include more information on three-dimen 
sional films (18); 

6. give preference to cinematographic aspects 
of both motion-picture work and television (19); 

7. emphasize practical production problems 
rather than discussions of scientific and engineer- 
ing data (10); in particular, information should 
be given that would be helpful to the work of 
small production units (4) ; 

8. have more diversified coverage (7); 

9. give more attention to audio problems (7); 

10. consider theater and projection problems 
so as to be of practical assistance to exhibitors (7) ; 

1 1 . include tutorial articles designed to appeal 
to students and non-engineers (6) ; 

12. give more attention to discussion of aes- 
thetic standards (4) ; 

13. give more attention to the following: (a) 
color cinematography ; (b) reversal films for tele- 
vision; (c) foreign techniques, processes and 
equipment; (d) film processing and laboratory 
developments; (e) studio lighting; (f) industrial 
photography; (g) film recording; (h) electronic 
solutions; (i) personnel problems of the indus- 
try, including union regulations, etc.; (j) tech- 
niques of individual jobs in motion-picture and 
television fields. 

B. The content of the Journal should NO T: 

1. put so much emphasis on television (18); 

2. put so much emphasis on high-speed pho- 
tography (13); 

3. include so many articles on proprietary 
products written so as to give the impression of 
being disguised commercials (13); 

4. devote so much attention to : (a) film proc- 
essing; (b) magnetic recording; (c) electronics; 
(d) military research; (e) acoustics; (f) theater 
design. 

C. The Journal should: 

1. publish advertisements (11); 

2. present series of articles to cover whole 
scope of a specific subject from first principles to 
latest developments (7) ; 

3. include nontechnical summaries in difficult 
articles ; publish better summaries in general (6) ; 

4. provide a glossary of technical terms; 

5. in the first part of each article introduce the 



76 



subject and summarize the conclusions in non- 
technical terms; 

6. give an annual or semiannual review of im- 
portant developments in all fields in language 
understandable to the layman ; 

7. include reviews and abstracts of foreign 
publications; 

8. publish more book reviews; 

9. publish tutorial, "how to" articles sepa- 
rately in special editions or sections; 

10. include a question and answer section, 
with bibliographies; 

11. include a section for correspondence, 
"tips," "time-savers," etc.; 

12. give more space to advertising situations 
available and wanted ; 

13. publish more discussions at end of papers 
where possible; 

14. make available more special issues with col- 
lections of papers on related subjects; 

15. publish convention papers separately from 
the regular Journal material (which should there- 
fore be increased) ; 

16. give abstracts of all papers presented at 
conventions ; 

17. make available catalogs of motion-picture, 
television and still-photography equipment; 

18. include a section on news of the industry; 

19. give more space to letters to the editor; 

20. abstract important articles in other pub- 
lications; 

21. abstract highlights of important addresses 
before all sections of the Society (in editorial 
section) ; 

22. give space to news of membership and 
activities; 

23. reprint major standards periodically; 

24. include editorials; 

25. present subject matter arranged in cate- 
gories ; 

26. republish earlier important papers; 

27. give more information on how members 
can contribute to committee work and other 
Society activities; 

28. publish photographs and biographies of 
authors with their articles. 

D. General Statements 

1. Journal should appear on' time and reach 
members during month of publication (21). 

2. Convention papers should appear sooner 
after presentation (6). 

3. Timelier advance notice of meetings should 
be given. 

4. Tape recordings of discussions at conven- 
tions as well as of papers should be made avail- 
able. 

5. Officer nominations should be more evenly 
distributed by geographical areas. 

6. Format changes might include: (a) size 
increase to 81/2 by 1 1 ; (b) larger type; (c) rigid 
cover; (d) better index; (e) bi-monthly publica- 
tion; (f) loose-leaf reprint service. 



7. Send forms soliciting articles to all mem- 
bers. 

3. Mark your 1st and 2nd choices for 
future subject emphasis in the Jour- 
nal, or make suggestions: 





1st 


2nd 


Sug- 




Subject Choice 


Choice 


gested 


Total 


Acoustics 


22 


26 


102 


150 


Animation 


26 


18 


74 


118 


Cinema- 










tography 


92 


47 


150 


289 


Color 


110 


64 


155 


329 


Editing 


21 


32 


89 


142 


Education 


8 


19 


48 


75 


Films 


11 


17 


67 


95 


High-Speed 










Photog. 


61 


29 


69 


159 


Lighting 


23 


52 


130 


205 


New Products 


47 


53 


158 


258 


Optics 


39 


64 


134 


237 


Processing 


38 


48 


121 


207 


Production 


28 


43 


91 


162 


Projection 


35 


20 


102 


157 


16mm 


80 


58 


153 


291 


Sound 










Recording 


109 


67 


165 


341 


Sound 










Reproduction 


46 


68 


130 


244 


Studios 


7 


19 


74 


100 


Television 


131 


85 


169 


385 


Theater 


13 


11 


62 


86 


Theater 










Television 


27 


39 


108 


174 


Stereoscopy 


18 


9 


32 


59 


(written in) 











First, it should be noted that the "over- 
looked" subject of Stereoscopy drew a 
heavy write-in. 

Second, except for "Theater Television," 
the subject of television was not subdivided, 
but other portions of the Society's field 
are generally divided and subdivided 
sound, for instance, into recording and re- 
production. 

A recapitulation of subjects in order of 
number of total choices is : 



1. 


Television 


385 


11. 


Theater TV 


174 


2. 


Sound 




12. 


Production 


162 




Recording 


341 


13. 


High-Speed 




3. 


Color 


329 




Photog. 


159 


4. 


16mm 


291 


14. 


Projection 


157 


5. 


Cinematog- 




15. 


Acoustics 


150 




raphy 


289 


16. 


Editing 


142 


6. 


New Products 


258 


17. 


Animation 


118 


7. 


Sound Reprod. 


244 


18. 


Films 


95 


B. 


Optics 


237 


19. 


Theater 


86 


9. 


Processing 


207 


20. 


Education 


75 


10. 


Lighting 


205 


21. 


Stereoscopy 


59 



77 



CONVENTIONS 



4. Do you regularly attend conventions? 

Yes Occasionally No 

146(11.3%) 68(5.2%) 177(13.6%) 

No Opinion 

98(7.6%) 

Or only when they are held near 
you? 

807(62.3%) 

5. Do you think members would be bet- 
ter served if the customary Spring 
Convention were replaced by several 
regional meetings of two-day duration? 

Yes No Both 

539(41.6%) 366(28.2%) 6(0.5%) 
No Opinion 
385(29.7%) 



If in favor of two-day meetings, list 
choices of cities: 





1st 


Only 




City 


Choice 


Choice 


Total 


New York 


129 


60 


189 


Los Angeles 


71 


55 


126 


Chicago 


51 


27 


78 


Washington, D. C. 


16 




16 


San Francisco 


8 


3 


11 


Rochester 


9 


2 


11 



Cities receiving a total of 6 to 10 checks were: 
Atlanta, Boston, Cleveland, Dallas, Detroit and 
Philadelphia. 

Cities receiving a total of 1 to 5 checks were: 
Albuquerque, Austin, Cincinnati, Denver, El 
Paso, Fort Worth, Houston, Jacksonville, Kansas 
City, Lansing, Milwaukee, Nashville, New 
Haven, Phoenix, Pittsburgh, St. Louis, Salt Lake 
City, San Antonio and Seattle. 



MAGAZINES 

Members were asked to check a list of 
magazines. The tabulation will not be 
published because the Society cannot sup- 
ply comparative statistics about trade 
magazines. It may be said, however, that 
the results were consistent with subject 
choices indicated in Item 3 above. 



In comparison with the subject coverage 
of the magazines you have checked, 
does the SMPTE Journal: 



duplicate 

(partially duplicate) 
adequately supplement 
inadequately supplement 
(no opinion) 

Total 



11 (0.8%) 
10 (0.8%) 
(65.5%) 
(7.3%) 
(25.6%) 



849 

95 

331 



1296 (100%) 



PROFESSIONAL SOCIETIES 

Single check those of the following to which you belong. Make a second check at 
those with which a conflict of convention dates would be most serious: 

Society Two Checks 

Acoustical Society of America 14 

American Chemical Society 8 

American Institute of Electrical Engineers ... 8 

American Physical Society 2 

Audio Engineering Society 1 1 

Biological Photographic Association 8 

Illuminating Engineering Society 1 

Institute of Radio Engineers 68 

Instrument Society of America 4 

National Electronics Conference 7 

Optical Society of America 17 

Photographic Society of America 20 

Society of Photographic Engineers 22 

There were 38 societies' names written in. Of these, only two attained as much as a 
total of 10 write-ins each. They were the American Association for the Advancement of 
Science and the American Society of Photogrammetry. D.C. 



One Check 


Total 


38 


52 


53 


61 


59 


67 


40 


42 


58 


69 


20 


28 


14 


15 


189 


257 


18 


22 


29 


36 


55 


72 


125 


145 


63 


85 



78 



Status of Motion-Picture Standards 



Standards, withdrawals and proposals are shown below according to their status 
as of February 1953. The six-month index, published as Part II of the June 1953 
Journal (p. 761), brings the list as published below up to date. 

A "New Index to American Standards and Recommendations," of eight full pages, 
is available at no charge to all who request it from Society Headquarters, regardless 
of whether it is to go into a binder. Copies should be obtained to replace earlier 
indexes in all SMPTE binders of standards. 

If you have an SMPTE (3-post) binder and would like to receive advance notice 
of all future new and revised standards, please advise Society Headquarters. 

The complete assembly of heavy binder and the 75 current standards is now avail- 
able at $15.00 (plus 3% sales tax on deliveries within New York City; or plus $0.50 
extra for postage on foreign orders). 

Subject Vol., page, issue 

Apertures, Camera 

8mm Z22.19-1950 54: 501, Apr. 1950 

16mm Z22.7 -1950 54: 495, Apr. 1950 

35mm Z22.59-1947* 50: 287, Mar. 1948 

Apertures, Printer 

16mm Contact (positive from negative) .... Z22.48-1946 46: 300, Apr. 1946 

16mm Contact (reversal dupes) Z22.49-1946 46: 301, Apr. 1946 

35mm to 16mm (16mm positive prints) .... Z22.46-1946 46: 298, Apr. 1946 

35mm to 16mm (16mm dupe negative) .... Z22.47-1946 46: 299, Apr. 1946 

16mm to 35mm Enlargement Ratio PH22.92-1953 60: 72, Jan. 1953 

Apertures, Projector 

8mm Z22.20-1950 54: 503, Apr. 1950 

16mm Z22.8 -1950 45: 498, Apr. 1950 

35mm Sound Z22.58-1947* 50: 286, Mar. 1948 

Cores for Raw Stock Film 

16mm PH22.38-1952 59: 429, Nov. 1952 

35mm Z22.37-1944 47: 262, Sept. 1946 

Density Measurements of Film Z22.27-1947 50: 283, Mar. 1948 

(includes Z38.2.5-1946) 

Edge Numbering, 16mm Film PH22.83-1952 59: 428, Nov. 1952 

Film Dimensions 

8mm Z22.17-1947* 49: 176, Aug. 1947 

16mm Silent Z22.5 -1947* 59: 529, Dec. 1952 

16mm Sound Z22.12-1947* 59: 531, Dec. 1952 

32mm Negative and Positive, Sound Z22.71-1950 56: 237, Feb. 1951 

32mm Negative and Positive, Silent Z22.72-1950 56: 239, Feb. 1951 

32mm on 35mm Negative PH22.73-1951 56: 685, June 1951 

35mm Negative Z22.34-1949 52: 358, Mar. 1949 

35mm Positive Z22.36-1947* 49: 179, Aug. 1947 

35mm Alternate Positive-Negative PH22.1 -1953 60: 67, Jan. 1953 



The asterisk denotes that the standard was in process of revision, as of February 1953. 

79 



Subject 

Film Usage, Camera 

8mm 

1 6mm Double Perforated . . 
16mm Single Perforated . 
35mm 

Film Usage, Projector 

8mm 

1 6mm Double Perforated . 
16mm Single Perforated . . 
35mm. 



Focus Scales, 16mm and 8mm Cameras . 

Lamps, 16mm and 8mm Projectors 

Base-Up Type 

Base-Down Type 



Vol., page, issue 

Z22.21-1946* 46: 291, Apr. 1946 

Z22.9 -1946* 46: 289, Apr. 1946 

Z22.15-1946* 57: 581, Dec. 1951 

Z22.2 -1946* 46: 287, Apr. 1946 



Z22.22-1947* 
Z22.10-1947* 
Z22.16-1947* 
Z22.3 -1946* 



49: 557, Dec. 1947 
49: 555, Dec. 1947 
57: 582, Dec. 1951 
46: 288, Apr. 1946 



PH22.74-1951 56: 687, June 1951 



PH22.84-1953 60: 69, Jan. 1953 
PH22.85-1953 60: 71, Jan. 1953 



Lens Mounting, 16mm and 8mm Cameras . . PH22.76-1951 56: 688, June 1951 

Nomenclature, Film Z22.56-1947* 50: 275, Mar. 1948 

Projection Rooms and Lenses Z22.28-1946* 47: 259, Sept. 1946 

Reels 

8mm Z22.23-1941* 36: 241, Mar. 1941 

16mm (corrected) PH22.11-1952* 58: 535, June 1952 

35mm Z22.4 -1941* 36: 222, Mar. 1941 

Reel Spindles, 16mm PH22.50-1952 59: 525, Dec. 1952 

Release Prints, 35mm Z22.55-1947* 50: 284, Mar. 1948 

Safety Film Z22.31-1946* 47: 261, Sept. 1946 

Screen 

Brightness Z22.39-1944* 58: 452, May 1952 

Dimensions. . Z22.29-1948 51: 535, Nov. 1948 

Mounting Frames Z22.78-1950 54: 505, Apr. 1950 

Sound Transmission PH22.82-1951 57: 171, Aug. 1951 

Sound-Track Dimensions 

16mm. . . Z22.41-1946* 46: 293, Apr. 1946 

35mm Z22.40-1950 56: 114, Jan. 1951 

35mm Double Width Push-Pull, Normal .... Z22.69-1948 51: 547, Nov. 1948 

35mm Double Width Push-Pull, Offset Z22.70-1948 51: 548, Nov. 1948 

Splices 

8mm PH22.77-1952 58: 541, June 1952 

16mm. . . ,-. PH22.24-1952 58: 539, June 1952 

Sprockets 

16mm (SMPTE Recommended Practice) 

35mm. . . . . . '; . . Z22.35-1947* 49: 178, Aug. 1947 

Test Films 

16mm 400-Cycle Signal Level ; . . . Z22.45-1946* 46: 297, Apr. 1946 

3000-Cycle Flutter . . . .,-.-... . Z22.43-1946 46: 295, Apr. 1946 

5000-Cycle Sound Focusing 

7000-Cycle Sound Focusing Z22.42-1946* 46: 294, Apr. 1946 



80 



Subject 

Buzz-Track Z22.57-1947* 

Multi-Frequency Z22.44-1946 

Travel Ghost Z22.54-1946* 

Sound Projector Z22.79-1950 

Scanning Beam, Laboratory TyP e 

(corrected) PH22.80-1950 

Scanning Beam, Service Type (corrected ) PH22.81-1 950 

35mm 1000-Cycle Balancing Z22.67-1948 

7000-Cycle Sound Focusing Z22.61-1949 

9000-Cycle Sound Focusing Z22.62-1948 

Buzz-Track Z22.68-1949 

Scanning Beam, Laboratory Type. . . . Z22.66-1948 

Scanning Beam, Service Type Z22.65-1948 

Theater Test Reel. . Z22.60-1948 



Test Methods, 16mm Sound Distortion 

Cross Modulation, Variable- Area . . 
Intermodulation, Variable-Density . 

Test Plate 

Resolution Target, 16mm Projector . 



Z22.52-1946 
Z22.51-1946 



Vol., page, issue 

51: 537, Nov. 1948 
46:296, Apr. 1946 
46: 309, Apr. 1946 
54: 507, Apr. 1950 



59: 430, Nov. 
59: 430, Nov. 
51: 545, Nov. 
54: 107, Jan. 
51: 541, Nov. 
54: 108, Jan. 
51: 543, Nov. 
51: 542, Nov. 
51: 539, Nov. 



1952 
1952 
1948 
1950 
1948 
1950 
1948 
1948 
1948 



46: 305, Apr. 1946 
46: 303, Apr. 1946 



. . Z22.53-1946* 46: 307, Apr. 1946 



Standards Withdrawn 

No. Title 

Z22.6 -1941 Projector Sprockets for 16mm Film 

Z22.13-1941 For current standard see Z22.7-1950 Camera Aper- 
ture for 16mm Sound Film 

Z22.14-1941 For current standard see Z22.8-1 950 Projector Aper- 
ture for 16mm Sound Film 

Z22. 18-1 941 8-Tooth Projector Sprockets for 8mm Motion Pic- 
ture Film 

Z22.25-1941 American Recommended Practice for Film Splices 

Negative and Positive for 16mm Sound Film 
(See PH22.24) 

Z22.26-1941 American Recommended Practice for Sensitometry 

Z22. 30-1 941 American Recommended Practice for Nomenclature 

Z22.32-1941 Cancelled 

American Recommended Practice for Motion Picture 

Film, Theater Sound Fader Setting Instructions 
American Recommended Practice for Fader Setting 
Instructions 

Z22.33-1941 (Notice of Withdrawal) American Recommended 
Practice for Nomenclature for Filters 

Z22.63 Proposed, Service-Type Multifrequency Test Film 

for 35mm Motion Picture Sound Reproducers 

Z22.64 Laboratory-Type Multifrequency Test Film for 

35mm Motion Picture Sound Reproducers 



Vol., page, issue 

36: 224, Mar. 1941 
36: 231, Mar. 1941 

36: 232, Mar. 1941 
36:236, Mar. 1941 
36:243, Mar. 1941 



36: 244, 
36: 248, 
50: 276, 
48: 390, 

36: 250, 
59: 252, 
50: 275, 
50: 275, 



Mar. 1941 
Mar. 1941 
Mar. 1948 
Apr. 1947 

Mar. 1941 
Mar. 1941 
Mar. 1948 
Mar. 1948 



Proposed Standards 

PH22.75 Proposed, A and B Windings of 16mm Single-Perforated 60: 189, Feb. 1953 

Film (Third Draft) 
PH22.86 Proposed, Dimensions for Magnetic Sound Tracks on 57: 72, July 1951 

35mm and 17 1 / 2 nim Motion Picture Film 



81 



No. Title Vol., page, issue 

PH22.87 Proposed, Dimensions for Magnetic Sound Track on 57: 73, July 1951 

16mm Motion Picture Film 
PH22.88 Proposed, Dimensions for Magnetic Sound Track on 8mm 57: 74, July 1951 

Motion Picture Film 

PH22.89 Proposed, Printer Light Change Cueing for 16mm Mo- 
tion Picture Negative (not at Journal publication stage; 

available as mimeographed proposal) 

PH22.90 Proposed, Aperture Calibration of Motion Picture Lenses 59: 338, Oct. 1952 
PH22.91 Proposed, 16mm Motion Picture Projector for Use with 59: 144, Aug. 1952 

Monochrome Television Film Chains Operating on 

Full-Storage Basis (Fourth Draft) 
PH22.93 Proposed, 35mm Motion Picture Short Pitch Negative 59: 533, Dec. 1952 

Film 
PH22.94 Proposed, Slides and Opaques for Television Film Chains 

(published April 1953) 



Photographic Apparatus and Processing Standards 



BELOW ARE LISTED the numbers and 
titles of recently approved American 
Standards in the field of still photography. 
Additional listings of such standards will 
be published in the Journal from time to 
time, as they are made available, as a 
service to those readers who maintain an 
active interest in still, as well as motion- 
picture, photography. Henry Kogel, 
Staff Engineer. 

Photographic Apparatus, PH3 

Back Window Location for Roll Film 
Cameras, PH3.1-1952 (Revision of 
Z38.4.9-1944) 

Method for Determining Performance 
Characteristics of Focal-Plane Shut- 
ters Used in Still Picture Cameras, 
PH3.2-1952 (Replaces American War 
Standard Z52.65-1946) 

Exposure-Time Markings for Focal- 
Plane Shutters Used in Still Picture 
Cameras, PH3.3-1952 (Replaces Pro- 
posed American War Standard Z52. 
64) 

Method for Determining Performance 
Characteristics of Between-the-Lens 
Shutters Used in Still Picture Cameras, 
PH3.4-1952 (Replaces American War 
Standard Z52.63-1946) 



Exposure-Time Markings for Between- 
the-Lens Shutters Used in Still Pic- 
ture Cameras, PH3.5-1952 (Replaces 
American War Standard Z52.62- 
1946) 

Tripod Connections for American Cam- 
eras, i-Inch-20 Thread, PH3.6-1952 
(Revision of Z38.4.1-1942) 

Tripod Connections for Heavy-Duty 
or European Cameras, f- Inch -16 
Thread, with Adapter for f-Inch-20 
Tripod Screws (Revision of Z38.4.2- 
1942), PH3.7-1952 

Photographic Processing, PH4 

Specifications for Sheet Film Processing 
Tanks, PH4.2-1952 (Revision of Z38.8. 
15-1949) 

Specifications for Photographic Trays, 
PH4.3-1952 

Specifications for Channel-Type Photo- 
graphic Hangers, Plates and Sheet 
Film, PH4.4-1 952 

Specification for Photographic Grade 
Sodium Acid Sulfate, Fused, (Na 
HSO 4 ), (Sodium Bisulfate, Fused; 
Niter Cake), PH4.105-1952 

Specification for Photographic Grade 
Sodium Sulfite, (Na 2 SO 3 ), PH4.275- 
1952 (Revision of Z38.8.275-1948) 



82 



New Test Films 



A folder of addenda to the Society's Test Film Catalog is now available at no charge 
from the Society's headquarters. Details of five new 35mm test films are listed, de- 
signed for 3-D and 2-D projector alignment, magnetic 3-track balancing, magnetic 3- 
track azimuth alignment, magnetic 3-track flutter test and magnetic 3-track multi- 
frequency test. There is also a 16mm magnetic azimuth alignment test film. These 
films have been approved by technical committees of the Society and of the Motion 
Picture Research Council. 



Theater Television 



Only by its appeal will theater television 
survive, for FCC Docket 9552 is now closed 
by a finding of June 24, Commissioner 
Hennock dissenting. The Commission 
speaks : 

"... theatre television should operate as 
a common carrier on frequencies presently 
allocated for such services, we of course ex- 
pect that there will be cooperation among 
common carriers in resolving frequency 
conflicts. . . . There has been no persuasive 
evidence in this proceeding to the effect that 
the existing common carrier allocations are 
not adequate. ... In any event, we do not 
feel this is the proper proceeding to re- 
evaluate the sufficiency of present alloca- 
tions to the common carrier service. ... If 
the proponents of theatre television feel 
that existing common carriers cannot sup- 
ply them with the service they desire, they 



are free to take the necessary steps to estab- 
lish a separate carrier ... or to require 
existing carriers to render a reasonable 
service. . . . We recognize [theater televi- 
sion in general] as an existing service which 
will continue to expand or not depending 
upon public acceptance and support 
thereof. . . . Our concern is merely with the 
question of whether there should be a sepa- 
rate allocation of frequencies for the exclu- 
sive use of this service. Finding that there 
is no necessity for such an allocation, we 
have decided that this proceeding should 
now be terminated." Note: Commissioner 
Hennock believes the hearing incomplete, 
the finding unwarranted since "public 
interest" was not specifically determined 
and, in opposing, draws critical inference 
that ". . . this question will be decided when 
a specific application for service is filed. "- 
B.N. 



Book Reviews 



The Television Manual 

By William Hodapp. Published (1953) by 
Farrar, Straus and Young, 101 Fifth Ave., 
New York 3, N.Y. i-xiv, 289 pp. text -f 
5 \ pp. index. 5^ X 8| in. Not illustrated. 

This book, as stated by the publishers, 
is a "guide to TV production and program- 
ming for education, public affairs and enter- 
tainment." It is a very good book from 
this point of view, and is no doubt directed 
toward that group of workers in television 
broadcasting who are intimately concerned 



with the business of building and producing 
programs to satisfy the insatiable appetite 
of this demanding new entertainment 
medium. As a program guide, it fills a 
real need in the field of television broadcast- 
ing. 

Although not a technical book in any 
sense, it will prove of interest to those engi- 
neering and technical workers in the field 
who might feel the need of an authoritative 
work on television production and program- 
ming techniques, and for this purpose it 
should prove a valuable addition to the tele- 



83 



vision engineer's reference library. Be- 
cause of the author's practical experience 
with NBC, the information contained in 
this volume can be considered authoritative 
as well as practical. 

The author discusses program formats 
and sources, production and operations, 
studio and remote settings, staging, films 
for television, educational TV operation, 
the personnel engaged in producing a 
complete television program on the air and 
their various duties and responsibilities. 
There is an interesting discussion of tele- 
vision today and tomorrow. 

A well-prepared appendix provides some 
very excellent information for new people 
entering the field of television program- 
ming as well as station management. For 
new television station managers this vol- 
ume will be a helpful place to find practical 
information concerning important phases 
of station operation, typical network costs, 
standard business contract forms, a glossary 
of TV production terms, recommended 
sources of information for further study, etc. 

The book would have been vastly im- 
proved through the addition of some care- 
fully selected illustrations, and it is hoped 
that in his second edition the author will 
make up for this deficiency. Scott Helt, 
Allen B. Du Mont Laboratories, Inc., 750 
Bloomfield Ave., Clifton, N.J. 



Designing for TV, 

The Arts and Crafts in Television 

By Robert J. Wade. Published (1953) by 
Pellegrini and Cudahy, 101 Fifth Ave., New 
York 3, N.Y. 203 pp. + 12 pp. index. 
Numerous illus. 8 X 11$ in. $8.50. 

The time is ripe for specialized and 
definitive books on the various aspects of 
the new television medium. Television 
engineering has long since passed from ex- 
perimentation into practical day-to-day 
operation, and television production too has 
borrowed what it must from the techniques 
of stagecraft, from motion pictures, from 
display advertising and a dozen other 
fields, passed through the experimental 
period and is settling down into a fairly well 
standardized television technique. 

Designing for TV is a book for the set de- 
signer, the graphic artist, and naturally for 
the director as well, since the very intensity 



of production in this medium demands that 
everyone have a pretty clear idea of the 
other man's problems. It will be particu- 
larly valuable for the TV station production 
manager, who must decide on the type of 
scenery to be built, the space necessary for 
construction and painting, and must devise 
short-cut techniques ("nickel-tricks" as 
Chuck Holden calls them at ABC) to get 
"almost the same effect" at negligible time 
and cost. Wade's book is frankly a glam- 
our-book, lavishly supplied with illustra- 
tions, many of which seem to occupy a lot 
of space without conveying too much actual 
information. Yet the solid stuff is there 
and the glamour factor should add greatly 
to the inspirational value of the book when 
it falls into the hands of students of the 
medium. 

Although described by the author as a 
reference book, Designing for TV is written 
in such a personable style that one fre- 
quently looks up a subject and finds him- 
self beguiled into reading well beyond his 
topic. It conveys a feeling of immediate 
contact with the medium, of getting "the 
straight stuff right from the horse's mouth" 
which is invaluable in a book of this kind. 
Wade is candid in his accuracy: "dis- 
temper colors," he reports, "include a 
palette of hot unpleasant browns, screech- 
ing yellows, an assortment of half-caste 
putty gamboges and pinks ... a rather 
beautiful turquoise [etc.]." He is honest 
in his opinions. In discussing the cameo 
technique, a method of producing dramatic 
shows largely in close shots with a black 
background, he has this to say: "While 
graphic artists for obvious reasons do not 
cotton to this technical development, the 
method has many excellent features and 
provides means of presenting certain types 
of dramatic fare in an atmosphere of inti- 
macy. The viewer, not always without 
some embarrassment, is enabled to watch 
and to eavesdrop at close range during 
emotional scenes and can observe, if he 
has the clinical interest, enlargements of 
varied eyes, ears, noses and throats react- 
ing to different stimuli." 

Although priced nearly in the luxury 
class, this book should have wide usefulness. 
It belongs in every television library and 
close at hand on every production man's 
desk. Rudy Bretz, Television Consultant, 
Park Trail, Croton-on-Hudson. N.Y. 



84 



Home Music Systems: 
How to Build and Enjoy Them 

By Edward Tatnall Canby. Published 
(1953) by Harper & Brothers, 49 E. 33d 
St., New York 16, N.Y., i-x, 296 pp. text + 
4 pp. index. Illus. 5J X 8 in. Price 

$3.95. 

Mr. Canby, who regularly reviews rec- 
ords in Audio Engineering, is clearly aiming 
his book at the considerable audience that 
follows his reviews and also at the ever- 
growing number of good-sound enthusiasts 
interested in choosing and installing their 
own sound equipment. Primarily intended 
for the amateur intent on getting the ut- 
most out of his commercial LP records, the 
book has a store of clearly expressed in- 
formation on the theory and performance of 
each component of a sound system 
turntables, pickup heads, preamplifiers, 
amplifiers and speakers as well as on the 
various refining gadgets now available to 
go with them. There is good practical 
guidance on quality and price of equipment 



offered on the market, and much helpful 
advice is given on speaker enclosures and 
other aspects of home installation. This 
should be a handy reference book even lor 
the sound engineer, who is all too likely 
these days to !>< in frequent demand for 
informal help with living-room music 
systems. D.C. 



Scientific Film Review 

This is a new quarterly of criticism being 
issued by the Scientific Film Association in 
London, as a supplement to the Monthly 
Film Bulletin of the British Film Institute. 
It is distributed to all members of those 
two organizations and may be obtained by 
others from the General Secretary, Scien- 
tific Film Association, 164 Shaftesbury 
Ave., London W.C.2. The first issue con- 
tained full details on 17 new films, ranging 
from purely scientific instructional films on 
electricity to films on engineering, textiles 
and medicine. 



Current Literature 



The Editors present for convenient reference a list of articles dealing with subjects cognate to motion 
picture engineering published in a number of selected journals. Photostatic or microfilm copies of 
articles in magazines that are available may be obtained from The Library of Congress, Washington, 
D.C., or from the New York Public Library, New York, N. Y., at prevailing rates. 



American Cinematographer 

vol. 34, Apr. 1953 
An Animation Stand for TV Film Production 

(p. 162) W. R. Witherell, Jr. 
The Magnasync Recorder (p. 165) D. J. White 
The New Ansco Color Film and Process (p. 166) 

R. A. Mitchell 

vol. 34, May 1953 
2-D, 3-D, Wide-Screen, or All Three (p. 210) 

A. Gavin 

Columbia Studio's 3-D Camera (p. 215) 
Filming the Big Dimension (p. 216) L. Shamroy 
Terror in 3-Dimension (p. 218) H. A. Lightman 

vol. 34, June 1953 
Some Basic Principles of 3-D Cinematography 

(p. 266) F. A. Ramsdell 
One Camera, One Film for 3-D (p. 269) 
A New Camera Dolly for Films and Television 

(p. 273) K. Freund 
The Hallen Magnetic Film Recorder (p. 274) 

H. Powell 



Audio Engineering 

vol. 37, May 1953 

Handbook of Sound Reproduction, Chapter 1 1 : 
Loudspeaker Mounting (p. 34) E. M. Villchur 

vol. 37, no. 7, July 1953 

Handbook of Sound Reproduction, Chapter 12: 
The Power Amplifier, Pt. 1 (p. 26) E. M. Vill- 
chur 



Bild und Ton 

Umfeldbeleuchtung bei 
(p. 67) R. Reuther 

Entwicklungsstand der 
Bildtonanlagen fiir 
G. Pierschel 



vol. 6, Mar. 1953 
der Kinoprojektion 

Bildprojektoren und 
16-mm-Film (p. 80) 



British Kinematography 

vol. 22, Mar. 1953 

Aerial Filming for "The Sound Barrier" (p. 68) 
A. Squire 



85 



Pinewood Studios. A Review of Recent Techni- 
cal Developments (p. 76) R. L. Hoult 

The Film Studio. The Development of Equip- 
ment and Operation (p. 78) B. Honri 

vol. 22, Apr. 1953 
The Quality of Television and Kinematograph 

Pictures (p. 104) L. C. Jesly 
Observations on Cine-Stereoscopy (p. 100) 

vol. 22, May 1953 
Modern Tendencies in 16mm Projector Design 

(p. 140) C. B. Watkinson 
Eastman Colour Films for Professional Motion 

Picture Work (p. 146) G. J. Craig 

vol. 22, June 1953 

The Flammability and Flash Point of Cellulose 
Acetate Film Containing Various Amounts of 
Cellulose Nitrate (p. 172) R. W. Pickard and 
D. Hird 

Production Techniques in the Making of Educa- 
tional Films (p. 176) F. A. Hoare 

International Photographer 

vol. 25, Apr. 1953 
From "Talkers" to 3-D (p. 5) T. Krasner, V. 

Heutschy and R. Ross 
Prismatic Color Corrector (p. 12) 

vol. 25, June 1953 

Processing Color Film (p. 22) G. Ashton and P. 
Jenkins 



International Projectionist 

vol. 28, Apr. 1953 
CinemaScope: What it is, How it Works (p. 7) 

A. Gavin 
Types of Theatre Sound Reproducers. Pt. IV, 

The Sound-head (p. 11) R. A. Mitchell 
World-Premiere of Altec-Paramount 4-Projector, 

No Intermission, 3-D Color Showing (p. 15) 

vol. 28, May 1953 

Visibility Factors in Projection. Pt. 1, Pano- 
rama vs. Stereoscopy (p. 7) R. A. Mitchell 
Projected Light and the Curved Screen (p. 12) 
The "New" Cooling Systems (p. 13) C. A. Hahn 
Addendum: 3-D Projection: Motion Picture 

Research Council (p. 14) 
Motiograph's Stereo Sound (p. 14) 

vol. 28, June 1953 
Wide Screen Single-Film 3-D Predicted (p. 7) 

J. A, Nor ling 
Visibility Factors in Projection. Pt. 2, Light 

Problems of 3-D and Panorama (p. 11) R. A. 

Mitchell 
The "Hypergonar" Lens Process (p. 14) H. 

Chretien 



Journal of the Audio Engineering Society 

vol. 1, no. 2, Apr. 1953 

History and Development of Stereophonic Sound 
Recording (p. 176) R. H. Snyder 



Kino-Technik 

vol. 7, May 1953 
Der Raumfilm in der Debatte: Internationale 

Umschau der 3-D-Filmtechnik (p. 126) L. 

Busch 
Plastischer Film im Blickfeld der Patentschriften 

(p. 129) H. Atorf 
Das Raumbildton-Verfahren System Klangfilm 

"Stereodyn" (p. 132) H. Friess 
Stereoskopie muss durch Stereophonic erganzt 

werden (p. 134) M. Ulner 
Das Stereofilm-Verfahren System Zeiss Ikon (p. 

136) 0. Vierling 

vol. 7, no. 6, June 1953 
Untersuchungen und Erfahrungen mit Sicher- 

heitsfilm (p. 156) A. Narath 
Sicherheits- und Nitrofilmnach Brennbarkeit 

verglichen (p. 158) 
Plastischer Film im Blickfeld der Patentschriften 

(p. 162) H. Atorf 
Technische Hinweise zur Stereo-Filmvorfuhrung 

(p. 164) H. Tiimmel 



Motion Picture Herald 

vols. 190 and 191 Mar. 14, 1953 (p. 30); 

Apr. 4 (p. 28); Apr. 25 (p. 24); May 9 (p. 23); 
June 13 (p. 19). 

A series of installments on "The Story of 3-D 
from 1613 to 1953" by Martin Quigley, Jr. 
The previous sections of this article were pub- 
lished in the issues of Feb. 7 (p. 16) and Feb. 
21 (p. 14) 

vol. 192, July 4, 1953 

Single Film 3-D Claimed by Norling (p. 23) 

Motion Picture Herald (Better Theatres Sec.) 

vol. 192, July 4, 1953 

Crisis in Sound, 1953 (p. 11) 

Precision Requirements of 3-D: Shutter Syn- 
chronization, Interlocking and Alignment 
(p. 15) G. Gagliardi 

Philips Technical Review 

vol. 14, Apr. 1953 

A Steel Picture-Tube for Television Reception 
(p. 281) J. de Gier, T. Hagenberg, H. J. Meer- 
kamp van Embden, J. A. M. Smelt and 0. L. 
van Steenis 



Radio & Television News 

vol. 50, July 1953 
The Dage Industrial TV Camera (p. 31) H. E. 

Ennes 

Tele-Tech 

vol. 12, July 1953 
Color Television Its Status Today and a Look 

into the Future (p. 54) W. R. G. Baker 
Multicon A New TV Camera Tube (p. 57) 

H. Smith 



86 



Obituaries 



Herbert Griffin died on May 6, 1953, at 
Santa Monica, Calif. He was Vice-Presi- 
dent and a Director of International Pro- 
jector Corp. 

Born in London in 1887, he was educated 
there and in the U.S. and was subsequently 
associated with several engineering firms. 
In 1915 he joined Nicholas Power Co., 
makers of projectors, and, except for an 
excursion as director of motion-picture 
activities for the YMCA with the AEF from 
1916 to 1919, he stayed with Nicholas 
Power until the firm merged with Inter- 
national Projector Corp., makers of Sim- 
plex projectors. He became Vice-Presi- 
dent and a Director of that firm in 1936. 

Herbert Griffin will be especially remem- 
bered by the Society's members as one 
active in its affairs for many years. He was 
President in 1943-44 and a Fellow. 




Leopold E. Greiner, Jr., President of 
Greiner Glass Industries Company of 
New York, died in May 1 953. Mr. Greiner 
had pioneered in the precision etching of 
various glass devices for use in motion- 
picture equipment. He was responsible for 
the design and production of the widely 
used 16mm Projector Lens Resolution 
Target which is based on American Stand- 
ard Z22.53. 



Riborg Graf Mann died at his home in 
East Hampton, N.Y. on June 13, 1953. 
He was 52 years old. 

After graduation from the Massachusetts 
Institute of Technology, where he was a 
member of the Student Army Training 
Corps of World War I, he entered the 
radio and motion-picture field. In 1927 



he joined the Lee DeForest Laboratories 
where he performed experimental work on 
motion-picture sound equipment. In 1928 
he traveled extensively for Movietone News, 
both in this country and abroad, pioneering 
in the making of sound newsreels. He then 
transferred to Trans-Lux where he helped 
build their first Newsreel Theater in New 
York. For the past 20 years he had been 
Chief Engineer of Pathe News. 

During World War II, Mr. Mann was 
given a leave of absence from Pathe and 
served for 36 months in the United States 
Coast Guard Reserve. He attained the 
rank of Lieutenant-Commander, com- 
manding a Destroyer Escort both in the 
Atlantic and Pacific areas. 

He had been a member of the Society of 
Motion Picture and Television Engineers 
since 1934. 



SMPTE Lapel Fins 



The Society has available for mailing its gold and blue enamel lapel pin, with a screw 
back. The pin is a -in. reproduction of the Society symbol the film, sprocket and 
television tube which appears on the Journal cover. The price of the pin is $4.00, 
including Federal Tax; in New York City, add 3% sales tax. 



87 



New Members 



The following members have been added to the Society's rolls since those last published. The 
designations of grades are the same as those used in the 1952 MEMBERSHIP DIRECTORY. 

Student (S) 



Honorary (H) 



Fellow (F) 



Active (M) 



Associate (A) 



Adams, Robert A., Sound Engineer, Consoli- 
dated Amusement Co., Honolulu, Hawaii. 
(A) 

Alder, Sidney M., Sales Engineer, Minnesota 
Mining & Mfg. Co., 6411 Randolph St., Los 
Angeles, Calif. (A) 

Alexander, John, University of Southern Cali- 
fornia. Mail: 3049 Royal St., Los Angeles 7, 
Calif. (S) 

Alexander, Richard G., Film Technician, Film- 
service Laboratory. Mail: 11720 Magnolia 
Blvd., North Hollywood, Calif. (M) 

Alf, Herbert A., Motion-Picture Producer. 
Mail: 6245 Scenic Ave., Los Angeles 28, 
Calif. (A) 

Allen, J. Longworth, University of Southern 
California. Mail: 643 W. 30 St., Los 
Angeles 7, Calif. (S) 

Andersen, Helmer W., Television Recording, 
Columbia Broadcasting System. Mail: 2337 
Lake View Ave., Los Angeles 39, Calif. (A) 

Applegate, Vernon C., Fishery Research Bi- 
ologist, United States Fish and Wildlife 
Service, P.O. Box 28, Rogers City, Mich. (A) 

Arndt, Jack E., Motion-Picture Sound Service, 
Altec Service Corp. Mail: 925 Buckingham 
St., S.W., Grand Rapids, Mich. (A) 

Arnold, Leroy H. J., University of Southern 
California. Mail: 1615 Crenshaw Blvd., 
Torrance, Calif. (S) 

Arriola, William A., Photographer and Motion- 
Picture Technician, Alexander Film Co. 
Mail: 214| East Dale, Colorado Springs, 
Colo. (M) 

Babet, Philip, University of California at Los 
Angeles. Mail: 904 1 Tiverton Ave., Los 
Angeles 24, Calif. (S) 

Bachrach, Ernest A., Portrait Photographer, 
RKO Studio. Mail: 5612 Canyonside Rd., 
La Crescenta, Calif. (A) 

Balousek, Ray, Photographer, 24 Custer St., 
Detroit, Mich. (A) 

Barden, Ron, University of Southern California. 
Mail: 1138 W. 28 St., Los Angeles 7, Calif. 
(S) 

Baribault, Phillip, Sound-Cameraman, 124 
North Lincoln St., Burbank, Calif. (A) 

Beemer, Richard N., Motion-Picture Writer, 
Director, North American Aviation, Inc. 
Mail: 4547| Carson St., Long Beach 8, 
Calif. (A) 

Beiswenger, Bruce R., Assistant Film Director, 
Television Station WHAM-TV. Mail: 96 
Fernwood Park, Rochester 9, N.Y. (M) 
Benson, Rupert M., Jr., University of Southern 
California. Mail: 4959 Cahuenga Blvd., 
North Hollywood, Calif. (S) 



Beyoghlian, Agop, University of Southern 
California. Mail: 1533 Fourth Ave., Los 
Angeles 19, Calif. (S) 

Bolm, Olaf A., TV Commercials (Film), Young 
& Rubicam, Inc. Mail: 2061 North Syca- 
more Ave., Hollywood 28, Calif. (A) 

Bomke, Robert A., University of Southern 
California. Mail: 14834 Lakewood Blvd., 
Paramount, Calif. (S) 

Borschcll, E. J., Sound Engineer, Wayne Fel- 
lows, Prods., Inc., 1022 Palm Ave., Hollywood 
46, Calif. (A) 

Bowder, James I., Cinemaphotographer, 
Hughes Aircraft Co. Mail: 7422 South 
Harvard Blvd., Los Angeles 47, Calif. (A) 

Bowen, David, Cinematographer, Hughes 
Aircraft Co. Mail: 561 3| North Hunting- 
ton Dr., Los Angeles, Calif. (A) 

Bullock, Edward A., Engineer, Technical Serv- 
ice, Inc., 30865 W. Five Mile Rd., Livonia 
Mich. (M) 

Burson, H. E., Jr., Motion-Picture Specialist, 
Hughes Aircraft Co. Mail: 3347 Canfield 
Ave., Los Angeles 34, Calif. (A) 

Calderon, Ruben A., Owner, Azteca Films, 
Inc., 1743 South Vermont Ave., Los Angeles, 
Calif. (A) 

Carlisle, Kenneth S., Projectionist, Fox Inter- 
Mountain Amusements. Mail: 936 Glad- 
stone, Sheridan, Wyo. (A) 

Cartwright, William Tilton, University of South- 
ern California. Mail: 6232 La Mirada, 
Apt. 2, Los Angeles, Calif. (S) 

Chatterjee, Sushilkumar, University of South- 
ern California. Mail: 4240| Third Ave., 
Los Angeles 8, Calif. (S) 

Chylousky, Edward, University of Southern 
California. Mail: 2260 Cranston Rd., Uni- 
versity Heights 18, Ohio. (S) 

Cohen, Robert C., Production Designer. Mail: 
177 South Sycamore Ave., Los Angeles 36, 
Calif. (A) 

Con way, Robert E., Projectionist, Fox West 
Coast Theatres. Mail: 171530 St., San 
Diego 2, Calif. (A) 

Cookley, Stephen, University of Southern Cali- 
fornia. Mail: 1116 North Garfield Ave., 
Alhambra, Calif. (S) 

Cozzens, Warren B., Sales Engineer. Mail: 
220 Kedzie St., Evanston, 111. (M) 

Craddock, Douglas L., Radio and Theatre 
Operator. Mail: Leaksville, N.C. (A) 

Crandall, Roland D., Animated Motion-Picture 
and Television Cartoons. Mail: 31 Heusted 
Dr., Old Greenwich, Conn. (A) 



88 



Cravens, Charles, University of Southern 
California. Mail: 942 W. 34 St., Los 
Angeles 7, Calif. (S) 

Cummings, Carol, University of Southern Cali- 
fornia. Mail: 1215 Lodi PI., Los Angeles 
38, Calif. (S) 

Cummings, George, Mini Technician, Peerless 
Laboratories, 55 Dell Park Ave., Toronto, 
Ontario, Canada. (A) 

Dahgdevirian, Charles, Laboratory Film Tech- 
nician, Acme Film Laboratory, Inc. Mail: 
4735 Oakwood Ave., Los Angeles 4, Calif. 
(A) 

Davis, Jesse F., Cameraman, Cutter, 1790 
Winona Blvd., Los Angeles 27, Calif. (A) 

De Angelis, Maj. Luigi, Motion-Picture 
Cameraman and Producer, U.S. Air Force. 
Mail: 7208 La Presa Dr., Hollywood 28, 
Calif. (A) 

Dembo, Samuel, 871 Seventh Ave., New York 
19, N.Y. (A) 

Dixon, Thomas L., Color Film Duplication, 
Sawyers Inc., Box 490, Portland, Ore. (A) 

Dodge, George F., University of Southern 
California. Mail: 8000 Honey Dr., Los 
Angeles 46, Calif. (S) 

Donaldson, Wallace C., Cameraman, Canadian 
Television Films, 53 Yonge St., Toronto, 
Ontario, Canada. (A) 

Dorsey, Harry, University of Southern Cali- 
fornia. Mail: 833 W. 28 St., Los Angeles 7, 
Calif. (S) 

Doughty, E. E., Laboratory Technician, Gen- 
eral Films Laboratory Corp. Mail: 4238 
Riverton Ave., North Hollywood, Calif. (A) 

Dzur, Albert A., University of Southern Cali- 
fornia. Mail: 1043 W. 35 St., Los Angeles, 
Calif. (S) 

Dzur, Carolyn Crage, University of Southern 
California. Mail: 1043 W. 35 St., Los 
Angeles, Calif. (S) 

Eastwood, Clive, Professional Engineer, Radio 
Station CFRB, 37 Bloor St., West, Toronto, 
Ontario, Canada. (A) 

Eberenz, Robert W., Motion-Picture Projec- 
tionist and Sound Technician, W. S. Butter- 
field Theatres, Inc. Mail: 1023 Martin 
St., Jackson, Mich. (A) 

Ely, Julian B., University of California at Los 
Angeles. Mail: 1738 Bentley Ave., Los 
Angeles 25, Calif. (S) 

Engelberg, Phil R., Laboratory Superintendent, 
Modern Movies Laboratories, Inc. Mail: 
1147 North Coronado St., Los Angeles, Calif. 
(M) 

Freeman, John Norman, Motion-Picture Cam- 
eraman, North American Aviation. Mail. 
350 South Harvard Blvd., Los Angeles, Calif, 
(A) 

French, Howard E., University of Southern 
California. Mail: 1138 W. 28 St., Los 
Angeles 7, Calif. (S) 



Fulmer, Harold M., TV Broadcast Engineer, 
Wrather-Alvarez Broadcasting, Inc., KFMB- 
TV. Mail: 1214 Thomas Ave., San Diego 
9, Calif (A) 

Fulmis, Mike J., University of California ai l.<^ 
Angeles. Mail: 3297 Glendon Ave., Los 
AnRfl.-s, ( :.ilil. (S) 

Garinger, Truman, University of Southern 
California. Mail: 1283 Browning Blvd., 
Los Angeles 37, Calif. (S) 

Gebhart, Wilford W., Film Engineer, WSM- 
TV. Mail: 2000 Castleman Dr., Nashville, 
Tenn. (M) 

Geier, Jane H., Layout Draftsman, (iillill-m 
Bros. Mail: 300 South Mariposa St., Bur- 
bank, Calif. (A) 

George, Royford Verden, University of South- 
ern California. Mail: 3437 Warwick Ave., 
Los Angeles, Calif. (S) 

Gibson, William John, Motion-Picture Photog- 
rapher, U.S. Air Force. Mail: 10531 Pine- 
wood Ave., Tujunga, Calif. (M) 

Glennon, Lawrence E., Jr., Industrial Engineer, 
Photographic Equipment, Signal Corps Pic- 
torial Center. Mail: 15 Hatch Tcr., Dobbs 
Ferry, N.Y. (M) 

Gould, Arthur, Director, Cameraman, Naval 
Ordnance Test Station. Mail: 1253 North 
Orange Dr., Los Angeles, Calif. (A) 

Grant, Arthur, Projectionist and Sound Tech- 
nician, Metropolitan Theatres Co. Mail: 
P.O. Box 73231, Ascot Station, Los Angeles 3, 
Calif. (A) 

Gregg, R. Richard, Manager, Sales and Installa- 
tions, Fonda Corp., 550 West Colorado St., 
Glendale 4, Calif. (M) 

Griffing, William E., Motion-Picture Producer. 
Mail: 105 Park Ave., East Orange, N.J. 
(A) 

Gross, Edith, University of California at Los 
Angeles. Mail: 801 Levering Ave., Los 
Angeles 24, Calif. (S) 

Hagopian, J. Michael, University of Southern 
California. Mail: 8000 Honey Dr., Holly- 
wood 46, Calif. (S) 

Hale, William Ballenger, University of Southern 
California. Mail: 804 El Centre, Holly- 
wood 38, Calif. (S) 

Halligan, George, Film Editor, Producer, 6938 
Coldwater Canyon, North Hollywood, Calif. 
(A) 

Hansard, Robert L., Process Projection Engi- 
neer. Mail: 12607 Martha St., North 
Hollywood, Calif. (M) 

Hanson, Harold E., Harolds Photo & TV, 1105 
South Lake Ave., Sioux Falls, S.D. (A) 

Harmony, Don, Timer and Printer, Geo. W. 
Colburn Laboratory. Mail: c/o K. H. 
Shuttle, 228 East Huron, Chicago 11, 111. 
(A) 

Harnett, David L., University of Southern 
California. Mail: 1140 W. 27 St., Los 
Angeles, Calif. (S) 



89 



Haun, James J., Motion-Picture Writer, Direc- 
tor, Engineer, North American Aviation. 
Mail: 5501 Orange Ave., Apt. 5, Long 
Beach, Calif. (A) 

Hawes, Hildreth G., 16mm Producer, Maine 
Department of Agriculture. Mail: 3 Middle 
St., Hallowell, Me. (A) 

Hawkins, Richard C., Teacher, University of 
California at Los Angeles. Mail: 1870| 
Kelton, Los Angeles, Calif. (A) 
Heath, Clyde, General Illustrator (Publications 
and Movies), Engineering Div., Navy Supply 
Depot. Mail: P.O. Box 122, Arlington, 
N.J. (M) 

Heilmann, Philip Eugene, Gordos Corp. 
Mail: 19 Metlars La., Durham Park, New 
Brunswick, N.J. (A) 

Henderson, Donald E., Production Assistant, 
Churchill-Wexler Film Productions. Mail: 
14016 Gain St., Pacoima, Calif. (A) 
Henderson, Ralph A., Sales Engineer, Minne- 
sota Mining & Manufacturing Co., 900 
Fauquier Ave., St. Paul, Minn. (M) 
Hogsett, Alice E., University of Southern 
California. Mail: 6302 Beck Ave., North 
Hollywood, Calif. (S) 

Hooper, R. B., Owner, Producer, Sonochrome 
Pictures. 2275 Glencoe St., Denver 7, Colo. 
(M) 

Jackson, Joseph M., Department Manager, 
Motion-Picture Photographic Dept., Owens- 
Illinois Glass Co., 14th and Adams, Toledo 1, 
Ohio. (M) 

Jewell, Stuart V., Cinema tographer, Walt Dis- 
ney Studios. Mail: 3848 Lomina Ave., 
Long Beach 8, Calif. (M) 

Tohnson, William W., Camera Technician, 
Paramount Pictures Corp. Mail: 5880 
Locksley PL, Los Angeles 28, Calif. (A) 
Jury, Harold William, Engineer-in-Charge, 
KNXT, Columbia Broadcasting System. 
Mail: 17260 Osborne St., Northridge, Calif. 
(M) 

Kautzky, Rudolf W., Branch Manager, Altec 
Service Corp. Mail: 4106 Case St., Elm- 
hurst 73, N.Y. (M) 

Kendall, Richard S., University of Southern 
California. Mail: 1636 North Vistas, Holly- 
wood 46, Calif. (S) 

Kent, Dave, University of Southern California. 
Mail: 901 Exposition, Los Angeles 7, Calif. 
(S) 

Kershner, Irvin, University of Southern Cali- 
fornia. Mail: 12225 Magnolia Blvd., North 
Hollywood, Calif. (S) 

Ketchum, Northrop H., Kinescope Recording 
Laboratory Coordinator, National Broad- 
casting Co. Mail: 18552 Collins St., Tar- 
zana, Calif. (A) 

Keto, Jorma Raymond, Electro-Mechanical 
Engineer, National Bureau of Standards. 
Mail: 305 Dean Dr., Rockville, Md. (A) 



King, Robert E., Technical Director, American 
Broadcasting Co. Mail: 3931 Prospect, 
Hollywood 27, Calif. (A) 

Knudsen, Orlando Stephen, Manager, Visual 
Aids Production, Iowa State College, Alice 
Norton House, Ames, Iowa. (M) 
Kontos, Spero L., Manager, Abbott Theatre 
Equipment Co., 1311 South Wabash Ave., 
Chicago, 111. (A) 

Lange, Peter, University of Southern California. 
Mail: 1815^ North Kingsley Dr., Hollywood 
27, Calif. (S) 

Larsen, Robert W., Production Manager, Mer- 
cury International Pictures, Inc., 6611 Santa 
Monica Blvd., Los Angeles, Calif. (M) 
Larsen, Seth Beegle, Motion-Picture Film 
Editor, Processor, Larsen Co. Mail: 451 
South Highland Ave., Los Angeles 36, Calif. 
(M) 
Larson, Robert H., Chief Engineer, DuKane 

Corp., St. Charles, 111. (M) 
Legris, John, University of Southern California. 
Mail: 3827 Hepburn Ave., Los Angeles, 
Calif. (S) 

Levy, Joseph, Film Technician, De Luxe 
Laboratories. Mail: 1346 Clay Ave., New 
York, N.Y. (A) 

Lindenbaum Elaine, University of Southern 
California. Mail: 10472 Lindbrook Dr., 
Los Angeles 24, Calif. (S) 

Lin vail, A. R., Cinema tographer, 16mm Tech- 
nical, North American Aviation. Mail: 
8606 Charloma Dr., Downey, Calif. (A) 
Lutes, Harold R., Optical and Photographic 
Engineer, Owner, H. L. Instrument Co. 
Mail: 313 W. Valley Blvd., San Gabriel, 
Calif. (M) 
Macauley, Mrs. Jan T., World Films, P.O. 

Box 72, Sierra Madre, Calif. (A) 
Manoogian, Haig A., City College of New York. 
Mail: 130 Post Ave., New York 34, N.Y. 
(S) 

Marker, Thomas P., In Charge, Motion-Picture 
Activities, Public Relations Dept., Chrysler 
Corp., 341 Massachusetts Ave., Detroit 31, 
Mich. (M) 

Marshall, Lauriston C., Director of Research, 
Research Laboratory, Link-Belt Co., 220 
South Belmont, Indianapolis, Ind. (M) 
McCartney, Earl, Senior Project Engineer, 
Marine Engineering Division, Sperry Gyro- 
scope. Mail: 2 Winding Rd., Rockville 
Centre, N.Y. (A) 

McEvoy, Earl E., Motion-Picture Producer, 846 
North Cahuenga Blvd., Hollywood 38, Calif. 
(A) 

McNulty, Barney, University of California at 
Los Angeles. Mail: 4434 Morse Ave., 
North Hollywood, Calif. (S) 
Meroz, Robert L., Field Service Engineer, De 
Vry Corp. Mail: 31 Albatross Rd., Levit- 
town, L.I., N.Y. (A) 

Merrick, M. J., Optical Engineer, Sawyer's 
Inc., P.O. Box 490, Portland 7, Ore. (M) 



90 



Miller, Clarence R., Service Engineer, RCA 
Service Co. Mail: P.O. Box 563, San 
Angelo, Tex. (A) 

Miller, Henry J., University of Southern Cali- 
fornia. Mail: 4547 J St. Elmo Dr., Los 
Angeles 19, Calif. (S) 

Moore, Russell G., District Manager, Bell & 
Howell Co. Mail: 8 Dojean Ct., Bergen- 
field, N.J. (A) 

More, Jerry, University of Southern California. 
Mail: 669 W. 34 St., Los Angeles 7. (S) 

Morin, Volney F., Resident Counsel, Techni- 
color Motion Picture Corp., 6311 Romaine 
St., Hollywood 38, Calif. (A) 

Morris, Nelson, Producer, 538 Fifth Ave., New 
York, N.Y. (M) 

Most, David, Instructor, New York University; 
Technical Consultant, Rush Instrument Co. 
Mail: 1716 Avenue T, Brooklyn 29, N.Y. 
(A) 

Murray, James V., Assistant Cameraman, Tech- 
nicolor Motion Pictures Inc. Mail: 5816 
Whitsett, North Hollywood, Calif. (A) 

Myers, Albert, Motion-Picture Camera Oper- 
ator, Frank Wisbar Productions. Mail: 
1936 North Alexandria Ave., Los Angeles 27, 
Calif. (A) 

Newell, John I., Motion-Picture Laboratory 
Technician, Western Cine Service, 114 E. 
Eighth Ave., Denver, Colo. (A) 

Nishimura, Ryosuke, Technical Director, Koni- 
shiroku Photo Ind. Co., Ltd., Konishiroku, 
Kaken, 6838, Hinomachi, Tokyo, Japan. 
(M) 

Noble, Richard, University of Southern Cali- 
fornia. Mail: 904 W. 28 St., Los Angeles 7, 
Calif. (S) 

Pavel, Eric, Technical Director, Pan American 
Press & Film Ltd., Rua Xavier de Toledo, 
264-7, Sao Paulo, Brazil. (M) 

Pera, Capt. William, Office of the Chief Signal 
Officer, Army Pictorial Service Division, 
Room 5A1058, Pentagon, Washington, D.C. 
(A) 

Perlov, Arthur, Technical Director, Radio Rec- 
ord TV. Mail: Rua Monte Libano, 19, 
Nitero, E. do Rio, Brazil. (A) 

Pierce, Raymond C., Jr., Assistant Cameraman, 
Unifilms, Inc., 146 E. 47 St., New York, N.Y. 
(A) 

Pittard, R. L., University of Southern California. 
Mail: 3316 San Marino, Los Angeles, Calif. 
(S) 

Poniatoff, Alexander M., President, Director of 
Engineering, Ampex Electric Corp. Mail: 
561 Eaton Ave., Redwood City, Calif. (A) 

Pontius, Frank E., Television Engineer (Kine- 
scope Recording), National Broadcasting Co. 
Mail: 5255| Hermitage Ave., North Holly- 
wood, Calif. (M) 

Poulis, William G., General Manager, Canadian 
Television Films, 53 Yonge St., Toronto, 
Ontario, Canada. (A) 



Printy, Virgil M., Test Engineer, Trclmii .1! 
Products Co. Mail: 11051 Emclita St., 
North Hollywood, Calif. (M) 

Raguse, Elmer R., Sound Director, Hal Roach 
Studio. Mail: 1244 South Beverly Glen 
Blvd., Los Angeles 24, Calif. (M) 

Ramsdell, Floyd A., Motion-Picture Producer, 
Worcester Film Corp., and Stereo Corp., 131 
Central St., Worcester, Mass. (M) 

Reynertson, Audrey Joan, University of Cali- 
fornia. Mail: 11678 Montana Ave., Los 
Angeles 49, Calif. (S) 

Richter, George W., Laboratory Operator, 
Richter's Film Laboratory, 1715 North Mari- 
posa Ave., Los Angeles 27, Calif. (M) 

Robins, Wiley W., University of Southern Cali- 
fornia. Mail: 528 Ruberta Ave., Glendalc 
1, Calif. (S) 

Robinson, Carl C., Photographic Chemist, 
Alexander Film Co. Mail: 815 East Dale 
St., Colorado Springs, Colo. (M) 

Rose, Nicholas, Psychologist, University of 
Southern California. MaU: 5060 W. 
Twelfth, Los Angeles 1 9, Calif. (A) 

Ross, John F. M., Graphic Associates Film Pro- 
duction Ltd., 1111 Bay St., Toronto, Ontario, 
Canada. (A) 

Rummage, J. Reid, University of Southern 
California. Mail: 1637| Arapahoe St., Los 
Angeles 6, Calif. (S) 

Rush, David H., Owner, Rush Instrument Co. 
Mail: 1 Fisher Dr., Mount Vernon, N.Y. 
(A) 

Rutledge, Donovan L., Chief Photographer, 
Beech Aircraft Corp. Mail: 124 South 
Charles, Wichita 1 2, Kan. (A) 

Sanders, Terry B., University of California at 
Los Angeles. Mail: 2881 Coldwater Can- 
yon Dr., Beverly Hills, Calif. (S) 

Sargent, Robert E., Television Engineer, 
American Broadcasting Co. Mail: 660 
Ocean Ave., Richmond, Calif. (A) 

Schnebel, Charles, University of California at 
Los Angeles. Mail: 1700 Manning, Los 
Angeles 24, Calif. (S) 

Selsted, Walter T., Chief Engineer, Ampex 
Electric Corp. Mail: 3960 Martin Dr., San 
Mateo, Calif. (A) 

Sherman, Reuel A., Director, Occupational 
Vision, Bausch & Lomb Optical Co., Roches- 
ter, N.Y. (M) 

Siegmund, Walter P., Scientific Aide to Vice- 
President of Research, American Optical Co., 
Southbridge, Mass. (A) 

Simon, Ernest M., Sound Engineer, Audio- 
Visual Department, Syracuse University. 
Mail: 950 East Livingston Ave., Columbus, 
Ohio. (M) 

Smith, Donald P., Sales, Custom Projection 
Equipment and Screens, Commercial Picture 
Equipment, Inc. Mail: 1107 South Chase 
St., Wheaton, 111. (A) 



91 



Smith, Harry R., Supervisor, Visual Education 
Branch, Department of Education, 244 College 
St., Toronto, Ontario, Canada. (A) 
Smith, Sidney S., Electronic Design Engineer, 
Link Aviation, Inc. Mail: 517 Castle St., 
Geneva, N.Y. (M) 

Snody, Robert R., Motion-Picture Unit Produc- 
tion Manager and Director, 20th Century-Fox 
Films, Via Goito 60, Rome, Italy. (M) 
Solomon, Berel David, Electronics Engineer, 
Physicist, Physics Dept., University of Miami. 
Mail: 1301 Lenox Ave., Miami Beach 39, 
Fla. (A) 

Stevens, Clarence T., Recording Engineer, 
Moulin Studios, 181 Second St., San Fran- 
cisco 5, Calif. (M) 

Stockert, Henry A., University of Southern 
California. Mail: Apt. B, 921 South Adams, 
Glendale 5, Calif. (S) 

Stringfellow, William M., Chief Engineer, 
WSPD-AM, FM, TV, Storer Broadcasting 
Co., 136 Huron St., Toledo, Ohio. (M) 
Stuber, F. L., Maine Employment Security 
Training Officer. Mail: R #1, River Rd., 
Richmond, Me. (A) 

Sutherland, J. Paul, Motion-Picture Tech- 
nician, 189 Sutherland Dr., Toronto, Ontario, 
Canada. (A) 

Swink, George E., Assistant Head, Editorial 
Dept., RKO Radio Pictures, Inc., 780 North 
Gower St., Hollywood, Calif. (A) 
Syracusa, Rudolf, Laboratory Technician, Tri- 
color Laboratories. Mail: 6332 Cren- 
shaw, Los Angeles 43, Calif. (A) 
Tarr, Eric Gordon, University of Southern 
California. Mail: 4507 Tenth Ave., Los 
Angeles 43, Calif. (S) 

Tavris, Eugene, University of Southern Cali- 
fornia. Mail: 1812 Western, Los Angeles, 
Calif. (S) 

Thie, Dean A., University of Southern Cali- 
fornia. Mail: 4035 W. 60 St., Los Angeles 
43, Calif. (S) 

Tremper, Richard E., Motion-Picture Writer 
and Director, North American Aviation. 
Mail: 900 Luray St., Long Beach 7, Calif. 
(A) 

Tschume, George G., Manager, Photographic 
Sales Dept., Scientific Instrument Division, 
Bausch & Lomb Optical Co., 635 St. Paul St., 
Rochester 2, N.Y. (M) 

Urban, Jack C., Professional Engineer (Me- 
chanical). Mail: 10533 Sarah St., North 
Hollywood, Calif. (M) 

Vellani, Antonio, University of Southern Cali- 
fornia. Mail: 2036 North Beachwood, 
Hollywood 28, Calif. (S) 



Vlack, Robert C., University of Southern Cali- 
fornia. Mail: 2258 Luana La., Montrose, 
Calif. (S) 

Ward, Richard H., Television Technician, 
WRGB, General Electric Co., 60 Washington 
Ave., Schenectady, N.Y. (A) 
Watkins, Richard, Northwestern University. 
Mail: 4654 Milwaukee Ave., Chicago 30, 111. 
(S) 

Wells, Clifford, Machinist, Ace Film Labora- 
tories, Inc. Mail: 2105 Avenue Z, Brooklyn 
35, N.Y. (A) 

West, George R., University of Southern Cali- 
fornia. Mail: 5629 Ensign St., North Holly- 
wood, Calif. (S) 

Widing, C. George, Laboratory Engineer. 
Mail: 8764 Beverly Blvd., Los Angeles, 
Calif. (A) 

Williams, Fred G., Assistant General Manager 
and Vice-President, Consolidated Amusement 
Co., Ltd., 25 Taylor St., Suite 706-8, San 
Francisco 2, Calif. (A) 

Wisniewski, Ray, University of Southern Cali- 
fornia. Mail: 804 El Centro, Los Angeles, 
Calif. (S) 

Wolfman, Augustus, Editor, Photography Pub- 
lishing Corp., 251 Fourth Ave., New York 10, 
N.Y. (A) 

Wood, Capt. Richard A., Army Pictorial, Signal 
Corps. Mail: 3311 Fordham Rd., Academy 
Gardens, Philadelphia 14, Pa. (A) 
Woolery, Adrian D., Motion-Picture Producer, 
Playhouse Pictures, 749 North Highland Ave., 
Los Angeles, Calif. (A) 

Yamin, Robert H., TV Productions, ZIV Tele- 
vision Programs, 5255 Clinton St., Los Ange- 
les, Calif. (A) 

Young, John W., Lecturer, Motion-Picture 
Division, University of California. Mail: 
10551 Scenario La., Los Angeles 24, Calif. 
(A) 

Zacarias, Ruben, University of Southern Cali- 
fornia. Mail: 4317 Kenwood Ave., Los 
Angeles 37, Calif. (S) 

Zuber, James, University of Southern Cali- 
fornia. Mail: 10415 South Noover St., Los 
Angeles, Calif. (S) 



DECEASED 

Griffin, Herbert, Vice-President, International 

Projector Corp. Mail: 1615 Cordova St., 

Los Angeles 7, Calif. (F) 
Mann, Riborg G., Chief Engineer, Pathe News, 

Inc., 625 Madison Ave., New York 22, N.Y. 

(M) 



SMPTE Officers and Committees: The roster of Society Officers and the 
Committee Chairmen and Members were published in the April Journal. 



92 



New Products 



Further information about these items can be obtained direct from the addresses given. As in the 
case of technical papers, the Society is not responsible for manufacturers' statements, and publica- 
tion of these items does not constitute endorsement of the products. 




The Metlen Dryer, to process photographic 
recording paper more quickly, rather than 
more slowly, than it is used, has been de- 
veloped and placed on the market by the 
Metlen Manufacturing Co., P.O. Box 2186, 
Seattle, Wash. Formerly, 200-ft lengths of 
from one to 20 rolls were exposed in an 8-hr 
day, but took 2 to 3 days to process. This 
dryer will dry a 200-ft roll of photographic 
recording paper in 10 to 16 min, depending 
on the width and type of paper. 

After being developed, the wet paper is 
wound on a large spool at the receiving end 
of the dryer. From this spool the paper is 
run through squeegies and then between 
the drying chambers to a rewind core, 
which is driven by a 1/10-hp 110-v electric 
motor with a resistor control to determine 
drying speed, regulated according to 



width and quality of paper. After it is 
dried the roll of paper is slipped off the 
core. 

All metal parts of the squeegies which 
remove the surplus water from the paper 
are of stainless steel. The drying chambers 
between which the paper travels have an 
arrangement of eighteen 375-w 110-v com- 
mercial drying bulbs. The paper travels 
between these two heat chambers held in 
place by a drying screen of fine-mesh stain- 
less steel. The top half of the dryer is fluted 
so as to create heat and moisture circula- 
tion, vaporizing the moisture and removing 
it with the excess heat from the drying 
chamber. The free flow of moisture and 
heat from the dryer results in the short dry- 
ing period. 



93 




The Kelly Cine Calculator is designed to 
provide in compact and easily operable 
form a means for establishing such 35mm 
cinematography data as these: (on front 
side, shown above) hyperfocal distance and 
depth of focus; (on reverse side, not shown) 
film speed per second; aperture scales (T- 
stops have been added for the users' con- 
venience and are based on existing Techni- 
color-to-/ stop values ; it is not claimed that 
they necessarily represent absolute trans- 



mission values); filter factors, camera 
speed-to-aperture; shutter angle-to-aper- 
ture; field of view; key-light and many 
other factors. The Calculator comes in 
two models: one for 35mm which is also 
useful for Leica, Contax and minicam fans ; 
and another for 8-1 6mm. List price is 
$3.95, including complete instruction man- 
uals. Made in England, sole distributors 
for U.S. and South America are Florman 
& Babb, 70 W. 45 St., New York 36. 




The F &B Film Footage Counter has been 
introduced by Florman and Babb, 70 West 
45th St., New York 36, N.Y. The dual 
model is a re-settable, synchronous film 
counter in 16mm and 35mm, on which 
either one or both may be selected by a 
switch. Monitor lights indicate whether 
the counter is in operation. With another 
selector, the unit can be switched to either 
"Sync" or "Line" position. In "Sync" 
position, the selector by-passes other 
switches in the unit, thus giving free way 
and interlocking with the synchronous 



94 



power supplied by a projector, a dubber, 
etc. In "Line" position the unit will be 
manually started and stopped by a small 
On-Off switch. 

On the back plate of the unit, a standard- 
sized receptacle will furnish a 110-v 60- 
cycle sync line for a minute and seconds 
counter, cueing signal, script reading light 
or other accessories. 

In order to assure a smooth and quiet 
drive, the high torque, low-speed syn- 



chronous motors are nylon geared and 
equipped with special lubricants. The unit 
starts and stops within 1 cycle ('/o sec). 

Florman & Babb arc ;tlso introducing 
small single 16mm and 35mm footage 
counters with simplified construction, as 
well as a time counter unit which reads up 
to 99 min and 59 sec. This time counter 
can be plugged in to any of the dual or 
single footage counter units for complete 
footage and time readings. 



Employment Service 



These notices are published for the service of the membership and the field. They are inserted for 
three months, and there is no charge to the member. 

Positions Available 



Wanted: Motion-picture processing tech- 
nicians for employment at U.S. Naval 
Ordnance Test Station, China Lake, Calif. 
Operators of Models 10 and 20 Houston 
motion-picture processing machines, and 
operators of Bell & Howell Models "D" and 
"J" motion-picture printers are needed. 
Civil Service positions $3,410 per annum 
base pay. Family housing limited; single 
persons preferred. Obtain Form 57 from 
any U.S. Post Office, fill out in detail, and 
mail to Carlos H. Elmer, 410B Forrestal, 
China Lake, Calif. 

Senior Engineer with leading supplier of 
motion-picture and TV equipment is 
looking for an associate in the development 
of film and tape handling equipment and 
other fine electromechanical devices. Give 
resume of professional experience and 
range of interest and accomplishments by 
letter to W. R. Isom, 1203 Collings Ave., 
Oaklyn, N.J. 

Wanted: Two design engineers, must be 
familiar with camera and precision instru- 
ment design. A working knowledge of 
machine shop practice essential. Salaries 
commensurate with ability. Send resume 
of experience and personal details in letter 
to: Land-Air Inc., 900 Pennsylvania 
Ave., Alamogordo, N.M. 

Wanted: Optical Engineer for permanent 
position with manufacturer of a wide 
variety of optics including camera objec- 
tives, projector, microscope and telescope 



optics, etc. Position involves design, de- 
velopment and production engineering. 
Send resume of training and experience to 
Simpson Optical Mfg. Co., 3200 W. Carroll 
Ave., Chicago 24, 111. 

Wanted: Personnel to fill the 4 classifica- 
tions listed below, by the Employment 
Office, Atten: EWACER, Wright-Patter- 
son Air Force Base, Ohio: 
Film Editor, GS-9: Must have 5 yrs. 
experience in one or more phases of motion - 
picture production. Experience must 
include at least 1 yrs. motion-picture 
film editing with responsibility for syn- 
chronization of picture, narration, dia- 
logue, background music, sound effects, 
titles, etc. $5060 yr. 

Photographic Processing Technician 
(Color) GS-7: 6 yrs. progressively re- 
sponsible experience in motion-picture 
photography and/or photographic labora- 
tory work, involving essential operation 
of film processing. Eighteen months of 
this experience must have involved proc- 
essing of color film. $4205 yr. 
Photographic Processing Technician 
(Black-and-White) GS-7: 6 yrs. pro- 
gressively responsible experience in motion - 
picture photography and/or photographic 
laboratory work, involving essential opera- 
tion of film processing. $4205 yr. 
Photographic Processing Technician 
(Black-and-White) GS-5: 1\ yrs. pro- 
gressively responsible experience in motion- 
picture photography and/or photographic 
laboratory work, involving essential opera- 
tion of film processing. $3410 yr. 



95 



Positions Wanted offered. References, resume, etc., avail- 
able on request. Write airmail to Stanley 

TV Cameraman-Director, year's experi- E . Lustberg, Jose Everisto Uriburu 1551, 

ence as cameraman, asst. stage manager Buenos Aires, Argentina, 
and lighting director; manager, small 

studio and director of 15-min fill-in TV Picture Optical Printer Available With 
shows, up to 5 shows weekly, mostly educa- Operator: Modern complete machine 
tional TV programs, also daily illustrated 35mm to 35mm and 16mm to 35mm 
newscast, at LR3 Radio Belgrano TV, using Acme Projector and Camera, regis- 
Buenos Aires, Argentina. Experienced in tration to 0.0001 in., including many 
still and live commercials. Born in U.S., accessories, synchronizers, etc. Over 200 
age 26, single, B.A. Hunter College (1951). TV commercials, many features and blow- 
Veteran, World War II. Desires position ups in color and B&W. Represents $20,000 
with TV station anywhere in U.S. or investment. Owner-operator has long 
Latin America; willing to travel. Fluent experience with Hollywood major studios. 
Spanish. Particularly interested in educa- Can double as cameraman. Reasonable, 
tional TV, nevertheless, will accept any Contact Wm. G. Heckler, 245 West 55 St., 
type of TV work related to experience New York, N.Y. Phone: Plaza 7-3868. 



Meetings 



WESCON (Western Electronic Show & Convention), Aug. 19-21, Civic Auditorium, 

San Francisco 

Biological Photographic Association, 23d Annual Meeting, Aug. 31-Sept. 3, Hotel Statler, 

Los Angeles, Calif. 

Illuminating Engineering Society, National Technical Conference, Sept. 14-18, Hotel 

Commodore, New York, N.Y. 

The Royal Photographic Society's Centenary, International Conference on the Science 
and Applications of Photography, Sept. 19-25, London, England 

National Electronics Conference, 9th Annual Conference, Sept. 28-30, Hotel Sherman, 

Chicago 

74th Semiannual Convention of the SMPTE, Oct. 5-9, Hotel Statler, New York. 
Audio Engineering Society, Fifth Annual Convention, Oct. 14-17, Hotel New Yorker, 

New York, N.Y. 

Theatre Equipment and Supply Manufacturers' Association Convention (in conjunction 

with Theatre Equipment Dealers' Association and Theatre Owners of America), 

Oct. 31-Nov. 4, Conrad Hilton Hotel, Chicago, 111. 

Theatre Owners of America, Annual Convention and Trade Show, Nov. 1-5, Chicago, 111. 
National Electrical Manufacturers Association, Nov. 9-12 Haddon Hall Hotel, Atlantic 

City, N.J. 

The American Society of Mechanical Engineers, Annual Meeting, Nov. 29-Dec. 4, 

Statler Hotel, N.Y. 

American Institute of Electrical Engineers, Winter General Meeting, Jan. 18-22, 1954, 

New York 

National Electrical Manufacturers Assn., Mar. 8-11, 1954, Edgewater Beach Hotel, 

Chicago, 111. 

75th Semiannual Convention of the SMPTE, May 3-7, 1954, Hotel Statler, Washington 
76th Semiannual Convention of the SMPTE, Oct. 18-22, 1954 (next year), Ambassador 

Hotel, Los Angeles 

77th Semiannual Convention of the SMPTE, Apr. 17-22, 1955, Drake Hotel, Chicago 
78th Semiannual Convention of the SMPTE, Oct. 3-7, 1955, Lake Placid Club, Essex 

County, N.Y. 

The Seventh Congress of the International Scientific Film Association will be held 
September 18-27 in the National Film Theatre and Royal Festival Hall, London S.E.I. 
A Scientific Film Festival will be held, and in addition, meetings will be held by the 
Permanent Committees on Medical, Research, Technical and Industrial Films. There 
will be special sessions on the technique and application of films in medicine. 

96 



Image Gradation, Graininess and Sharpness 
in Television and Motion-Picture Systems 

Part III: The Grain Structure of 
Television Images 

By OTTO H. SCHADE 
CONTENTS 

Symbols 98 

Summary 99 

A. Review of Principles 99 

B. Raster Processes 102 

1. The Raster Constant (n r ) 

2. Carrier Wave and Line Structure 

3. Response to Sine-Wave Test Patterns and Equivalent Passband 

4. Sine-Wave Spectrum and Equivalent Passband N e(t ) v for Random Deviations 

C. Electrical Constants and Apertures of Television Systems 115 

1. Frequency and Line Number 

2. Theoretical Passband and Aperture (6/) of Television Systems 

3. Horizontal Sine- Wave Response and Aperture Characteristics of Electro- 
Optical Systems 

(a) General Formulation 

(b) Apertures and Aperture Effects of Electrical Elements 

(c) Generalized Response and Aperture Characteristics 

4. Aperture Response of Camera Tubes and Kinescopes 

D. Equivalent Passbands and Signal-to-Deviation Ratios 139 

1 . General Formulation 

2. The Reference Values [R] m and N e(m ) 

3. Bandwidth Factors 

4. Signal-to-Noise Ratios in the Electrical System 

E. The Signal-to-Deviation Characteristic [R] g = f(B} of Television Picture 
Frames I 48 

1. Effect of Transfer Characteristics and Point Gamma on [/?,] 

2. Signal-to-Deviation Characteristics of Image Frames on the Kinescope Screen 
and at the Retina of the Eye 

3. Equivalent Passband (N e ()} and Sine- Wave Amplitudes 

4. Conclusions 

Presented by Otto H. Schade, Tube Dept., lished in this Journal in February 1951, pp. 

Radio Corporation of America, Harrison, 137-171; and Part II, "The grain struc- 

N.J., in part on October 15, 1951, at the cure of motion picture images an analysis 

Society's Convention at Hollywood, Calif., of deviations and fluctuations of the sample 

and on April 28, 1953, at the Society's number," in March 1952, pp. 181-222. 

Convention at Los Angeles. (This paper was received first on March 

Note: Part I of this paper, "Image struc- 3, 1953, and in revised form on June 5, 

ture and transfer characteristics," was pub- 1953.) 

August 1953 Journal of the SMPTE Vol. 61 97 



SYMBOLS 

Note: Peak values are designated by a peak sign over a symbol /; and average or mean 
values by a horizontal bar, n. When used with jY>values, the bar indicates the geo- 
metric mean for two coordinates. 



a Area of sampling aperture 

a e Equivalent sampling aperture 

A Frame area 

b Blanking factor (See Eqs. (61) and 

B Luminance 

c A constant 

C Capacitance 

d Viewing distance 

e Noise voltage 

EI Exposure (unit: meter candle sec- 
onds) 

E Signal voltage 

[E\ Rms noise voltage 

/ Frequency: f(x,y) a function of x 
and y 

A/ Theoretical rectangular frequency 
channel (Eq. (63)) 

A/ Noise-equivalent passband of electri- 
cal elements or systems 

h Horizontal dimension of equivalent 
sampling aperture or index for hori- 
zontal coordinate 

H Horizontal dimension of picture frame 

1 Noise current 

/ Intensity or current 

K A constant 

/ Unit of length 

m Horizontal bandwidth factor of elec- 
trical circuits (Eq. (79)) 

N Line number number of half- 
wavelengths of line- or sine-wave pat- 
terns per length unit 

N c Limiting resolution, N C (b) limiting 
resolution of aperture system follow- 
ing raster process 

N e Equivalent passband (Eqs. (22) to 
(28) Part II) 

N t Equivalent passband of an asym- 
metric aperture (Eq. (23) Part II) 

Ne(a) Equivalent passband of all apertures 
preceding and including analyzing 
aperture of raster process 

N e (b) Equivalent passband of all apertures 
following and including synthesizing 
aperture of raster process 

Ne(f) = (N C (h)n r }% Equivalent passband of 
theoretical television channel (Eq. 
(64)) 

Ne(m) = (N e (h)N e ( V ))? Equivalent optical 
passband of measuring aperture d m 

J?e(s) = (Ne(h)Ne(v)) s $ Equivalent optical 
passband of system between origin of 
deviations and point of observation 

n Number of particles or samples inside 
of sampling area 

n r Raster constant, number of points or 
lines in length unit 



q< 
Q f 



R 

[R] 



[R] 



[R] s 
s 

t 
J/ 

v 



V 

x,y 

Y 
a 



7 8 



Number of scanning lines including 
vertical blanking period (Eq. (62)) 
Electron charge 

Frame charge (Eq. (71 )) ,. 

Sine-wave response factor of an aper- 
ture (Eq. (18)) 

Electrical sine-wave response factor 
(Eq. (65)) 

Response factor of analyzing aperture 
(including preceding apertures) 
Response factor of synthesizing aper- 
ture (including following apertures) 
Rms response factor 
Resistance 

Signal-to-rms-deviation ratio, static 
value in a single image frame (Eq. 
(13) Part II) 

Reference signal-to-deviation ratio 
measured at the source with a known 
aperture d m 

Signal-to-deviation ratio of system 
Length of side of square aperture, or 
storage factor 
Time interval 
Frame time 

Vertical dimension of equivalent 
sampling aperture or index for verti- 
cal coordinate 
Vertical frame dimension 
Coordinates, x = coordinate in the 
direction of scanning 
Amplitude 

=(Ne(s)/Nc)h Horizontal bandwidth 
factor (Eq. (66)) 

=N e (s)v/n r Vertical bandwidth fac- 
tor (Eq. (67)) 

= (Ne(s)/(N e{h ) nr )\ Optical band- 
width factor (Eq. (68)) 
Constant gamma 

Point gamma, definition in Part I, p. 
145 

Point gamma of system at a particular 
signal level between origin of devia- 
tions and point of observation 
Characteristic aperture diameter 
Equivalent optical aperture of theo- 
retical television channel (Fig. 80)' 
Base of natural logarithm 
Transmittance 

Relative deviation ( Eqs. ( 1 3 ) to ( 1 7 ) 
Part II) 

Phase displacement between sample 
amplitude and crest intensity t N 
(Fig. 69) 
Flux 

Rms value of variational (a-c) flux 
(see Eq. (20)) 



98 



August 1953 Journal of the SMPTE Vol. 61 



SUMMARY OF PART III 



The analysis of grain structures in 
imaging systems containing a point- or 
line-raster process requires evaluation of 
the sine- wave response in two coordi- 
nates. The characteristics of the raster 
process are developed by a Fourier analy- 
sis of the optical image. The sine-wave 
response perpendicular to the raster lines 
(for example the vertical sine-wave re- 
sponse of a television system) is shown 
to contain in general a carrier wave, the 
normal aperture response to sine-wave 
test signals, and a series of sum-and- 
difference components with magnitudes 
depending on the aperture response 
products of the analyzing and synthesiz- 
ing apertures preceding and following the 
raster process (camera tube and kine- 
scope in television systems). A graphic 
representation of the raster equation 
(Fig. 70) shows at a glance the number 
and magnitude of the sine-wave compo- 
nents for any combination of apertures 
used with the raster process. The appli- 
cation of the aperture theory developed 
in Part II yields an equivalent optical 
aperture (Fig. 80) and equivalent pass- 
band (Eq. (64)) for the theoretical tele- 
vision channel. The evaluation of the 
horizontal sine-wave response of electro- 
optical systems containing electrical and 
optical elements is simplified by estab- 
lishing normalized characteristics for the 
sine-wave response, equivalent pass- 
band, aperture cross section, and edge 
transition of a variety of electrical re- 
sponse characteristics (including aper- 
ture correction) in cascade with optical 
apertures. Because of their general 
character and use in the evaluation and 



design of television systems, the range of 
parameters has been extended beyond the 
cases used in examples. 

In normalized units equivalent pass- 
bands (horizontal and vertical) of elec- 
trooptical systems are specified by band- 
width factors (or and /3), which are ratios 
of the equivalent passband of the system 
to the theoretical passbands N e ( k ) and n r 
of the television channel (section Z)i). 
These bandwidth factors emerge as sig- 
nificant parameters specifying the charac- 
teristics of the system. 

The translation of electrical noise 
levels into optical deviations in a tele- 
vision frame is now readily accom- 
plished, permitting evaluation of granu- 
larity by the methods discussed in Part II. 
It is shown that the electrical signal-to- 
noise ratios usually quoted for television 
systems have by themselves little meaning 
when television grain structures are com- 
pared, because the transfer characteris- 
tics and apertures of the system cause 
pronounced changes in signal-to-devia- 
tion ratios and the amplitude of the 
sine-wave components contained in opti- 
cal deviations of a television picture 
frame. It is concluded that an adequate 
description of granularity in television 
and motion-picture frames requires speci- 
fication of the sine-wave spectrum and 
signal-to-deviation ratio in the retinal 
image as a function of luminance and for 
a specified viewing distance. An assess- 
ment of the perception of deviations 
throughout the luminance range of 
motion pictures and television images 
can be made by introducing the char- 
acteristic of threshold signal-to-deviation 
ratios as a reference level. 



A. REVIEW OF PRINCIPLES 



The principles and method developed 
in the analysis of motion-picture granu- 
larity in Part II of this paper can be ap- 
plied to all imaging systems and will be 
summarized briefly. Random fluctua- 



tions of luminance in motion-picture or 
television images cause the appearance 
of a moving granular structure. In a 
single picture frame representing a con- 
stant light level the structure is stationary 



Otto H. Schade: Television Grain Structure 



99 





H _ 




-tt- - 



i a 



L 

1J 










It 



-il- 






100 



August 1953 Journal of the SMPTE Vol. 61 



and the luminance variations are static 
deviations from the average luminance 
which is the optical signal. 

Optical signals and deviations are 
measured by taking samples of the image 
flux with an aperture. The average 
value of the sample readings is the signal. 
The relative magnitude of the deviations 
is expressed by the relative deviation <r or 
its reciprocal, the signal-to-rms deviation 
ratio [R]. When the deviations are ran- 
dom (see Part II for definition) the value 
[R] measured at the source of deviations 
is directly proportional to the one-half 
power of the effective area a e of the 
sampling aperture as stated by 

[R] - \/<r - (a,*.)! 

where j? specifies the mean "particle" 
density in the random structure at the 
source. The effective sampling area of 
practical image-forming devices or sys- 
tems can be determined from the geom- 
etry of their point image (see Part II) or 
from the total sine-wave energy response 
of the point image, obtained by a Fourier 
analysis of a test image such as a single 
sharp line, a single-edge transition, a 
random grain structure, or from sine- 
wave test patterns. The last two meth- 
ods mentioned, particularly the method 
using sine-wave test patterns with vari- 
able line number, are known from anal- 
ogous electrical measurements to be most 
accurate because of the high energy level 
of the observed signals and the simplicity 
of evaluation. In sine-wave response 
measurements the point image is re- 
garded as an "aperture" of unknown 
geometry which is made to scan a series 
of constant-energy sine-wave test pat- 
terns. The total relative sine-wave 
energy of the aperture response charac- 
teristic is specified by a single number 
N e interpreted as an equivalent passband. 
The reciprocal of this measure K/N t 
specifies the diameter of the desired 
equivalent sampling aperture (see Table VII, 
Part II). The point images of practical 
devices are often asymmetric. In this 
case the equivalent sampling aperture 



can be specified as a rectangle with the 
dimensions h and y, which are the re- 
ciprocals of two equivalents: 

a, - hv - [Ne w Ne (v) \ ~ l (51) 

The asymmetric point image is described 
by two sine-wave response characteristics 
in rectangular coordinates (//and V} and 
their corresponding equivalent pass- 
bands N e(k) and N. M . 

The signal-to-deviation ratio [R] can 
now be stated in the forms 



[R] - 



[R] 



(52) 



where N t is the geometric mean of the 
two equivalent passbands. 

The particle density n at the source can 
be determined by a count of the number 
of particles (grains or electrons) in a unit 
area of the random structure in which 
the deviations originate. When this is 
impractical, n is obtained from a refer- 
ence value [R] m measured or computed 
with an aperture of known area a m or 
equivalent passband J7,< M ). 

The actual signal-to-deviation ratio 
[R] s at any one point in the imaging sys- 
tem can then be computed accurately 
from the aperture ratio (Eq. (37) in Part 
II) which, stated in terms of N e - values, 
has the form 



. (53) 



[R], = 



where 

[R] m = signal-to-deviation ratio at the 
origin of deviations, measured with an 
aperture of equivalent passband tf,( m ) 

jfc(m) = (New A^rOm* = equivalent op- 
tical passband of measuring aperture 

f?W = (Ne(h)Ne(r))J = equivalent op- 
tical passband of system aperture 
between origin of deviations and point 
of observation 

7, = overall transfer ratio or "point 
gamma" of system elements at the 
particular signal intensity between 
origin of deviations and point of ob- 
servation. 

The analysis of optical deviations in tele- 
vision images requires a translation of 



Otto H. Schade: Television Grain Structure 



101 



television system parameters and charac- 
teristics into equivalent optical units. A 
schematic representation of a television 
process is shown in Fig. 65. The light 
flux in the optical image A Q formed by 
the camera lens is transduced into an 
electrical image A\ in the television 
camera tube. The charge image A\ is 
scanned by an aperture 5i along a sys- 
tem of parallel lines termed a line raster. 
The aperture 5i is the electron beam of 
the camera tube which transduces the 
electrical aperture flux into video signals. 
The electrical signals are amplified, lim- 
ited by electrical filters, transmitted and 
again transduced into light-flux varia- 
tions by the aperture dz of an electro- 
optical transducer (kinescope) scanning 
the frame area A 2 . The two scanning 
apertures 5i and 5 2 are moved with uni- 
form velocity and in synchronism over the 
respective frame areas. Like optical 
apertures, these scanning apertures have 
two dimensions, and their response is 
readily described by normal sine-wave 
response characteristics and equivalent 
passbands. New elements in the imag- 
ing system requiring evaluation in terms 
of optical response characteristics are the 



line raster and the electrical system of 
amplifiers and low-pass filters. 

Luminance deviations in a television 
frame may be caused by a number of 
sources located at different points in the 
system (see Fig. 65). When the devia- 
tions originate in a preceding photo- 
graphic process, the television system is 
an aperture process transferring a two- 
dimensional granular structure. Devia- 
tions originating in electrical elements, 
however, may not be associated with the 
transferred image. Electron sources such 
as the cathodes of electron guns or ampli- 
fier tubes continually produce random 
fluctuations in the flow of electrons, 
which are arranged and displayed arti- 
ficially in two dimensions by the scan- 
ning process. The resulting luminance 
deviations in the frame area may, how- 
ever, be regarded as the image of a ran- 
dom particle structure scanned with a 
hypothetical camera and measured with 
a theoretical sampling aperture 6(/> 
which will be found to have a specific 
value given by the system constants. 
With this concept all cases can be treated 
by one method. 



B. RASTER PROCESSES 



1. The Raster Constant (n r ) 

The formation of images by lenses or 
optical systems is continuous in both 
coordinates of the image area. It is, 
therefore, permissible to determine sig- 
nals and deviations from a limited num- 
ber of sample readings, because every 
point in the image area undergoes an 
aperture process. The aperture shape 
becomes indistinguishable in areas of 
constant luminance. In the presence of 
deviations, the steady "signal" flux can 
be considered as a "carrier" flux of con- 
stant intensity 7 "modulated" by ran- 
dom deviations. 

Printing, facsimile and television are 
sampling processes in which the number 



of aperture positions is finite in one or 
both coordinates of the image frame. 
The image flux is no longer continuous 
in two coordinates but contains periodic 
components. An arrangement limiting 
aperture positions to a fixed number of 
uniformly spaced points in the image 
frame is termed a point raster; an arrange- 
ment providing continuous aperture 
positions along uniformly spaced parallel 
lines is termed a line raster. The "raster 19 
constant n r specifies the number of aperture 
positions in the length unit of a geometric 
arrangement of points or lines; it does not 
specify the dimensions of the "points" 
or "lines" themselves which are deter- 
mined by the geometry of the sampling 
apertures used with the raster process. 



102 



August 1953 Journal of the SMPTE Vol. 61 






Fig. 66. Intensity distribution and "carrier" waves in the >-coordinate of line- rasters. 



2. Carrier Wave and Line Structure 

A line raster limits the number of aper- 
ture positions perpendicular to the raster 
lines. Areas of constant luminance are 
reproduced by the aperture 5 2 as a flux 
pattern in which the intensity is constant 
in the direction x parallel to the raster 
lines but contains a more or less pro- 
nounced periodic component in the y- 
coordinate defined as the coordinate 
perpendicular to the raster lines (Fig. 66). 
The following analysis of conditions in 
the ^-coordinate of a line raster applies 
to optical as well as television processes f 
and also to point rasters which cause 
periodic components in both x- and y- 
coordinates. (In television images the 
coordinate Y is identical with the vertical 
coordinate V of the image frame.) 

The periodic component can be re- 
garded as a constant carrier wave added 
by the raster to the continuous carrier 
flux of a normal aperture process. The 
signal flux from the analyzing aperture 
5i determines the average intensity level 
7, i.e., the scale factor of the image flux. 
It is seen by inspection of Fig. 66 that 
the length of the carrier wave is the re- 
ciprocal of the raster constant: Ay = 



l/r, while waveform and relative ampli- 
tude of the carrier wave are determined 
by the geometry of the synthesizing aper- 
ture dz- 

A Fourier analysis of this "pulse car- 
rier wave" shows that the intensity dis- 
tribution I( y ) = f(y] contains the constant 
signal term 7 and a series of harmonic 
cosine waves : 

I v = 7[1 + 22r^ (pnr) axpwynr] (54) 

(p = 2,4,6,.. .) 

The cosine terms specify the harmonic 
components of the carrier wave, which 
have (television) line numbers N r \ = 
2n r , Nri = 4n r , N ri = 6n r , ---- Their 
relative intensities are specified by coef- 
ficients which are the sine-wave response 
factors r$(. . .> in the ^-coordinate of the 
particular aperture ^2 at the line num- 
bers of corresponding carrier harmonics. 
The cosine-wave components are in 
phase at the aperture center (on the 
raster line) when the aperture has axial 
symmetry! and its response decreases 
asymptotically to zero. When the re- 
sponse characteristic has an oscillatory 
form (compare Figs. 41 and 42 of Part 
II), the phase may reverse at each zero re- 



t A two-dimensional Fourier analysis of the 
television picture was presented in an early 
paper by Mertz and Gray. 1 



t Apertures with asymmetric cross sections 
introduce phase shifts between cosine terms 
and will be discussed in Part IV. 



Otto H. Schade: Television Grain Structure 



103 



.08 



.04 



n r =400 

2I> =0.1 

*(2_n r ) 

*(Y)=*CH-O.II6 


6 (see fiq. 97) ill 

COS(ir800Y)] :: 











800 



4/ 



800 



DISTANCE 



Fig. 67. Intensity distribution in v- 
coordinate of raster process with kine- 
scope aperture 5 2 >l/r passing only 
one cosine term of the carrier wave. 



sponse point. Examples illustrating a 
numerical synthesis of the intensity dis- 
tribution expressed by Eq. (54) are 
shown in Figs. 67 and 68. Equation (54) 
establishes a direct relation between the 
geometry of the line image and the sine- 
wave response characteristic of the line- 
generating point image. For the purpose 
of reconstructing an aperture cross sec- 
tion (i.e. an isolated line) from its sine- 
wave spectrum the fundamental com- 
ponent Nri = 2n r in Eq. (54) is given a 
low value for which the bracketed terms 
of Eq. (54) equal zero at the distance 
y = ^n r . This condition is obtained 
when 



(55) 

A fundamental component N T = 2n r = 
200 lines was used for the aperture syn- 
thesis (Fig. 68) from the sine-wave 
response characteristic (Fig. 95). 

The presence of a pronounced line 
structure in the image is highly undesir- 
able. Perfect continuity is restored when 
none of the carrier-wave components are 
reproduced by the aperture 5 2 , i.e., when 



the aperture response is zero at line num- 
bers which are integral multiples of 2n r . 
Practical imaging devices usually have 
an aperiodic response characteristic. 
In some cases the response has non- 
integral zeros, but the response is usually 
low beyond the first zero. A substan- 
tially continuous or "flat" field is, there- 
fore, obtained when 



0.005 



(56) 



This response factor causes a ripple 
amplitude of 1%, i.e., a peak-to-peak 
intensity variation of 2%. The aperture 
process dz in the reproducing device 
(kinescope) is followed by other imaging 
processes, for example by the process of 
vision or by a photographic process. It 
is, therefore, unnecessary to restrict the 
response of the aperture 2 alone by Eq. 
(56) but rather the overall sine-wave 
response r$b of the aperture system fol- 
lowing the raster process (indicated by 
the index ). 

The flat-field condition specified by 
Eq. (56) may be stated in the form 



N e 



(6) 



2n r 



(56a) 



Assume for example that a standard 35- 
mm motion-picture process (Table IX 
(1 to 4), Part II) which has a limiting 
resolution N c of approximately 1100 
lines, is used for video recording. It 
follows from Eq. (56a) that a standard 
525-line television raster which contains 
n r = 490 active line traces is just resolved 
in the optical projection of the 35mm 
print. Even with a kinescope having 
3000-line resolution and an aperture 
response r^ (27lr ) = 0.62 which causes a 
pronounced line structure on the kine- 
scope screen, the response in the optical 
35mm projection is only 1% at N = 2n r .f 
The carrier "ripple" has then an ampli- 
tude of 2% and a peak-to-peak amplitude 
of 4%. 



f Failure to interlace perfectly will intro- 
duce carrier components at one-half the 
line number, for which the overall response 

is 22%. 



104 



August 1953 Journal of the SMPTE Vol. 61 



HIGH -DEFINITION IMAGE ORTHICON 
LENGTH UNIT: v = V=l.7" 




.00 1 .002 .003 .004 JOO5 

DISTANCE (Y) 



Fig. 68. Synthesis of line cross section formed by a camera-tube 
scanning beam for the condition 5^ l/ r (nonoverlapping). 



'/2N -1 



3,+ 

RASTER 




Fig. 69. Sampling and re- 
production of sine-wave test 
pattern in the ^-coordinate 
by a raster process and de- 
velopment of raster equa- 
tion by regarding "modu- 
lated" carrier wave as the 
sum of interlaced carrier 
waves with different ampli- 
tudes. 



Otto H. Schade: Television Grain Structure 



105 



3. Response to Sine-Wave Test Patterns 
and Equivalent Passband 

A line raster has no effect on the sine- 
wave response of the apertures Si, and 5 2 
in the x-coordinate (parallel to the raster 
lines), in which the aperture process is 
continuous. The discrete aperture posi- 
tions in the ^-coordinate affect the re- 
sponse of the two apertures in a different 
manner. 

The analyzing aperture di "samples" 
the flux of a test pattern in thejy-direction 
at the raster points only, all other aper- 
ture positions are "blocked" by the 
raster. What is left of the normally con- 
tinuous aperture signal is a series of exact 
samples of its response at regularly 
spaced distances Ay = \/n r as indicated 
by Fig. 69a. The reader may visualize 
the raster as an opaque plate with very 
fine slits (holes for a point raster) 
through which he, or a photoelectric 
device, views the test pattern from a 
fixed distance. He can control 5i by 
varying the spacing between the raster 
plate and the test object. When the test 
pattern line number N is varied, the 
sample amplitudes vary in direct propor- 
tion to the normal sine-wave response of 
8 1. A further interpretation of these 
amplitudes cannot be given without con- 
sidering the synthesizing aperture proc- 
ess. 

For a linear system, the intensity of the 
light flux from the synthesizing aperture 
5 2 is proportional to the signal amplitude 
delivered by 5i at corresponding raster 
points. The reproduced waveform, 
however, is only an artificial approxima- 
tion of the test pattern wave, determined 
by the raster constant and the geometry 
of the aperture 5 2 as illustrated in Fig. 
69b. The fundamental sine-wave re- 
sponse and the waveform distortion can 
be evaluated by a Fourier analysis. For 
this purpose the periodic wave may be 
regarded as the sum of a series of inter- 
laced carrier waves, each having a con- 
stant amplitude and a wavelength \/n r ' 
which is longer than the normal raster 



period (see Fig. 69c). These component 
carrier waves are displaced in phase by 
distances \/n r , 2/n r etc., with respect to 
one another and can be expressed by 
Fourier series (Eq. (54)) differing only 
in amplitude and phase of the terms. A 
vectorial addition of corresponding terms 
yields an expression for the waveform. 
For the conditions that the average in- 
tensity 7 2 in the image of the test pattern 
has the same numerical value as the test 
pattern intensity 7, and the transfer ratio 
of signals (gamma) is unity, the expres- 
sion obtained for the intensity 7( y) 2 = 
/(>>) is the following Eq. (57) : 
7 (tf)2 = 7[1 + S2r0 (jmr) coap*yn r ] (C) 

+ iNffirfr cos [(NMirynr + 9} (N) 
cos [(/> + 

8] (S) 



where N/n r ^yn r -e] (D) 

p = 2, 4, 6, ... 

n r = Raster constant (number of sam- 
pling positions per length unit) 
y Distance along j-coordinate (same 

length units as l/n r ) 
I = Average intensity in ^-coordinate 
fff = Crest intensity of sine-wave flux in 

test pattern 
r$i = Response factor of aperture di at 

the line number N 
r$ 2 = Response factor of aperture 62 at 

the line number N 

r ^(index) = Response factor of aperture 5 2 

at line number indicated by index 

6 = Phase displacement between 

sample amplitude and crest IN 

(Fig. 69). 

The terms of Eq. (57) have been 
arranged in four products. The first 
product (C) contains only the steady 
carrier components as expressed by Eq. (54). 
The magnitude and numbers of the sine- 
wave terms depend on the aperture re- 
sponse of d 2 only. The second product 
(N) is identified as the normal sine-wave 
signal flux $\i of the cascaded aperture 5i 
and 5 2 at the line number N. The third 
and fourth products (S) and (D) are har- 
monic components with line numbers 
which are the sums and differences of the 



106 



August 1953 Journal of the SMPTE Vol. 61 



1? 

i 3 

u <n 

Is 




I 

M 



Cl 



srrr 




2 4 

LINE NUMBER (N/n r ), OF SINE -WAVE INPUT 




i.O O5 

RESPONSE 
FACTOR (r^ ) 



LINE NUMBER CN/n r ) 
Fig. 70. Conversion characteristic of raster (Eq. (57)). 




LINE NUMBER N/n r OF OUTPUT SIGNALS 
S\ 2 3 4 5 6 7 

03 6 5 4 3 2 I 

D 2 4 3 2 I I 

D| 2 I I 2 3 

NO I 2 3 4 5 




12345 

LINE NUMBER (N/n r ), OF SIGNAL INPUT 

Fig. 71. Graphic representation of the combined sine-wave response of raster and 
synthesizing aperture 5 2 by normal aperture characteristic and "sidebands." 



carrier components 2n r , 4n r etc., and the on the sine-wave response of the apertures 

"modulating" sine-wave signal A^. Their 61 and 5 2 . The sine-wave response charac- 

magnitude and number depend on the teristic of the raster itself can be repre- 

response of both apertures d\ and 6 2 . sented graphically by a conversion char- 

The raster process introduces addi- acteristic (Fig. 70) with constant re- 

tional sine-wave components depending sponse factors r r = \ for all variable 



Otto H. Schade: Television Grain Structure 



107 




o 
o 
in 



o 
o 




o 
o 

fO 



o 
o 
<M 



4, 

8 8 

II 



-I 

i 





S-.1 
.2 S 



a, js 



T5 



U 



108 



August 1953 Journal of the SMPTE Vol. 61 



Table XV. Sine- Wave Components (N/n r )* and Response 
Factors (rj) for (N/n r \ - 1.6. 



Component : 



N 



Line Number (N/n r ) 


0. 


4 


1 


.6 


2 




2 


4 


3.6 


4 




Response Factor rfa 





675 





.675 





.675 





.675 


0.675 


0. 


675 


Response Factor rfo 


o 


.92 





.39 


2X0 


.25 





.14 


0.0 


0. 






Overall Response Factor r$ v . 62 . 263 



0.338 0.945 0.0 0.0 



terms and the response r r 2 for the 
constant carrier components. The car- 
rier components are represented by an 
infinite number of horizontal lines C\, Ca 
etc., because their existence is independ- 
ent of the sine-wave signal input. The 
line number of the normal sine-wave 
components (line TV) and the sum and 
difference terms (lines Si, 2, 3 . . . . and 
DI, D<>, DZ ....), however, vary with the 
line number (N/n r )\ of the input-signal 
as shown by the network of diagonal 
raster characteristics. The raster charac- 
teristic (Fig. 70) is a graphic representation 
of Eq. (57). The use of the diagram is 
simple. A vertical projection of the 
input line number (N/n r )i locates the 
output signal components at the inter- 
sections with the raster characteristics as 
illustrated for (N/n r )i = 1.6. The rela- 
tive intensity of the sine-wave components is the 
product of the aperture response factor 
ri, at the line number of the input-signal 
and the response factor rfo at the line 
number of the output-signal component. 
The sine-wave response characteristic of 
the "analyzing" aperture Si is, therefore, 
drawn in Fig. 70 under the input coordi- 
nate of the raster characteristic, and the 
sine-wave response characteristic of the 
"synthesizing" aperture 6 2 is drawn with 
its line-number scale parallel to the out- 
put coordinate (both line-number scales 
must be in relative units N/n r ). The 
sine-wave response factors of the example 
are listed in Table XV for (N/nr) i = 1.6. 
To evaluate the total sine-wave spec- 
trum of a raster process it is expedient to 
combine the raster response r r with the 
response characteristic rfo = rjtffa . . . rf n 



of succeeding apertures into one charac- 
teristic. The characteristic Fig. 71 repre- 
sents the overall sine-wave response rj r b 
for constant amplitude sine- wave signals 
of the raster and a particular aperture 
process (5&) following the raster. Ap- 
propriate scales permit a direct reading 
of the line number and response factor 
rf b of all associated terms in the y- 
coordinate of the final image. The re- 
sponse factor (2r$) of the single constant 
carrier term Ci is indicated. The normal 
response characteristic (A^) of the aper- 
ture 5b appears symmetrically repeated f 
at each carrier line number 2n r , 4n r etc. 
The response pattern between N/n r 
and 1 repeats indefinitely. A large aper- 
ture for example has zero response at 
N/n r < 1 ; its response nevertheless re- 
peats up to infinity, periodically going to 
zero. 

The fact that the passband of an aper- 
ture 5b is repeated by addition of a raster 
process, is demonstrated by Figs. 72a to 
72d. Figure 72a is a photograph of a 
test pattern having a variable line num- 
ber. 2 A sharp photograph (5& small) of 
the pattern through a raster plate having 
very fine lines (d a small) is shown in 
Fig. 72b. A photograph made with a 
larger aperture 5 b giving a flat field is 
shown in Fig. 72c which may be com- 
pared with the image Fig. 72d made 
without raster and the same aperture S&. 
In all practical cases the infinitely repeti- 
tive spectrum of the response r$ r \> is lim- 
ited by the finite response r$ a of apertures 
preceding the raster, because the overall 

t Electrically known as "sidebands." 



Otto H. Schade: Television Grain Structure 



109 



0.5 



APERTURE CHARACTERISTICS: 



CURVE 1:N e /n r = 1.0 

2: N e /n r = 0.667 

!-4 









0.5 1.0 1.5 2.0 

RELATIVE LINE NUMBER (N/Tlp) 

Fig. 73. Construction of repetitive spec- 
trum by "folding" of response charac- 
teristic. 

response of the entire imaging system 
r $(v) ~ rtaTtbrr becomes zero when the 
response factor r$ a is zero. 

4. Sine- Wave Spectrum and Equivalent 
Passband N e ( s ) y for Random Deviations 

For the analysis of deviations it is un- 
necessary to examine the waveform and 
phase distortion caused by the raster (to 
be discussed in Part IV of this paper), 
because the distribution of sine-wave 
components in a source of deviations is 
random. The sine-wave spectrum for 
deviations is, hence, obtained by arrang- 
ing all sine-wave components in order 
of their line number, combining re- 
sponse factors at equal line numbers by a 
quadrature addition (square root of the 
sum of the squares). This process has 
been carried out for a variety of aperture 
combinations d a and 8b having exponen- 
tial cross sections T = e~ (r/r )2 and a 
sine-wave response r$ = e -(- 627 tf/Ar e > 2 (Fig. 
44, Part II) which is a satisfactory equiva- 
lent for optical processes. The repetitive 
section of raster and aperture response 
characteristic r$ r i> can be constructed 



by "folding" the normal response char- 
acteristic into the range N/n r to 1 
as illustrated in Fig. 73 for two aperture 
sizes N e /n r = \ and N e /n r = 0.667. 

Overall sine-wave spectra computed for 
various combinations of aperture sizes 
are shown in Figs. 74a to 74c. When 
both apertures 5 and 5& are large, i.e., 
when N e is smaller than the raster con- 
stant (N e /n r = 0.5 in Fig. 74a), the sine- 
wave spectrum is substantially the same 
as without raster; when N e (b) is increased, 
the high-"frequency" components in- 
crease considerably faster than without 
raster and show periodic maxima and 
minima. These variations decrease when 
N e ( a ) is increased (Fig. 74b), and dis- 
appear substantially for values N e ( a ) = 1 
(Fig. 74c). It is concluded that the addi- 
tion of a raster process may increase the 
normal sine-wave response and extend 
the aperture passband to higher line 
numbers even for the "flat-field" condi- 
tion N e(a) = N eW = 0.67 n r (Fig. 74b). 
The raster can, therefore, have a sub- 
stantial negative aperture effect which in- 
creases the intensity and edge sharpness 
of the reproduced grain structure in the 
^-coordinate. 

The equivalent passband N e ( S ) of the 
raster process is the integral of squared re- 
sponse factors (Eq. (28), Part II) deter- 
mined from the total sine-wave response 
of the system. The computation of the 
integral for various aperture combina- 
tions can be simplified by calculating the 
rms response of 5& for the repetitive section 
N/n r = to 1 . The rms response factor 
[r$ ] b at each input line number (Fig. 75) 
is obtained by a quadrature addition of 
associated sine-wave components (shown 
in Fig. 73). Because this response is 
repetitive, the integral 



can be evaluated within the limits N/n r 
= and 1 from 



(58) 

where [r$] a is the rms value of response 
factors of d a , coordinated by folding the 



110 



August 1953 Journal of the SMPTE Vol. 61 



WITH RASTER 

WITHOUT RASTER 



CURVE Ne(a)A>r N e (b)/nr 

1 0.67 0.67 

2 0.67 1.0 

3 0.67 2.0 
WITH RASTER 

WITHOUT RASTER 



Ne(a)/nr 
I .0 
1.0 



WITH RASTER 

WITHOUT RASTER 




I 2 3 

RELATIVE LINE NUMBER (N/n r ) 

Fig. 74. Overall sine-wave spectra of raster processes for various 
aperture sizes 8 a and 5&. 



response characteristic r$ a into the limits 
N/n T = to 1. The values [rf] a and 
[rf]b are identical when 6 = S&. The 
products of various aperture combina- 
tions are, thus, easily computed from 
Fig. 75. The equivalent passbands 
Ne(*)* of the system are plotted in Fig. 76 
as a function of the passband N e ( a )/n r of 



the analyzing aperture 5 with N e( b)/n r 
as a parameter. Examination of these 
functions reveals the following facts. 

(a) When both N e (a) and N e (b) are smaller 
than 0.7n r the aperture flux at successive 
raster points is correlated sufficiently 
(overlapping) to eliminate the effect of 
the raster. The equivalent passband 



Otto H. Schade: Television Grain Structure 



111 



I.S 



E FAC 
- 
6 



RMS SINE-WAVE RES 

u> 



APERTURE CHARACTERISTICS: 



)2 . r~ =e-(- 627N / N e> a 






2.0 



0.66 



0.33 



0.5 1.0 1.5 2.0 

RELATIVE LINE NUMBER (N/n r ) 

Fig. 75. Rms response of apertures 
and raster to sine-wave signals. 



New* of the process can then be com- 
puted from the normal aperture response 
without raster or may be approximated 
with good accuracy by the cascade for- 
mula: 



(59) 



(ft) When one or both values N e ( a) or 
N e (b) are greater than n r , the aperture flux 
is no longer correlated by at least one 
aperture, and the equivalent passband 



of the process can be computed with good 
accuracy from the product. 



=* (N e(a) N e(b ))/n r 



(60) 



(c) For all other values the aperture flux 
is partially correlated and the value 
N e (s)v should be computed as outlined 
above or may be approximated by the 
values computed for exponential aperture 
characteristics (Fig. 76). It should be 
mentioned that a square aperture pre- 
sents a special case because of its strongly 
periodic aperture response and large 
number of terms which cause periodic 
deviations from the characteristics shown 
in Fig. 76. The square aperture is of 
interest as a mathematical equivalent, 
but its characteristics are in many cases 
undesirable for practical processes. The 
greatly enlarged reproduction of a photo- 
graphic grain structure by point- and 
line-raster processes is illustrated in Fig. 
77. The original grain structure is shown 
in Fig. 77a. The samples "seen" 
through a fine point raster plate (d a 
small) are shown in Fig. 77b; their re- 
production by a square aperture provid- 
ing a "flat" field is shown in Fig. 77c. 
Reproduction of the same grain structure 
by a line-raster process using a square 
reproducing aperture is shown in Figs. 
77d and e. The higher horizontal defi- 
nition obtained with a vertical slit aper- 
ture is illustrated by Fig. 77f. 

A comparison of a line-raster process 
(a) using a round cos 2 aperture db with 
a continuous process (b) using the same 
apertures is shown with a lower mag- 
nification in Fig. 78. The slight in- 
crease in vertical sharpness by the raster 
process (a) observed in the originals will 
probably be lost in the printing process. 



112 



August 1953 Journal of the SMPTE Vol. 61 



2.5S 



ROUND APERTURES T=-((/ r o) 2 




0.5 IX) 1.5 

RELATIVE PASSBAND OF ANALYZING APERTURE N e (Q)/n r 



2.0 



Fig. 76. Equivalent relative passband (0) of systems containing a raster process 
as a function of the relative passband #<)// of the analyzing aperture 5 a for various 
relative passbands N e(b )/n r of the synthesizing aperture 3&. 



Otto H. Schade: Television Grain Structure 



113 




Fig. 77. Reproduction of photographic grain structure by point- and line-raster 
processes with rectangular apertures (highly magnified). 



114 



August 1953 Journal of the SMPTE Vol. 61 




Fig. 78. Grain structure reproduced (a, at left) with, and (b, at right) with- 
out line-raster process by a round cos 2 aperture. 



NOTE: Figures 85 and 109 now follow on this coated paper insert. Figures 79, etc., 
are arranged below as best possible for nearness to pertinent text. 



C. ELECTRICAL CONSTANTS AND APERTURES 
OF TELEVISION SYSTEMS 



1. Frequency and Line Number 

The transmission of two-dimensional 
images over an electrical frequency chan- 
nel is based on a conversion of lengths 
into units of time. To effect this conver- 
sion, television systems make use of a 
horizontal-line raster scanned by a 
single aperture. The signals of all aper- 
ture positions in the raster are trans- 
mitted in sequence because of a time- 
proportional displacement of the aper- 
ture along the raster lines. The correla- 
tion of length and time units depend 
obviously on the dimensions of the raster, 
the order in which the raster lines are 
scanned, and the time T/ assigned for 



the transmission of one picture frame. 
The principal relations are illustrated in 
Fig. 79 for a raster constant n r = 12 and 
the normal frame aspect ratio H/V = 
4/3. A time allowance must be made for 
synchronizing signals and the finite re- 
turn periods of the scanning apertures. 
These time percentages are the "blank- 
ing" periods tb v and t bh in Figs. 79b and c 
which correspond to the blanking mar- 
gins b h and b v in Fig. 79a. 

The length unit / is the vertical frame 
dimension V, as indicated in Fig. 79a. 
In the vertical coordinate the length / or 
any subdivision down to A/ = \/N, = 
\/n r corresponds to relatively long time 
intervals, i.e., low electrical frequencies. 



Otto H. Schade: Television Grain Structure 



115 




Fig. 85a. Composite print made by a photographic synthesis (Fig. 84). 



JOO 




Fig. 85b. Enlarged section of Fig. 85a showing edge "transients" in two coordinates. 
116 August 1953 Journal of the SMPTE Vol. 61 



\ 




Fig. 85c. Addition of optical line-raster process to Fig. 85b. 



A test pattern with N v = 2 (right side of 
Fig. 79a) filling the entire frame area 
generates the video signal illustrated in 
Fig. 79b. The electrical frequencies / 
required for the reproduction of vertical 
sine-wave samples N v are determined by 
the raster constant n r . The highest elec- 
trical frequency / max is generated when 
the signal amplitudes in successively traced] 
raster lines alternate between two values. 
One period is, therefore, completed in the 
time 2t h = 2T f /n s (see Fig. 79b). 

In all properly operating television 



t It is noted that successively traced raster 
lines in a 2 to 1 interlaced raster are either 
the even or the odd numbered raster lines 
which correspond to a test pattern line 
number n r /2. Without interlacing, the 
frequency / max has the same value but 
the test pattern line number producing it is 
equal to n r . With 2 to 1 interlace, a line 
number equal to n r causes constant ampli- 
tude signals in one complete field and con- 
stant signals of different amplitude in the 
following field. 



systems the electrical sine-wave response 
is unity and is without phase error from 
the frame frequency (1/7/) on upwards 
to far beyond the frequencies occurring 
in the reproduction of vertical sine-wave 
samples. The sine-wave response, there- 
fore, does not enter as a factor limiting 
the vertical sine-wave response of the 
television system. The vertical response of 
the television system is determined entirely 
by the raster constant n r and the two- 
dimensional system apertures as de- 
scribed in the preceding section. 

In the horizontal coordinate the length 
unit / = V = 3/4H (see Fig. 79c) and 
the length of half-waves l/N h in a sine- 
wave test pattern are scanned in very 
short time intervals t\ k corresponding to 
high electrical frequencies. The spatial 
frequency of the optical test pattern 
wave has the value 0.5AV/. The hori- 
zontal time unit is three fourths of the 
active line time, and the electrical fre- 
quency corresponding to a line number 
X h is therefore : 



Otto H. Schade: Television Grain Structure 



117 



AI : 



BI : 




B2 



B3 



where 



f h = 0.5c N h n r /Tf cycles /sec (61) 

= Frame time in seconds (-g- 1 ^- sec in 
standard television system) 

= Number of active raster lines in 
frame area 

= Horizontal line number 

= (H/V}/(\ - b h }(\ - M; the 



standard value is c = 

(0.84 X 0.935) = 1.7 
The total number of scanning lines in- 
cluding the inactive lines in the blanking 
margin b v is usually stated as the scan- 
ning line number of the system, which is 
n s = n r /(\ - b v ) = 1.07 n r (62) 



118 



August 1953 Journal of the SMPTE Vol. 61 





Fig. 109, Al-3 and Bl-3 at left, and 
Cl and C2 above. Grain structures of 
television and motion-picture processes. 



2. Theoretical Passband and Aperture 
(df) of Television Systems 

The video frequency channel of the 
television system is determined by the 
frame time T/, the raster constant n r , and 
the desired horizontal cutoff resolution 
N c(h ) of the system ; it is given for normal 



blanking percentages by the relation 

A/ = 0.85 N e( H)n r /Tf cycles/sec (63) 

The product (A^Ajflr) corresponds to the 
square of the equivalent passband ft? = 
(N t( h)N,( V )) of an optical aperture. The 
relation between the theoretical passband 
A/ of a television channel and its optical 
equivalent J7, ( /> is, therefore: 

#.(/) = (AWr)* = AW)* (64) 

For normal blanking percentages the 
proportionality factor has the value K = 
(7//0.85)*. The product (N c(h )n r ) has 
the dimension (length) ~ 2 , and its recipro- 
cal represents a rectangular area of uni- 
form transmittance which may be re- 
garded as an equivalent point image or sam- 
pling aperture of a theoretical television channel. 
This equivalent sampling aperture is 
often referred to as a "picture-element." 
The term is misleading because the con- 
cept of an element implies an invariable 
intensity distribution in a small area of 
fixed size. A process which is continuous 
in one coordinate forms an infinite num- 
ber of point images and its true "ele- 
mental" area is infinitesimal. Only a 
point raster process can produce an 
elemental area of finite size. 

The concepts of a two-dimensional aper- 
ture df having the exact response characteristic 
of a theoretical television channel is useful for 
an interpretation of electrical random 
fluctuations (noise) in terms of optical 
deviations. 

Electrical signal-to-noise ratios are 
usually computed for a given passband 
A/ having a theoretically sharp cutoff. 
This evaluation is analogous to the proc- 
ess of sampling a two-dimensional grain 
structure with a measuring aperture S m 
= df of known geometry to determine a 
reference value [R] m for the particular 
random structure (see Part II D). The 
sources of electrical random fluctuations 
in a television system (see Fig. 65) can, 
therefore, be replaced by random part- 
icle structures scanned by a hypothetical 
television camera. The scanning aper- 
ture of this camera is infinitesimal and 



Otto H. Schade: Television Grain Structure 



119 









-J 




- 1 


1 






JL . 






-r" 




'5 


M=l , T 






1 '/n 






'n~ 










-110 


_t_t 





-1 

I 


bt 


X"^"/^ 


1 14 
f '' 



VERTICAL SINE-WAVE 
PATTERN N v =2 

n 7 =12 
n s =14 



HORIZONTAL SINE^WAVE 
PATTERN 




*bh Fig. 79. Corresponding lengths and time 

intervals of television frame and signals. 




.= 2 /N C (hH r- 



68 10 12 14 



Fig. 80. Equivalent point image or sam- 
pling aperture of theoretical television 
channel. 

its output signals are modified by the 
equivalent passband JV e ( 8 ) of the system 
elements following the "noise" source. 
The granularity (noise level) of the struc- 
ture is computed by assuming that it is 
scanned with a measuring aperture d m = 



df which must fill the requirements that 
its signals are indistinguishable from 
electrical fluctuations in the correspond- 
ing theoretical channel A/. The hori- 
zontal sine-wave response of <5/ is, there- 
fore, constant in the passband N e (h) = 
A^ C (fc), its equivalent vertical passband is 
N e(v ) = n r , and the aperture signals in 
different raster lines are uncorrelated. 

The frequency spectrum of 5/ in the 
vertical coordinate may be determined as 
follows : it is assumed for simplicity that 
no interlacing is used. A vertical cross 
section in the frame area corresponds to a 
series of amplitude samples taken from 
the electrical aperture signal at the line 
intervals t h (see Fig. 79). The sampling 
of constant electrical sine-wave signals 
by the raster process results in a series of 
constant sample amplitudes (N v = 0) for 



120 



August 1953 Journal of the SMPTE Vol. 61 



all frequencies which are integral mul- 
tiples of the line frequency ft, = l/th- 
When the signal frequency is changed by 
an increment A'/ = /A/2, the sample 
amplitudes alternate between two fixed 
values at a frequency corresponding to 
the line number N v = n r . Frequency 
increments A'/ between A'/ = and 
A'/ = f h /2 as well as between A'/ = / A 
and A'/ = fh/2 cause a sequence of 
sample amplitudes identical with those 
obtained with an aperture sampling opti- 
cal sine-wave patterns with line numbers 
from N v = to N v = n r . The ampli- 
tudes of the electrically taken samples 
vary according to the phase relation 
between sampling points and sine-wave 
signal, just as aperture samples depend 
in magnitude on the relative phase be- 
tween the raster lines and the optical 
sine-wave pattern. The electrical sam- 
ples can, therefore, be attributed to 
a hypothetical aperture 5/ scanning sine- 
wave patterns with a line number range 
AT, = to N, = n r . This range of line 
numbers is sampled repetitively through- 
out the video frequency band in every 
increment A'/ = fh/2. Because the elec- 
trical response within any one of these 
small sections of the video passband is 
substantially constant, the rms values of 
the aperture signals at any one line 
number N v = to n r from all sections 
A'/ are alike. The vertical sine-wave 
response of 5/ is constant between N = 
and N = n r and independent of the hori- 
zontal response characteristic of the 
video system. 

The raster characteristic (Fig. 70) 
transforms this limited constant ampli- 
tude spectrum into an infinite frequency 
spectrum (see section B4) which is subse- 
quently limited by the real aperture 8b 
following the raster process, and results 
in an overall response identical with the 
response characteristic of db- An electrical 
"noise" source followed by a "flat" video 
channel A/ with theoretical rectangular cutoff 
can, therefore, be replaced by a random par- 
ticle structure scanned by an aperture d/ having 
constant sine-wave response in both x- and y- 



coordinates within the range of line numbers 
N e (h) and n r respectively. The equivalent 
passband of this hypothetical scanning 
aperture is N t (f) = (JV(iplf)l as stated 
by Eq. (64). 

It is of interest to determine the geo- 
metric characteristics of this aperture. 
A harmonic synthesis of the horizontal 
aperture cross section from its response 
characteristic (see Eq. 54) shows that the 
transmittance TA varies as a (sin *)/* func- 
tion (Fig. 80) and has positive and nega- 
tive portions decaying slowly to zero at 
infinity. f The central peak between the 
first zero points has a dimension So = 
2/N C (h)> The aperture transmittance T V 
in the vertical coordinate (y) can be 
given a rectangular shape with constant 
transmittance r v = 1 and a width SQ = 
l/n r . This dimension meets the require- 
ments N e (v) = n r and that signals in dif- 
ferent scanning lines be uncorrelated. 
The continuous sine-wave response (in 
y) of this rectangular aperture has a 
(sin x)/x form with a first zero at N v = 
2n r . In conjunction with the raster char- 
acteristic, however, the (sin x)/x response 
produces a frequency spectrum identical 
with that from a constant aperture re- 
sponse in the range N/n r = to 1. 
The (sin x)/x response "folded" into 
this range results in unity rms response 
factors when the response factors of all 
input frequencies giving the same output 
frequency, are combined. 

3. Horizontal Sine-Wave Response and 
Aperture Characteristics of 
Electrooptical Systems 

(a) General Formulation. The principal 
elements determining the horizontal 
response characteristic of a television 
system are indicated in the block dia- 
gram Fig. 65. The horizontal sine- wave 
response of television systems can be 
made very dissimilar to that of optical 
systems by adjustment of the response 

f An optical synthesis of images with aper- 
tures containing negative flux components 
is discussed in the following section. 



Otto H. Schade: Television Grain Structure 



121 




RELATIVE LINE NUMBER (N/N C ), OR RELATIVE FREQUENCY 

Fig. 81. Aperture correction circuit and response characteristics. 



characteristic r? of the video system. The 
response of amplifiers and filter circuits 
is normally constant within a substantial 
portion of their passband but can also 
be given a rising characteristic by correc- 
tive networks. The sine-wave response 
r% c of a two-stage amplifier circuit for cor- 
recting the sine-wave response of camera 
tubes is shown in Fig. 81. A phase- 
correcting circuit is used in conjunction 
with the amplitude-correcting circuits. 
Electrical networks of this type are 
termed aperture-correction circuits because 
they can completely or partially compen- 
sate the decreasing horizontal response 
r$h of two-dimensional apertures. The 
horizontal response of an electrooptical 
system is given in general by 



where 



r ef 



= (renrecref)(f/f c ) = overall electri- 
cal response characteristics 

= retfe-2 = response of preamplifier 
(reiz = 1 for an equalized pre- 
amplifier, see discussion in 3(c) 

= response factor of aperture cor- 
rection circuits (Fig. 81) 

= response factor of low-pass filter 
(Fig. 82) 

= horizontal cutoff resolution (Eq. 
63)) 

= (rf(a)r$(b)\NiN c )h = response 
characteristic of all two-dimen- 
sional system apertures. 



(b) Apertures and Aperture Effects of 
Electrical Elements. An aperture correc- 
tion r^ c = \/r$ results in a system re- 
sponse equal to that of the cutoff filter: 



122 



August 1953 Journal of the SMPTE Vol. 61 



1.0 



I 1 10 10 1 111011101 




0.5 10 

RELATIVE LINE NUMBER (N/N c ) h OR FREQUENCY (-f/f c ) 

Fig. 82. Sine-wave response of electrical low-pass filters. 



EYE, d/V=4 

AVERAGE FIELD LUMINANCE 
:;B=4 TO IOFT.-L 




500 



LINE NUMBER (N) 



1000 



Fig. 83. Sine-wave response of the eye at moderate brightness 
levels and a viewing distance d = 4F. 



^() = nf- The degree of aperture cor- 
rection permissible in a particular case 
depends on the horizontal resolution 
N C (h) of the television system and the 
viewing distance which determines the 
relative aperture response of the eye. 
When the cascaded response character- 
istic rif,( S )r$ eye , including the visual system, 
departs markedly from that of an optical 



aperture (excessive high-frequency re- 
sponse), the corresponding retinal point- 
image has abnormal characteristics be- 
cause it has a transmittance (r) with 
negative portions (compare Fig. 80). 
Such apertures cause edge transitions 
distorted by "transient" overshoots or 
oscillations, and result in a relief effect or 
multiple contour lines. It is not difficult 



Otto H. Schade: Television Grain Structure 



123 



2.0 

1.5 

i 

g '.o 
X 

ft 05 



I 

tn 



-1.0 



I I 
CURVE] NS Sxio- 2 



57 1.96 1.92 0.07 

2 153 0.65 1.27 0.40 

3 340 0.29 0.44 0.68 

77 1.3 -1.44 0,11 
46 2J8 -1.19 0.03 

SEE A 

= 0+2+3+445) 1.0 (DASHED 
LINE) 



-0 





-0.5T 



20O 300 

LINE NUMBER (N) 



500 



Fig. 84. Synthesis of a "flat "-response characteristic with sharp cutoff 
by addition of 3 positive- and 2 negative-response characteristics of round 
apertures with uniform transmittance. 



to see that a system response r^ (8) extend- 
ing beyond two-thirds of the passband 
of the eye (see Fig. 83) can be given a 
constant value with sharp cutoff without 
causing an abnormal overall response in 
the retinal image. When the cutoff of 
the television system, however, occurs in 
the lower half of the visual passband, due 
to low system resolution or close viewing 
distances, aperture correction must be 
limited to a system response r$( S ) having 
more gradual cutoff, to prevent ab- 
normal optical conditions in the retinal 
image, f 

The effects of apertures having negative 
transmittance can be demonstrated by a 

f This subject will be discussed further in 
Part IV. 



photographic correction process. The 
response characteristic (6) of the point 
image shown in Fig. 84, for example, can 
be synthesized by superimposition of 
three positive and two negative com- 
ponents. Images can be synthesized by 
two sets of out-of-focus projections with 
appropriate lens stops. The positive- 
aperture effects are combined in one 
plate by a triple exposure. The negative- 
aperture plate is made by a double ex- 
posure with positive apertures and re- 
versed in polarity in a contact print. A 
composite print from the positive and 
negative plates in register is shown in 
Figs. 85a and b and illustrates the tran- 
sients and sharp cutoff (in both image 
coordinates) produced by the response 



Figures 85a, 85b and 85c are on plate pages 116 and 117. 



124 



August 1953 Journal of the SMPTE Vol. 61 




RELATIVE LINE NUMBER (N/N C )(,OR RELATIVE FREQUENCY 



Fig. 86a. Normalized response characteristics for "flat" 
channel with sharp-cutoff filter (Fig. 82) in cascade with ex- 
ponential apertures and 1 X aperture correction (Fig. 81 ). 




RELATIVE LINE NUMBER ( N / N c)h R RELATIVE FREQUENCY (f/f c ~) 

Fig. 86b. Normalized response characteristics for "flat" 
channel with sharp-cutoff filter (Fig. 82) in cascade with ex- 
ponential apertures and 2X aperture correction (Fig. 81). 



characteristics, Fig. 84. The similarity 
with an over-compensated television 
process can be increased by the addition 
of a raster process as shown in Fig. 85c. 
At increased viewing distances the un- 
desirable transients disappear, because 
the overall response is then given a nor- 
mal shape by the eye characteristic. 

(c) Generalized Response and Aperture 
Characteristics. The sine-wave response 
characteristics of electrooptical systems 
have been computed in normalized units 
as a function of system parameters to 



simplify numerical evaluation. The 
curve families Figs. 86 and 87 are plots 
of Eq. (65) for an electrical response rgwith 
four values of aperture correction and two 
different filter characteristics, in cascade 
with various optical apertures. The 
cascaded response of all two-dimensional 
apertures in the system under considera- 
tion is closely approximated by the re- 
sponse characteristic rrf) of one equiva- 
lent exponential aperture (Fig. 44 and 
Table VII, Part II). The parameter 
(N e (f)/N c ) h specifies the equivalent pass- 



Otto H. Schade: Television Grain Structure 



125 



.5 1.0 0.6 0.71 0.6 0.5 0.4 0.3 BB 



4.07 3.37 2.68 2.22 1.93 1.53 I.I I 0.72 0.41 HH 




RELATIVE LINE NUMBER (N/N c ) h OR RELATIVE FREQUENCY (f/f c ~) 



Fig. 86c. Normalized response characteristics for "flat" 
channel with sharp-cutoff filter (Fig. 82) in cascade with ex- 
ponential apertures and 4X aperture correction (Fig. 81). 



CURVE oo 1.5 1.0 0.8 0.71 0.6 0.5 0.4 0.3 




RELATIVE LINE NUMBER (N/N C )(, OR RELATIVE FREQUENCY 



Fig. 86d. Normalized response characteristics for "flat" 
channel with sharp-cutoff" filter (Fig. 82) in cascade with ex- 
ponential apertures and 6X aperture correction (Fig. 81). 



126 



August 1953 Journal of the SMPTE Vol. 61 




RELATIVE LINE NUMBER (N/N e ) K OR RELATIVE FREQUENCY 



Fig. 87a. Normalized response characteristics for ''flat" 
channel with gradual-cutoff filter (Fig. 82) in cascade with 
exponential apertures and IX aperture correction (Fig. 81). 




RELATIVE LINE NUMBER 



OR RELATIVE FREQUENCY (V*e) 



Fig. 87b. Normalized response characteristics for "flat" 
channel with gradual-cutoff filter (Fig. 82) in cascade with ex- 
ponential apertures and 2X aperture correction (Fig. 81). 



band of this aperture relative to the 
theoretical bandwidth N cW of the elec- 
trical system. The equivalent passband 
N()h of the response characteristics is 
specified likewise in relative units by the 
ratio a = (N e ()/N c )h defined as the 
bandwidth factor in section Dl. 

If the system is considered as a purely 
electrical network, the aperture transmit- 
tance Th of the system is its response to a 



single impulse of infinitesimal duration. 
The optical equivalent is the response of 
the electrooptical system to isolated lines 
of infinitesimal width. The impulse 
shapes or aperture cross sections (trans- 
mittance Th) corresponding to the re- 
sponse characteristics Figs. 86 and 87 
have been computed by a Fourier syn- 
thesis (Eq. (54)) which is valid for the 
condition of zero phase shift or a linear 



Otto H. Schade: Television Grain Structure 



127 




O.5 1.0 

RELATIVE LINE NUMBER ( N / N c)h OR RELATIVE FREQUENCY (f/f c ~) 

Fig. 87c. Normalized response characteristics for "flat" 
channel with gradual-cutoff filter (Fig. 82) in cascade with ex- 
ponential apertures and 4X aperture correction (Fig. 81). 




RELATIVE LINE NUMBER (N/N C )K OR RELATIVE FREQUENCY (f/0 

Fig. 87d. Normalized response characteristics for "flat" 
channel with gradual-cutoff filter (Fig. 82) in cascade with ex- 
ponential apertures and 6X aperture correction (Fig. 81). 



128 



August 1953 Journal of the SMPTE Vol. 61 







-0.5 



1234 

RELATIVE DISTANCE ( X / XQ ) OR RELATIVE TIME(Vf ) 



Fig. 88. Impulse forms or aperture transmittance obtained 
with response characteristics Figs. 86 and 87. 



phase delay within the system passband. 
The aperture cross section (r*) depends, 
again, on the relative equivalent pass- 
band (a) as shown in Fig. 88. 

Phase distortion between sine- wave 



components can occur in electrical and 
also in optical elements (lenses, etc.). 
In terms of aperture properties it is 
caused by an asymmetric aperture trans- 
mittance (coma for example) and results 



Otto H. Schade: Television Grain Structure 



129 







in asymmetric edge transitions. Phase 
distortion is of little importance in the 
transfer of random deviations, but it is 
an important aperture property deter- 
mining waveform distortion. The meas- 
urement and effects of phase distortion 



will be discussed with the subjects of im- 
age sharpness and definition in Part IV 
of this paper. 

The electrical response to a step function, or 
the corresponding electrooptical response to a 
sharp edge, is obtained by integration of 



130 



August 1953 Journal of the SMPTE Vol. 61 




Otto H. Schade: Television Grain Structure 



131 



CURVE -oo 1.5 1.0 0.8 0.71 0.6 0.5 0.4 0.3 




0.5 1.0 

RELATIVE LINE NUMBER ( N / N c)h OR RELATIVE FREQUENCY (f/f c ~) 

Fig. 91a. Normalized response characteristic for "peaked" 
channel with sharp-cutoff filter (Fig. 82) in cascade with ex- 
ponential apertures and IX aperture correction (Fig. 81). 



CURVE oo 1.5 |.o 0.8 0.71 0.6 0.5 0.4 0.3 




132 



RELATIVE LINE NUMBER (N/N C )|, OR RELATIVE FREQUENCY 0/*c) 



Fig. 91b. Normalized response characteristic for "peaked" 
channel with sharp-cutoff filter (Fig. 82) in cascade with ex- 
ponential apertures and 4X aperture correction (Fig. 81). 

August 1953 Journal of the SMPTE Vol. 61 



RELATIVE LINE NUMBER (N/N C )(,OR RELATIVE FREQUENCY (/*c 




Fig. 91c. Normalized response characteristic for "peaked" 
channel with sharp-cutoff filter (Fig. 82) in cascade with ex- 
ponential apertures and 6X aperture correction (Fig. 81). 



the impulse function and shown in Fig. 
89a for zero phase distortion. The nor- 
malizing or "filtering" effect of larger two- 
dimensional apertures (low a) in cascade 
with the "abnormal" electrical response 
characteristics is evident. The peak-to- 
peak transient ripple can be estimated 
from the a-value by the curve shown in 
Fig. 89b. 

The response characteristics Figs. 86 
and 87 include a complete video system 
and are required for calculation of 
signal-to-deviation ratios originating in 
electrical sources ahead of the video 
amplifier or hi photographic grain pat- 
terns ahead of the television system. 
Fluctuations (? ) (see Fig. 65) in the 
photo-emission current of the camera 
rubes are usually of negligible magnitude 
compared to fluctuations (?i) originating 
in the camera tube beam-current or in 
the current of the first amplifier stage. 



(Fluctuations (e t ) introduced later in the 
process of signal transmission (radio 
links, etc.) vary in magnitude according 
to distance and will be assumed negli- 
gible in this analysis.) The location of 
the dominating source ?i in the system 
is shown in more detail in Fig. 90a. The 
diagram Fig. 90b indicates the response 
characteristic r^\ of the capacitive input 
circuits in which the response decreases 
with frequency, and following the re- 
sponse characteristic r? 2 (high-peaking 
circuit) by which the signal response is 
again corrected to a constant-amplitude 
response rjirj 2 = r^\z = 1. The equiva- 
lent diagram Fig. 90b illustrates that 
fluctuations e\ originating in a camera 
tube have a constant-amplitude fre- 
quency spectrum and are termed flat 
channel noise. Fluctuations e a from the 
first video amplifier are modified hi the 
input-correction circuit to have a sine- 



Otto H. Schade: Television Grain Structure 



133 



RELATIVE LINE NUMBER ( N / N c)h OR RELATIVE FREQUENCY (f/*c) 




Fig. 92a. Normalized response characteristic for "peaked" 
channel with gradual-cutoff filter (Fig. 82) in cascade with ex- 
ponential apertures and 1 X aperture correction (Fig. 81 ). 




^5 1.0 

RELATIVE LINE NUMBER (N/N c ) h OR RELATIVE FREQUENCY (f/* c ~) 

Fig. 92b. Normalized response characteristic for "peaked" 
channel with gradual-cutoff filter (Fig. 82) in cascade with ex- 
ponential apertures and 2X aperture correction (Fig. 81). 

wave spectrum with amplitudes propor- ^/3 at N = N c(h) to obtain N el = N cW 

tional to frequency. This type of fluctua- for the theoretical condition (see section 

tion is termed peaked-channel noise. The D2.) In cascade with aperture correction 

response factor of the theoretical tri- circuits (r^ c ), the cutoff filter (r?/), and 

angular characteristic with sharp cutoff the apertures (r^(&)) following the elec- 

has been normalized to the value r%\ = trical system, the frequency spectrum 



134 



August 1953 Journal of the SMPTE Vol. 61 




RELATIVE LINE NUMBER (N/N c ) h OR RELATIVE FREQUENCY 



Fig. 92c. Normalized response characteristic for "peaked" 
channel with gradual-cutoff filter (Fig. 82) in cascade with ex- 
ponential apertures and 4X aperture correction (Fig. 81). 



for peaked channel noise is modified 
to the forms shown by the normalized 
response characteristics Figs. 91 and 92. 
In the Fourier synthesis of the corre- 
sponding aperture transmittance (or 
impulse shape), the cosine terms are 
changed to negative sine terms because 
of a 90 phase shift in the reactive circuit 
(except for the lowest-frequency terms 
which can be neglected because of their 
small amplitude). The impulse wave- 
form or horizontal-aperture transmit- 
tance of these characteristics is, therefore, 
a differentiated pulse as shown in Fig. 
93 (obtained by differentiating the cor- 
responding flat-channel pulse shapes 
(Fig. 88)). 

4. Aperture Response of Camera 
Tubes and Kinescopes 

The sine-wave response of television 
camera tubes is measured with the help of 
vertical and horizontal cross-section 



selector circuits 3 using sine-wave test pat- 
terns or a conversion from square-wave 
response characteristics. The sine-wave 
response is determined primarily by the 
aperture characteristic of an electron 
beam but is modified by a number of 
secondary aperture effects, such as 
image-plate granularity, out-of-focus con- 
ditions (particularly in iconoscope and 
image-iconoscope types which have in- 
clined targets), or the aperture of elec- 
tron-image sections. 

The sine-wave response of camera 
tubes, decreases, therefore, more rapidly 
than that of a kinescope and the effective 
aperture is a composite of several expo- 
nential ( e ~ (r/r f )2 ) spot sizes. The sine- 
wave response of a typical camera tube 
is shown in Fig. 94. Although measured 
recently on image orthicons having 3-in. 
faceplates this characteristic may be re- 
garded as typical of good commercial 
camera tubes in use at this time, includ- 



Otto H. Schade: Television Grain Structure 



135 




I 2 3 

RELATIVE DISTANCE (X/X ) OR TIME (t/t<>) 
UNIT:X =l/N c ,t = '/ 2f C 



Fig. 93. Impulse forms or aperture transmittance obtained 
with response characteristics Figs. 91 and 92. 



136 



August 1953 Journal of the SMPTE Vol. 61 



Table XVI. Equivalent Passband .V, and Approximate Limiting Resolution N c 

of Television Components. 

#. N e * r$ 



Square spot = 1 


0.49 N e 


Part II, Fig. 41 


Round spot = 1 


0.45 N e 


" 42 


Round spot = cos 2 r 


0.38 N e 


43 


Exponential spot = t ~( r / r J 


0.23 AT, 


46a 


Exponential spot = e ~( r / ro > 2 


. 32 N e 


" " " 44 




0.20 JV, 


(av. field luminosity ft 


Eye at viewing ratio: d/V = 2 


376 1880 


4 to 10 ft-L) 


4 


188 940 


Fig. 81 


8 


94 470 





Camera tubes 



Image iconoscope 


200 


800 (approx.) 




Image orthicon (type 5826) 


200 


800 


Fig. 94 


Image orthicon 4|-in. faceplate 


250 


1300 


" 95 


Vidicon (type 6198) 


158 


650 


" 96 


Kinescopes 


265 


920 


" 97 




420 


1500 






500 


1800 






800 


3000 





.V r * at response rf ^ 0.02. 



ing iconoscopes and European orthicon 
and image-iconoscope types, f Accord- 
ing to the author's experience and meas- 
urements, there is no evidence supporting 
statements often found in the literature 
that high-velocity tubes, such as the 
iconoscope types, have higher resolution, 
i.e., a better response characteristic than 
low-velocity tubes. Theoretical advan- 
tages in one type are balanced by dis- 
advantages imposed by tube geometry 
or auxiliary components in other types. 
The relative performance of different 
tubes is often thoughtlessly compared, 
disregarding large differences in the size 
of the storage surface and its capacitance. 
The response characteristics of an experi- 



t A recent publication 4 claims a resolution 
limit of 900 to 1000 lines for the center of a 
modern image iconoscope and about 700 
lines at the edges. Low-velocity types have 
very little astigmatism and a substantially 
uniform spot diameter for correctly ad- 
justed operating conditions. 



mental high-definition image orthicon 
having a larger storage surface is shown 
in Fig. 95, and that of a small vidicon in 
Fig. 96 (both are low-velocity types). 

The equivalent passband N e of the 
characteristic in Fig. 94 is 200 ; this value 
may be regarded as representative of 
good commercial camera tube perform- 
ance at the present time. Appropriate 
values for resolution (N e ) and equivalent 
passband N e of camera tubes are listed 
in Table XVI. 

The sine-wave response characteristic of a 
kinescope is shown in Fig. 97. The meas- 
ured electrooptical response departs more 
or less from that of theoretical electron 
beams because of aberrations and the 
additional aperture effect of the particle 
structure of the screen phosphor. Uni- 
formity of the response in the frame area 
and resolution depend on the design of 
the electron gun, electron lens, and the 
operating conditions. The resolution of 
kinescope types may vary from a few 
hundred to several thousand lines. The 



Otto H. Schade: Television Grain Structure 



137 



response characteristic retains a shape 
similar to that in Fig. 97. Approximate 
values of the equivalent passband (N e ) 
and limiting resolution (AQ for a variety 
of kinescopes are listed in Table XVI. 



Fig. 94. Sine-wave response (r 
of commercial camera tubes. 



Fig. 95. Sine-wave response (r$) of experi- 
mental high-definition camera tubes. 



STORAGE-TYPE CAMERA TUBE 
EQUIVALENT PASSBAND N e = 2OO 




200 400 600 

LINE NUMBER (N) 




IMAGE ORTHICON, 4 '/g FACE PL ATE 
TARGET SPACING: 0.5 TO 1.5 MILS 
TARGET BIAS: I.5TO 2.5 VOLTS 
EQUIVALENT PASSBAND : N e =250 



500 



LINE NUMBER (N) 



1000 




Fig. 96. Sine-wave response 
(r$) of small camera tube (vidi- 
con) with photoconductive tar- 
get. 



138 



August 1953 Journal of the SMPTE Vol. 61 



KINESCOPE 

EQUIVALENT PASSBAND : N c = 265 




500 



1000 



LINE NUMBER (N) 
Fig. 97. Sine-wave response (r$) of a kinescope. 



D. EQUIVALENT PASSBANDS AND SIGNAL-TO-DEVIATION RATIOS 



1. General Formulation 

The passband of an electrooptical sys- 
tem, such as a television system, has a 
definite value defined by the electrical 
cutoff frequency / c , or more adequately 
by the passband N e (f) = C/V C ( *>,.)* of the 
theoretical measuring aperture. Because 
of the relation f/f e = N (h )/N c(h) , fre- 
quencies and line numbers in the hori- 
zontal coordinate have been expressed 
in relative units (N/N c )h permitting 
representation of the system response by 
generalized characteristics. The equiva- 
lent horizontal passband N e ( 8 )h of an electro- 
optical system can hence be stated in the 
general form 



aN c 



(A) 



(66) 



where 



*(f/fc) 



''(N/Nc)h 



(rert)\N/Nc)h d(N/N c ) h = rela- 
tive equivalent passband 

= response characteristic of 
electrical system following 
source of deviations 

= response characteristic of 
aperture system following 
source of deviations. 



The system response in the vertical co- 
ordinate is determined completely by the 
raster constant n r and the two-dimen- 
sional apertures of the system, and has 
likewise been expressed in relative units 
N v /n r . The equivalent vertical passband 
Ne() V of the system, can hence be stated 
in the general form. 

#.(.). = |9r (67) 

The relative equivalent passband /3 = 
N.M./n r is given by Eqs. (59), (60), or 
Fig. 76. For deviations of electrical 
origin, the analyzing aperture d a is the 
measuring aperture 5/ of the theoretical 
television system. (See section G2.) 
The equivalent vertical passband of 
5 a = 8 f is hence JV<) n r and the 
vertical passband of the system is given 
exactly by Eq. (60), i.e., N e(t ) V = N e(b ) 
and /3 = N e (b)/n r . 

The factors a and /3 are defined by 
Eqs. (66) and (67) as ratios of the equiva- 
lent horizontal or vertical passband of 
the system to the corresponding theoret- 
ical passband of the television channel 
and are, therefore, termed bandwidth 
factors. 



Otto H. Schade: Television Grain Structure 



139 



_The equivalent symmetric passband 
Ne( 8 ) of the system is the geometric mean 
of its equivalent horizontal and vertical 
passbands : 

JV e(8) = (a/8)*(AT c(A) P )J (68) 

The corresponding bandwidth factor 
(a/3)* of the system is the geometric 
mean of the horizontal and vertical band- 
width factors. 

By combining Eq. (68) with Eq. (53), 
the signal-to-deviation ratio [R] s at any 
point in an electrooptical system can be 
stated in the convenient form: 

[R], = [R} m (J?e(m)/JVe(f))/(aW7* (69) 

The meaning of the symbols is summa- 
rized for easy reference : 

\R] m = Signal-to-deviation or signal-to- 
noise ratio at origin of devia- 
tions 

Ne(m) = Equivalent passband of aper- 
ture with which [R] m is com- 
puted or measured 

JV,(/) = (N e (h)n r )* = theoretical aper- 
ture of television channel 

a = Horizontal bandwidth factor 
(Eq. (66)) 

/3 = Vertical bandwidth factor (Eq. 
(67)) 

7s = product of all point gammas be- 
tween origin of deviation and 
point of observation. 

Deviations may originate at a number 
of points in the electrooptical system 
indicated in Fig. 65. The deviations 
from the various sources are computed 
separately (compare Part II) and com- 
bined by forming their rms sum. 
Deviations ($) originating in the grain struc- 
ture of a preceding motion-picture process are 
transferred through the entire television 
system and observed in the final image. 
Fluctuations originating in the electrical sys- 
tem are displayed likewise as two- 
dimensional deviations in a picture 
frame, but they are also observed and 
measured as signal-to-noise ratios at various 
points of the electrical system. In all 
cases the signal-to-deviation ratio [R] s or 
signal-to-noise nilio [R] may be com- 



puted with Eq. (69) by determining the 
proper reference values, bandwidth fac- 
tors, and point gammas of the system 
elements involved in the transfer of sig- 
nals and deviations. 

2. The Reference Values [R] m and N e(m) 

The signal-to-deviation ratio at the 
source is either computed or determined 
by measurements with an aperture of 
known equivalent passband N e (m). Opti- 
cal deviations $ originate in a photographic- 
system preceding the television process 
and appear in the projected film image 
(AQ in Fig. 65) which can be regarded as 
the source of deviations. In a motion- 
picture transmission by a television sys- 
tem, the normal motion-picture projec- 
tion lens <5 3 is replaced by the lens 6 of 
the television film camera (Fig. 65). 
When the lenses are of equal quality (5 
= 63), the_ measuring aperture is simply 
ffe(m) = JV( P ), and the reference signal- 
to-deviation ratio is [R] m = [R] p , where 
JV e (p) and [R] p are the equivalent pass- 
band and signal-to-deviation ratio of the 
normal motion-picture process as com- 
puted in Part IL When the lenses are 
not identical, N e (m) can be computed 
with l/A- e(w) 2 = 
(l/A-e(o) 2 ) and 



(R] m 



Q (70) 



Electrical fluctuations ? in photoelectric 
currents are normally computed from the 
number of electrons emitted in a time 
unit. The signal-to-noise ratio [R] = 
[R] m can be obtained by the equivalent 
two-dimensional formulation given by 
Eq. (52) where no is the number of elec- 
trons, i.e., the total charge Q f /(H/V) 
in the unit area divided by the charge 
(<7 e ) of one electron : 



(71) 



with the frame charge Q/ = loTfb amp 
sec the electron charge q e = 1.6 X 10~ 19 
amp sec and the measuring aperture 
Ne(m) = Ne(n of the theoretical television 
channel : 



140 



August 1953 Journal of the SMPTE Vol. 61 



[R] 



where 

/o = photo current (amp) 
7/ = frame time ($-$ sec) 
/> = (1 - MO ~ M = blanking 

factor (b = 0.785) 
II IV = aspect ratio (H/V = 4/3) 
#.(/) = (AWr)* (see Eq. (64)). 

Fluctuations ti in the beam current of tele- 
vision camera tubes can be computed simi- 
larly from the values of beam current 
and storage capacitance of the tube. 3 A 
reference signal-to-noise ratio [/?] is 
usually given by the manufacturer for a 
specified frequency channel A/ 8 . The 
reference values for a frequency channel 
A/ are therefore : 



[R] m = 



(73) 



and 



.o.0 = JV 



.cn 



Camera tubes not having an electron 
multiplier, such as iconoscopes, image 
iconoscopes, orthicons (C.P.S. Emitron) 
and vidicons, require the use of high- 
gain camera amplifiers. The current 
fluctuations ? 2 in the first amplifier tube be- 
come the dominant noise source. All 
high-gain camera amplifiers have a 
capacitive input circuit (Fig. 90a) which 
causes the signal-input voltage on the 
first amplifier tube to decrease with fre- 
quency as indicated in the voltage dia- 
gram Fig. 90b. The decreasing sine- 
wave response r^\ is, therefore, compen- 
sated by a corrective network (r? 2 ) to a 
constant signal response r?ir?2 = 1 . The 
noise voltage e a generated by the first 
amplifier current ? 2 is inserted between 
the input and correction circuits, and its 
normal "flat" spectrum is modified by 
the response r^ to a spectrum with rising 
amplitude response termed a "peaked" 
channel. The amplifier circuit can, 
therefore, be represented as a flat (com- 
pensated) signal channel (r?i 2 =1) into 
which a noise voltage e a is introduced 
over a peaked channel as indicated by 



the equivalent voltage diagram Fig. 90c. 
The rms-value []<, of the flat-channel 
noise voltage e can be computed in first 
approximation from the "equivalent 
noise resistance" R^ of the amplifier 
tube 5 and has the value 

[] - 1.3 X 10-'o(/?,,A/)i (74) 

The corrective network r? 2 changes this 
value by the factor 

a, = [},/[}. = 

fXV*o)V//y(///,)]i (75) 

which is the rms value of the gain ratio 
(g/go) in the network. In terms of cir- 
cuit constants the gain ratio is equal to 
the impedance ratio co L/r, which in turn 
must equal the time constant w CR of the 
input circuit to obtain a complete com- 
pensation r?ir? 2 = 1. Integration x fur- 
nishes the value 



= 2irAfCR/\/3 (76) 



where 

C = effective capacitance of input cir- 

cuit in farads 
R = shunt resistance of input circuit in 

ohms. 

For a general formulation it is expedi- 
ent to replace the actual noise source e a 
and the correcting circuit by a noise 
source 2 generating the rms voltage [] 2 
in a flat channel A/ and to change the 
spectrum to a "peaked" frequency spec- 
trum by a correction network having a 
normalized response characteristic and 
the response factor r? 2 = \/3 at / = f e . 
The normalized characteristic r? 2 (see broken - 
line curve in Fig. 9 la) does not change 
the rms value [Zs] 2 , because for r? 2 = 
\/3 at f e , the rms voltage ratio of the 
normalized correction network has the 
value 



(77) 

The signal-to-noise ratio [/?] 2 for am- 
plifier noise (equivalent circuit Fig. 90c) 
is computed as follows : 

The signal is the voltage 7 R developed 



Otto H. Schadc: Television Grain Structure 



141 




by the camera-tube signal current 7 in 
the input resistance R (Fig. 90a), because 
the effect of the shunt capacitance C has 
been compensated by a corrective net- 
work. The noise source is considered as 
a flat-channel noise source having an 
rms voltage [S] 2 = a z [E] a . Because of 
Eq. (77) the noise voltage after the peak- 
ing circuit has the same rms value. The 
measuring aperture for the normalized 
circuit has_ the equivalent passband 
Ne(m) = N e (f) and the signal-to-noise 
ratio is [R] 2 = IR/a 2 [E] a . With the 
values of Eqs. (74) and (76) : 

[*] 2 = 2.137 X lOVCWKA/)* (78) 



The signal-to-noise ratio [R] 2 of prac- 
tical amplifier circuits may have a lower 
value than the one computed with Eq. 
(78) which neglects noise contributed by 
circuit resistances, subsequent amplifier 
stages, and the effects of feedback. These 
contributions are usually small for cir- 
cuits using a pentode input stage (type 
6AC7). They are appreciable for a 
normal triode input- stage but may be 
minimized by the use of special circuits 
and tubes having low grid-plate capaci- 
tance. A typical input stage used in 
older camera amplifiers uses a type 6AC7 
amplifier tube as a pentode with the fol- 
lowing constants: 

R eq = 720 ohm, C = 30 X 10~ 12 farad, 
R = 105 ohm 

The maximum signal current 7( max ) from 
camera tubes not having an electron 
multiplier is of the same order : 7(m ax ) 
0.1 X 10~ 6 amp. With these values Eq. 
(78) furnishes the value [R] Zm ** = 30 in a 
frequency channel A/ = 4.25 X 10 6 
cycles/sec. 

Modern high-gain camera amplifiers 
use special high-transconductance triodes 
with a somewhat higher effective capaci- 
tance but a much lower equivalent noise 
resistance R eq ^ 110 ohm in a "cascode" 
circuit, resulting in an improved signal- 
to-noise ratio [R] 2 m a* ^ 70 for A/ = 4.25 
X 10 6 cycles/sec. The variation of 
[R]z as a function of signal current, fre- 



142 



August 1953 Journal of the SMPTE Vol. 61 



quency channel or other parameters is 
readily computed with Eq. (78). Refer- 
ence values for various camera-tube 
types are listed in Table XVII. 

3. Bandwidth Factors 

The ratios of the equivalent passbands 
of an electrooptical system to the theoreti- 
cal equivalents A r C (/o and n r of its electri- 
cal system (Eqs. (66), (67), (68)) have 
been termed bandwidth factors. A sys- 
tem containing two-dimensional aper- 
tures has horizontal and vertical band- 
width factors a and ft and its equivalent 
symmetric aperture has a bandwidth fac- 
tor (a/3)* which is their geometric mean. 
The horizontal bandwidth factor a includes 
the response r$ of two-dimensional aper- 
tures as stated by Eq. (66). It is used to 
compute the signal-to-deviation ratio 
in the final image frame for deviations 
originating (1) in a photographic proc- 
ess ahead of the television system or (2) 
in electrical noise sources. In case 1 the 
two-dimensional aperture response is 
rj, = (r^ (a) r^(6)). In case 2, r$ = rt (b) , 
because only apertures following the 
electrical network are in the system 



may include the response of the 
eye). Integration of the squared nor- 
malized response characteristics Figs. 86 
and 87 furnishes electrooptical band- 
width factors a for case 1 and for case 2 
with electrical flat channel noise sources 
e\. For convenience in plotting, the cor- 
responding square roots a* are shown in 
Fig. 99. The bandwidth factors for 
peaked channel noise sources ? have 
been computed similarly for the charac- 
teristics Figs. 91 and 92, and their square 
roots are shown in Fig. 100. 

For deviations ^ of optical origin, 
the vertical bandwidth factor may be 
obtained from Fig. 76 or computed with 
Eqs. (59) or (60). For deviations of elec- 
trical origin (e\ or e->) the exact value of 
the vertical bandwidth factor of the sys- 
tem is given by 

/3 ( \f I \ ( K 1 \ 

It has been shown that the electrical 
circuit response of a television system has 
no effect on the vertical aperture re- 
sponse of the system. The vertical band- 
width factor of electrical elements is. 
therefore, 0=1. The bandwidth far- 



Table XVII. Maximum Signal-to-Noise Ratios [R] m (max) of Various 
Camera-Tube Types for Theoretical Channel A/ = 4.25 Me. 







Approx. 
target 
capaci- 












tance 






Noise** 


Tube type 


Use 


(MM/) 


A/w) 


[R] m ma, 


: source Spectrum 


Iconoscope 


Film Pickup 


10000 


0.1 


70 


? 2 peaked 


Vidicon type 6198 


Film " 


2200 


0.45 


315 


ez peaked 


Image iconoscope 


Live " 


6000 


0.1 


70 


? 2 peaked 


Orthicon* (without 


Live " 


700 


0.1 


70 


ez peaked 


multiplier) 












Image orthicon 












Type 5820 


Live " 


100 


10 


34 


4 flat 


5826 


Live " 


375 


10 


66 


?i flat 


High-definition (4^- 












in. faceplate) image 












orthicon 


Live " 


1100 


20-40 


120 


ei flat 



* Similar to G.P.S. Emitron. 

** See Fig. 98. 

Note: [R] m max for e-i is obtained only with modern cascode input circuits (see text). 



Otto H. Schade: Television Grain Structure 



143 




0.5 1.0 

RELATIVE PASSBAND OF APERTURE 



1.5 



Fig. 99a. Bandwidth factors for "flat" channel noise sources 
with sharp-cutoff filter (Fig. 82) and aperture correction (Fig. 
81 ) in cascade with exponential aperture. 



tor (#)* of the equivalent aperture of 
electrical networks in an electrooptical 
system (excluding optical elements) has, 
therefore, a value m? = a?, i.e., it is 
equal to the square root of its horizontal 
bandwidth factor m. The new symbol m 



is introduced to avoid confusion and indi- 
cate that this factor is reserved for purely 
electrical systems. According to Eq. 
(66), electrical bandwidth factors m are de- 
fined by 
m = (A/ e /A/) = yV W 2 (///y(///e) (79) 



144 



August 1953 Journal of the SMPTE Vol. 61 



2.5 




0.5 1.0 

RELATIVE PASSBAND OF APERTURE 



Fig. 99b. Bandwidth factors for "flat" channel noise sources 
with gradual-cutoff filter (Fig. 82) and aperture-correction cir- 
cuits (Fig. 81 ) in cascade with exponential apertures. 



where 



A/ e = noise-equivalent passband of the 
electrical system 

A/ = theoretical (rectangular) passband 
of electrical system 

r-% = sine-wave response factor of elec- 
trical system. 



4. Signal-to-Noise Ratios in 
the Electrical System 

The signal-to-noise ratio [R] at dif- 
ferent points in the electrical system 
(compare Eq. 69) reduces to 

[R] = [/ZJ/m7, (80) 



Otto H. Schade: Television Grain Structure 



145 




0.5 1.0 1.5 

RELATIVE PASSBAND OF APERTURE (N e (^)/N C )h 

Fig. lOOa. Bandwidth factors for "peaked" channel noise sources 
with sharp-cutoff filter (Fig. 82) and aperture correction (Fig. 81) 
in cascade with exponential apertures. 



where 



[R] m = signal-to-noise ratio computed 
for the theoretical passband A/ 
at the point of noise insertion 
(see preceding section) 

TO = electrical bandwidth factor com- 



puted for the frequency response 
re between the noise source and 
the point of observation (Eq. 
(79)) 

= point gamma of video amplifier 
between noise source and point 
of observation. 



146 



August 1953 Journal of the SMPTE Vol. 61 




0.5 1.0 

RELATIVE PASSBAND OF APERTURE 



Fig. lOOb. Bandwidth factors for "peaked" channel noise sources 
with gradual-cutoff filter (Fig. 82) and aperture correction (Fig. 81) 
in cascade with exponential apertures. 



Actual measurements of the electrical electrical system and the succeeding 



signal-to-noise ratio are necessarily made 
at points following a cutoff filter, indi- 
cated in Fig. 98 by the index number 3. 
Figure 98 indicates all important electri- 
cal sources, the characteristics of the 



aperture system 5t. The square roots 
m* of the bandwidth factors for circuit 
elements between the noise sources e\ 
(camera tube noise) or 2 (amplifier 
noise) have been computed for two filter 



Otto H. Schade: Television Grain Structure 



147 



Table XVIII. Square Roots of Electrical Bandwidth Factors m*. 





Aperture 


Noise source e\ 


Noise source ez 


Cutoff filter 


correction 


(flat spectrum) 


(peaked spectrum) 


(Fig. 82) 


attf c (Fig. 81) 


mn* 


m 23 * 


Sharp 


1 X 


0.98 


0.914 


cc 


2 X 


1.26 


1.47 


" 


3 X 


1.63 


2.0 


" 


4 X 


2.02 


2.52 


" 


5 X 


2.4 


3.04 


" 


6 X 


2.76 


3.57 


Gradual 


1 X 


0.90 


0.76 


cc 


2 X 


1.09 


1.10 


" 


3 X 


1.36 


1.50 





4 X 


1.68 


1.91 


" 


5 X 


1.99 


2.31 


cc 


6 X 


2.24 


2.70 


characteristics (r^/) 


and four values of 


tion because the 


bandwidth factors m, or, 


aperture correction 


(r? c ), and are listed 


and /3 or their 


square roots have been 



in Table XVIII. 

The calculation of signal-to-noise 
ratios [R] in the electrical system and 
signal-to-deviation ratios [R] s in the 
final image by means of Eqs. (80) and 
(69) respectively, is now a simple opera- 



tabulated or plotted. The values [R] s 
change with signal level and point 
gamma (7) as in photographic systems. 
A comparison requires, therefore, evalua- 
tion of the signal-to-deviation characteristic 
[R] s as a function of screen luminance. 



E. THE SIGNAL-TO-DEVIATION CHARACTERISTIC [R] B = f(B) 
OF TELEVISION PICTURE FRAMES 



Television-signal generators and cam- 
era tubes may be divided into two groups. 
One group, including light-spot scanners 
(flying-spot scanner) and image-dissector 
tubes, has no charge-storing elements and 
operates without auxiliary currents. 
The photoelectric signals are amplified 
by built-in electron multipliers and have 
a sufficiently large magnitude to make 
the noise contribution by amplifier tubes 
negligible. The signal-to-noise ratio 
[R] m is therefore a function of the photo- 
current only (Eq. 72) and varies as the 
half power of the signal current : 



[R] m = [R] = [/?]0 



(82) 



The second group of camera tubes has 
charge-storing elements (mosaics or 
targets), and employs electron beams for 
signal development. This group includes 
camera tubes having photo-emissive 



surfaces such as are used in the icono- 
scope, image iconoscope, orthicon and 
image orthicon, or photoconductive lay- 
ers as used in the vidicon. The image 
orthicon is the only type in use having a 
built-in electron multiplier. It can, 
therefore, develop large signals and has 
a "flat" noise spectrum like that of multi- 
plier phototubes. The signal-to-noise 
ratio [R] m = [R]i, however, varies in 
direct proportion to the signal current, 
because the dominant noise source is the 
constant-beam current 



[R], 



(83a) 



The camera tubes not having electron 
multipliers (iconoscope and orthicon and 
vidicon types) have a relatively small 
signal-current output. Their signal-to- 
noise ratio [R] m = [R]-z is controlled by 
the constant amplifier noise (Eq. (78)) 



148 



August 1953 Journal of the SMPTE Vol. 61 



which has a "peaked" frequency spec- 
trum and [R]z varies in proportion to the 
signal current: 

[R] m = [/?] 2 = [/?] 2max (///) (83b) 



The optical signal-to-deviation ratio [R], 
in one picture frame is computed with Eq. 
(69). With the substitutions from Eqs. 
(82) or (83) for [/?] m , and with ^. (m , = 
N e (f), the optical signal-to-deviation 
ratio for the first group of signal sources 
may be written: 

[*]. = Wo max (7//)l/(0)Tfm (84) 
and for the second group of storage tubes : 

6 (85a) 



and 



,T6 (85b) 



where 

7 r = point gamma of video amplifier 
system 

76 = point gamma of succeeding 
aperture processes including kin- 
escope (72) 

[R] and [R]i = signal-to-noise ratios 
with "flat" noise spectrum 

[R] 2 = signal-to-noise ratio with 
"peaked" noise spectrum 

1. Effect of Transfer Characteristics 
and Point Gamma on [R] ., 

The relation of luminance (B) in a pic- 
ture frame to the signal current / and 
scene luminance or camera-tube expo- 
sure (Ei) is determined by the transfer 
characteristics of the system elements. 
A valid comparison of the signal-to-devi- 
ation ratios obtained with different 
television-camera types requires that the 
overall transfer characteristic (tone scale) 
of the system be identical. This require- 
ment is met when the point gammas 
77* = 7i7t>76 of the television systems are 
alike at the same luminance values. It 
is of interest to examine first the general 
effect of the camera-tube gamma (71) on 
the shape of the signal-to-deviation char- 
acteristic [/?]= f(B), which determines 
the relative visibility of deviations in the 
luminance range. 



The [R] .-characteristic can have dil 
ferent shapes depending on the camera- 
tube gamma (71), even though the over- 
all gamma of the television system has 
fixed values 77-. 

(a) The Relative Signal-to- Deviation 
Ratios [R],/[R]m*x of Constant Gamma Sys- 
tems With Camera Tubes Having Constant 
Gamma. It is assumed that the system 
gamma yr as well as the camera-tube 
gamma 71 have constant values. The 
relative-signal current of the camera tube 
is then simply /// = (Ei/Ai)* 1 , where 
(Ei/i) is the relative exposure. With 
this relation and the substitutions 7,76 = 
7r/7i Eq. (85a) takes the form: 

[R]. = [*]lma*(l/A 



In terms of screen luminance (B/B} = 
(Ei/Ei) yT , this expression may be written 



(86) 

Inspection of Eq. (86) shows that the 
slope of the [/? ^-characteristic is con- 
trolled by the exponent (71/77-) of the 
relative screen luminance (B/f). A 
plot of Eq. (86) furnishes straight-line 
characteristics in log coordinates with a 
maximum value [/?],/[/?]i ma x = 
(7i/7r)/M)* at (B/B) = 1 and the 
constant slope (71/71-) as shown in Fig. 
101 for (a/3) = 1 and an overall constant 
gamma 77- = 1.2. It is seen from Fig. 
101 that only a minor improvement of 
[R] a is obtained in the shadow tones 
B/B = 0.01 to 0.04 by decreasing 71 
below the value 71 = 0.6 at the expense 
of a larger reduction of [R], in the high- 
light values B/& = 0.2 to 1. The pre- 
ferred camera-tube gamma for a con- 
stant-system gamma 77- = 1.2 is there- 
fore 71 optimum 0.6. 

(b) The relative signal-to-deviation 
ratios [R] s /[R] m ** of systems with variable 
gamma. It is impractical and actually 
undesirable to provide a constant overall 
gamma for the television system because 
of the finite limits imposed on the tone 
range by all practical imaging devices. 
According to photographic experience 



Otto H. Schade: Television Grain Structure 



149 



Table XIX. Relative Signal-to-Deviation Ratios [R] s /[R]i max for Image Orthicon 

(Also Iconoscope Film Pickup)* With Linear Amplifier (y v = 1), Kinescope Bias 

E /E = 0.13 (Fig. 21, Part I) and aft = 1. 

/// B/B 



7 1>72 l^Jg/l^Jlmax 71 7r 



0.01 


0.026 


0.015 


0.17 


0.153 


1.15 


0.20 


0.02 


0.057 


0.0185 


0.40 


0.142 


1.15 


0.46 


0.04 


0.125 


0.031 


0.95 


0.132 


1.10 


1.045 


0.07 


0.22 


0.06 


1.45 


0.152 


0.85 


1.23 


0.10 


0.295 


0.095 


1.70 


0.174 


0.75 


1.275 


0.20 


0.47 


0.22 


1.90 


0.247 


0.58 


1.10 


0.40 


0.69 


0.46 


2.00 


0.345 


0.49 


0.98 


0.70 


0.88 


0.77 


2.05 


0.429 


0.39 


0.80 


1.00 


1.00 


1.00 


2.10 


0.476 


0.31 


0.65 


(1) 


(1X2) 


(2) 


(3) 


(4) 


(5) 





Notes: (1) From Fig. 6, Part I. (2) From Fig. 21, Part I, (/// = E/E). (3) Tt 

(4) Eq. (83a). (5) From Fig. 7, Part I. 

* Transfer characteristic for EI IS, Fig. 11, Part I. 

Table XX. Relative Signal-to-Deviation Ratios [R] 8 /[R] 2 max for 
Image Iconoscope, and Orthicon (y t = 1). 



Image iconoscope* 


Orthicon, 


linear vidicon, 71 = 1 


E 1 /E 1 


I/I 


7i 


7,72 


[*]./[*] 


z/t 


7*72 


L^H8/L-'M2 max 


0.01 


0.0035 


3.3 


0.06 


0.058 


0.01 


0.2 


0.051 


0.02 


0.019 


1.9 


0.242 


0.079 


0.02 


0.46 


0.045 


0.04 


0.06 


1.45 


0.72 


0.084 


0.04 


1.045 


0.038 


0.07 


0.12 


1.15 


1.07 


0.112 


0.07 


1.23 


0.057 


0.10 


0.18 


1.0 


1.275 


0.141 


0.10 


1.275 


0.079 


0.20 


0.33 


0.85 


1.3 


0.254 


0.20 


1.10 


0.182 


0.40 


0.58 


0.70 


1.40 


0.414 


0.40 


0.98 


0.41 


0.70 


0.82 


0.56 


1.43 


0.573 


0.70 


0.80 


0.875 


1.00 


1.00 


0.50 


1.30 


0.77 


1.00 


0.65 


1.54 



*Transfer characteristic similar to iconoscope for EI ^ 4 } Fig. II, Part I. 

Table XXI. Relative Signal-to-Deviation Ratios [R] s /[R] m ^ for 
Vidicon (71 = 0.6) and Light-Spot Scanner (7 X =1). 

Vidicon, 71 = 0.6 Light-spot scanner, 71 = 1 

/// (///)* 7^ [T~ 



0.01 


0.064 


0.33 


0.194 


0.01 


0.10 


0.20 


0.51 


0.02 


0.097 


0.77 


0.126 


0.02 


0.141 


0.46 


0.308 


0.04 


0.148 


1.74 


0.085 


0.04 


0.20 


1.045 


0.191 


0.07 


0.205 


2.05 


0.10 


0.07 


0.264 


1.23 


0.215 


0.10 


0.255 


2.12 


0.12 


0.10 


0.316 


1.275 


0.248 


0.20 


0.385 


1.84 


0.21 


0.20 


0.447 


1.10 


0.406 


0.40 


0.57 


1.64 


0.348 


0.40 


0.631 


0.98 


0.645 


0.70 


0.80 


1.34 


0.596 


0.70 


0.835 


0.80 


1.045 


1.00 


1.00 


1.08 


0.93 


1.00 


1.00 


0.65 


1.54 



150 August 1953 Journal of the SMPTE Vol. 61 



the most pleasing transfer characteristics 
are s-shaped as shown by Fig. 102 with 
a center-range gamma in the order of 1.2. 
The transfer characteristics obtained 
with linear amplifiers (y v = 1) from 
iconoscopes used for motion-picture film pickup 
or from image orthicons (studio pickups) 
are similar to that of a motion-picture 
process and will therefore be used as a 
representative standard. f For compari- 
son the amplifier gamma (y v ) for all 
other camera-tube types will be adjusted 
to result in a system gamma (JT) and a 
transfer characteristic equal to curve 1 
in Fig. 102. 

Because the video amplifier is linear 
(y v = 1), the relative-signal voltage E/E 
at the kinescope grid is directly equal to 
the relative-signal current /// from the 
camera tube. Corresponding values of 
screen luminance B/B and 72 for the 
signals E/E = I/I obtained from a repre- 
sentative kinescope characteristic (Fig. 
21, Part I) are listed in columns 3 and 4 
of Table XIX. The relative signal-to- 
deviation ratio [R],/[R]i max computed 
with Eq. (85a) for a/3 = 1, y v = 1 and 
7b = 72 is tabulated in column 5, and 
shown by curve 1 in Fig. 103. Columns 
6 and 7 of Table XIX list the point- 
gamma values of the image orthicon 
(Fig. 7, Part I) and the point gamma 
(yr) of the overall system characteristic 
curve 1 in Fig. 102. 

The signal-to-deviation characteristic 
for an image-iconoscope camera chain giv- 
ing an identical overall transfer charac- 
teristic is readily computed by tabulating 
its signal-current ratio I/I and 71 for the 
same relative exposure values EI/&I as 
listed in Table XX. The product 7,72 = 
7r/7i is then computed for the desired 
values 77- of Table XIX. The corre- 



V 
5 

< a 


- BAND 
-OVER 


WIDTH FACTO 
ALL GAMMA 1 

!"],= SLOPE 


R (A) = 


I 




























1.0 
0.8 
0.6 
0.3 
0.34 




08 
06 

04 
0.2 


3< 

6e 

16 






























i 

1 . 

< 

> 
u 
a 2 
i 

K 

z a 






















*Xx 




















/ 


Xj>T 


















^J 


^x 1 


fTa> 














> 


^ 


^ 


^ 


JO^ A 








f^ 


* 


^ 


^ 










fi 6 

> 4 



X 2 








X 
















/ 


^ 




















/" . 


? 




















/ 
















































4 4 


8 


2 468. 



t A different reference characteristic would 
not change relative performance values 
between television-camera tubes. 



RELATIVE SCREEN LUMINANCE (B/6) 

Fig. 101. Relative signal-to-deviation 
ratio of television systems having the 
same constant overall gamma and con- 
stant "flat" channel noise-level, but 
camera tubes with different constant 
gamma values. 



spending signal-to-deviation ratios are 
shown as curve 3 in Fig. 103. Table XX 
also lists the values obtained similarly for 
an orthicon or a linear vidicon camera (71 = 
1). The relative signal-to-deviation 
ratios for a vidicon with low constant 
gamma (y\ = 0.6) and a light-spot scanner 
(71 = 1) are given in Table XXI. The 
values for the light-spot scanner photo- 
tube signals require calculation of 
(///)* because of Eq. (84). The pre- 
ferred characteristic for camera tubes 
(curves 1 to 5 in Fig. 103) is that of the 
image orthicon and iconoscope (curves 
1 and 2) which is a close approach to the 
characteristic obtained from a theoretical 
constant-gamma system with a camera- 
tube gamma 71 = 0.6. The previous 
conclusion that a 71 = 0.6 is optimum 
does, therefore, not apply to a system 
with variable gamma as seen by com- 
parison of curve 5 of Fig. 103 with curve 
0.6 of Fig. 101. 



Otto H. Schade: Television Grain Structure 



151 



8 


CURV 


I DESCRIPTION 





MOTION PICTURE. B /B - 0.015 

(COMPARE PART i FIG ie) 

IM. ORTHICON CAMERA. L NEAR 
AMPLIF E.R (SEE PART I F G 17, 
CURVE C) 


IEN LUMINANCE (B/B] 



a> iu * o> 

















^ 




^ 
















2^ 


y 


















/ 


y 


? 


















y . 


/ 




















2 












RELATIVE SCR 
> 

* M * . 






-/ 


? 


7 ' 
















/ 




y 
















^ 


j 


/ 


















-^ 






















0. 


31 2 4 ' 


i 0| 2 4 6 8, 



RELATIVE EXPOSURE 

Fig. 102. Transfer characteristics of 
motion-picture and television processes. 





CURVE CAMERA TUBE TYPE 


OJ 


o PHOTOTUBE (LIGHT SPOT SCANNER) 





1 IMAGE ORTHICON E/E kne =2.3;I /I-0 


o" 


2 ICONOSCOPE F LM CAMERA 




; 3 IMAGE ICONOSCOPE 


x. 


4 ORTHICON OR VIDlCON WITH 1\- 1.0 


LJ 


5 VIDlCON, T|=0.6 


2 


TRANSFER CHARACTERISTIC 


( ^ N 


GIVEN BY CURVE 1 FIG. 102 


| 


KINESCOPE E /E = O.I3, FIG 21 PARTI 


^ 


BANDV\ 


/IDTf 


^ FACTOR (oc^'/Zrl 


o 






















\ 


K 
< 5 


















h^j 






a 

Z 4 


\ 














> 






\ 


\ 












^ 




^ 


's 


f * 


O 


\ 










^ 




f x. 


& 


" 




< 
> o 




\ 




^^ 


''^g 


^ 


' 








s 


AL 






iS-r 


r ' ^x x " 


^' 










-J a 


\ 








-'" x x 














^~ 






















^^ 






x 
















UJ 4 
























^ 
























UJ 


























01 2 468, 



RELATIVE SCREEN LUMINANCE (B/B) 

Fig. 103. Relative signal-to-deviation 
ratios of television systems using various 
camera-tube types having equal signal- 
to-noise ratios [R] m at the source and 
gamma correction to obtain the transfer 
characteristic 1, Fig. 102. 



1000 

a 
a 

4 
2 

s 

O 100 

5 


' CURVE 


DESCRIPTION 




lc 

. 2 
3 
4 
5 


PHOTOTUBE (LIGHT-SPOT SCANNER) 

HIGH-DEF NITION IMAGE ORTHICON 
TYPE 5826 IMAGE ORTHICON 
ICONOSCOPE FILM CAMERA, I m a-0.lMA 
IMAGE ICONOSCOPE, I ma = O.lfiA 
ORTHICON (C.PS. EMITRONJ, I ma z O.I/iA - 
TYPE 6198 VID CON I ma ,= 0.45/iA 


'Af=4.25 Me. N.u.^265 
-NO APERTURE CORRECTION. SEE 


TABLE SOI 


':': 
































A 
































S 






























/ 




























x 


/ 




1 
























X 


























f ' 








x^ 






t 


SIGNAL-TO-DEVIATION f 
o w 










4 




^. 


*-} 






3 


L, 










^: 


s 

^. 



= 
- 




,. * 
* * 


% 


^ 

'^ 


^ 
~f* 


^ 


^ 












^ l 








. 


/ 




















x' 


M 


<** 
























a 

4 
2 




^ 


--, 


-^ 



























































































































































































































0.01 ' 0.1 ... \0 

RELATIVE SCREEN LUMINANCE (B/B) 

Fig. 104a. Signal-to-deviation ratios at 
the screen of standard 525-line USA tele- 
vision systems using an average kine- 
scope (N e ( b ) = 265), no aperture correc- 
tion, but gamma correction to obtain the 
transfer characteristic 1, Fig. 102. 



. 

O 

2 

1 



CURVE LEGEND AS IN FIG.I04A 

Af -425 MC, N, b) -l53 

NO APERTURE CORRECTION, SEE TABLE 




. 
RELATIVE LUMINANCE (B/BJ 



Fig. 104b. Signal-to-deviation ratios in 
the retinal image for the conditions of 
Fig. 104a modified by a viewing distance 
d = 4F, which changes N e(b) to 153. 



152 



2. Signal-to-Deviation Characteristics of 
Image Frames on the Kinescope Screen 
and at the Retina of the Eye 

The signal-to-deviation characteristics 
in Fig. 103 are relative characteristics 
computed for identical transfer charac- 
teristics (curve 1, Fig. 102), identical 
signal-to-noise ratios at the source, and 
bandwidth factors (a/3)* = 1. A 
numerical comparison of image granu- 
larity requires adjustment of the [/?],- 
scale according to actually obtained 
signal-to-noise ratios [/?], and band- 
width factors (a0)* for representative 
electrical systems and succeeding optical 
apertures (A 7 ^)). The characteristics 
[/?] = f(B/B) are obtained according 
to Eqs. (84) and (85) by multiplication 
of the relative characteristics in Fig. 103 
with appropriate scale factors [R] m max /- 
(a/3)*. Electrical aperture correction 
and variation of the optical aperture 
passband N e(b ) have a considerable effect 
on the numerical values [/?], which 
differ substantially for flat- and peaked- 
channel noise sources. The relative 
magnitude and appearance of deviations 
in the retinal image vary with viewing 
distance and can be computed by includ- 
ing the aperture process of the eye in the 
value N e( b) as shown in the following ex- 
amples. 

Without aperture correction (r^ c = 7 at N c ) 
the factors m^ and cfi of the system are 
determined by the type of noise source 
(flat or peaked), the cutoff filter, and the 
equivalent passband N e(b) of the optical 
apertures following the point of noise 
insertion, while /3* is determined by 
n r and N e( b) only. The values computed 
for a standard (U.S.A.) monochrome 
television channel and a typical kine- 
scope are given in Table XXII and Figs. 
104a and 104b. When the passband 
N,(v of the optical-system apertures is 
changed, the [/^-characteristics for all 
camera chains with flat-channel noise 
sources are shifted as a group with re- 
spect to the group of [R] ^characteristics 
for camera chains with peaked-channel 
noise sources because the difference in the 



horizontal frequency spectra causes J 
to change by different factors (see Figs. 
99 to 100). The visual appearance of grain 
structures depends on the granularity of 
the retinal image which can be com- 
puted as follows. For direct-viewing 
conditions the equivalent passband #,(&> 
is the cascaded value for the kinescope 
(jV2) and the eye (N t ( eye )), which varies 
as a function of viewing distance, and 
may be obtained for an average field 
luminance of 4 to 10 ft-L from: 



N e(ev e) = 752 (V/d) (87) 

The characteristics in Fig. 104a repre- 
sent, therefore, a close viewing distance 
where N e( b) is substantially equal to the 
equivalent passband of the kinescope: 
Ne(b) Nez = 265. An increase of the 
viewing ratio to d/V = 4 changes 
Ne( e ye) to 188 and the cascaded value 
(Eq. (30b), Part II) of kinescope and eye 
to N e( b) = 153, resulting in the character- 
istics given in Fig. 104b. Before conclu- 
sions can be drawn, it is advisable to con- 
sider the effects of aperture correction. 

Aperture correction (r% c > 1 at N c ) is used 
to increase the high-frequency sine-wave 
signals from the camera tube in order to 
obtain better definition. The magnitude 
of the correction depends on the response 
of the camera tube and varies, therefore, 
for different tube types. A change of the 
high-frequency response of the video 
amplifier, however, alters its relative 
passband and the bandwidth factors m 
and a. A proper comparison of [/?]- 
characteristics from different camera 
tubes should therefore be based on the 
additional condition that the horizontal 
sine-wave response rt\r? of camera tube, 
aperture-correcting circuit, and electrical 
filter is adjusted to be substantially alike. 
The correction required for each case 
can be determined as follows. Assume 
that it is desired to obtain a response 
r$ir e equal to that of the sharp-cutoff filter 
shown in Fig. 82. This filter has a factor 
m* = 0.975. It is only necessary to 
determine the bandwidth factor a\ = 
(Ne\/N c ) h of the camera tube, locate it 



Otto H. Schade: Television Grain Structure 



153 



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154 



August 1953 Journal of the SMPTE Vol. 61 



.2 5 



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ble XXII. 

ent passband o 
d from Fi 9 
ig. 99a or 
able XXI 



CN OO 

2 2 cr cr 

- - - - 



Otto H. Schade: Television Grain Structure 



155 





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13 

3 
e 

H 
t 


o. source [J 


1 Light-spot scanner, 

/max ^ 0.01 Vi 

b Image orthicon, 5826 


c Image orthicon, 
high-definition 


> Image iconoscope, 

/max = 0.1 AW 

1- Orthicon (C.P.S. 


II 

H 

4 

1 1 

Is 


S 

ocT 

c\ 

^ . 
m 

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(r 

Values from Table XXII 
Curves and Ic correcte 


From Table XXII. 
i Electrical signal-to-noise 


8 

T-+ 

% 
fl 

% 



be 

S 
S 

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156 



August 1953 Journal of the SMPTE Vol. 61 





CURVE LEGEND 
MAX APERTURE 


AS IN FIG 104 A 
^CORRECTION. SEI 


TABLE XXm 


t 

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4 o i 2 1.0 

RELATIVE SCREEN LUMINANCE (p/6) 



Fig. 105a. Signal-to-deviation ratios at 
the screen of standard 525-line USA tele- 
vision systems using an average kine- 
scope (Ned)) ~ 265), aperture correction 
for equal horizontal sine-wave response, 
and gamma correction to obtain the 
transfer characteristic 1, Fig. 102. 

on the abscissa of Fig. 99a and read off 
the aperture correction required for the 
desired value a* = nt = 0.975. A 
tabulation of the values obtained for a 
standard television channel (N C (h) = 
340) is given in column 3 of Table 
XXIII. The various degrees of aperture 
correction alter the factors a* of the 
system following the point of "noise" 
insertion as listed in column 4 for the 
previously used apertures N e (b) = 265 
and N e (b) = 153 following the electrical 
system. The corresponding [/^-char- 
acteristics shown in Figs. 105a and 105b 
are based on equal transfer characteris- 
tics and equal horizontal response in a 
standard television channel with n r = 
490 and N c(h) = 340. 

A comparison of the signal-to-deviation 
characteristics of a standard 35mm mo- 
tion-picture projection (Fig. 57b, Part II) 
and television images of similar quality 
is given in Table XXIV and Figs. 106a, 



1000 




4 


CURVE LEGEND AS IN FIG I04A 
A<-=4.25 MC. N._I53 

MAX. APERTURE CORRECTION, SEE TABLE Tr^T 
.REF "REFERENCE CHARACTERISTIC-FOR 6=10 FT.-L.! 
(SEE TEXT) 
































































1 






























L, 


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s / 




























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too 


























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SIGNAL -TO-DEVIATION f 
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o.i .^ 

RELATIVE LUMINANCE (8/6) 

Fig. lo") I). Signal-to-deviation ratios in 
the retinal image for the conditions of 
Fig. 105a modified by a viewing distance 

d = 4F. 



106b, and 106c. It will be shown in 
Part IV that a 30-frame television system 
having n, = 625 lines and a video pass- 
band A/ = 8 me is adequate to duplicate 
35mm motion-picture performance. This 
performance can be obtained only with 
high-quality signal sources, maximum 
aperture correction and high-quality re- 
producers (Nez = 400). The perform- 
ance of all camera-tube types, however, 
has been computed for comparison. The 
[^-characteristics Fig. 106a represent 
conditions at the screen and Figs. 106b 
and 106c at the retina of the eye for the 
viewing distances d = 2.5V and 4V re- 
spectively. The motion-picture charac- 
teristic in Fig. 106a is the [/?] p -charac- 
teristic shown in Fig. 57b of Part II. At 
a viewing distance d = 2.5V the equiva- 
lent passband of the eye is N e(evt) = 300 
(Eq. (87)). In cascade with the equiva- 
lent passband N e ( P ) = 370 of the motion 
picture, the overall system passband be- 



Otto H. Schade: Television Grain Structure 



157 



100 

a 


.CUF 
A-f = 
MAX 


VE 
8 
. A 
35 


L 

PE 

^M 


EC 
RT 


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MO 


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AS 

too 
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ECTION 
CTURE 


104 




A 

(P) 


FABl 
370, 


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6 

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10 

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SIGNAL-TO-DEVIATION ( 

M * 




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RELATIVE SCREEN LUMINANCE 



Fig. 106a. Signal-to-deviation ratios at 
the screens of 35mm motion-picture and 
625-line theater-television systems (A/ = 
8 me) having the transfer characteristics 
in Fig. 102, a television projector with 
JV e (6) = 400 and high aperture correction 
to provide equivalent sharpness (see 
text). 

comes TV^e(s) = 233. The motion-picture 
characteristic in Fig. 106b is obtained 
with [] s = [R] p (370/233) and in Fig. 
106c with [#] s = [R] p (370/188) be- 
cause in these cases the relative amplitude 
distribution in the deviation spectrum 
and the products [/?] p JV e ( S ) remain sub- 
stantially constant (see p. 22, Part II). 
The characteristics in Fig. 106 show that 
in the medium and light tone range the 
motion-picture frames have larger devia- 
tions (lower |7?] s ) than the television sys- 
tems curves 0, lc and 5, but that the 
granularity of the motion picture is lower 
in the shadow tones. 

With increasing viewing distance, the 
signal-to-deviation characteristic of the 
aperture-corrected television systems im- 



2 
100 


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A-F 
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= 8 
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35 

.-R 

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MOTIO 
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OR 
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RECTIC 
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0.01 2 4 O.I 2 4 * * I.C 
RELATIVE LUMINANCE (s/B) 



Fig. 106b. Signal-to-deviation ratios in 
the retinal image for the conditions of 
Fig. 106a modified by a viewing distance 

d = 2.5V. 



4 


'CURVE LEGEND AS IN FIG. I04A 
:A*- = 8Mc, N . tb ,= 70 
MAX. APERTURE CORRECTION, SEE TABLE ! 
M.R 35MM MOTION PICTURE (N, (I) = IC8) 

REF.=REFERENCE CHARACTERISTIC FORB=IOFT.-L 
(SEE TEXT) 


























// 


S'OO 
























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\ 
\ 


MP 
















s 


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.-* 


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M 


1 


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RELATIVE LUMINANCE (B/B) 

Fig. 106c. Signal-to-deviation ratios in 
the retinal image for the conditions of 
Fig. 106a modified by a viewing distance 

d = 4V. 



158 



August 1953 Journal of the SMPTE Vol. 61 



proves more rapidly than that of the 
motion picture. It must also be borne in 
mind that the signal-to-deviation ratios 
evaluated for the motion picture are 
values that neglect all defects and 
scratches which noticeably increase the 
deviation level in the film projection 
above the ideal values after relatively few 
runs, as borne out by measurements of the 
noise level from the sound track of 
motion-picture film. There is no paral- 
lel degradation in live-television systems, 
because every showing is a "first" show- 
ing. The signal-to-deviation character- 
istics of the theater-television systems 
using the high-definition image orthicon 
(Fig. 95), light-spot scanners, or the 
type-6198 vidicon are, therefore, satis- 
factory in comparison with motion pic- 
tures. The definition obtained with the 
type-6198 vidicon, however, is not 
equivalent to 35mm motion pictures. 

3. Equivalent Passband (jV e(s) ) and 
Sine-Wave Amplitudes 

Amplitude distribution and A^-values 
for the sine-wave spectrum of the devia- 
tions in a television frame can be com- 
puted accurately from the products of 
corresponding response factors for the sys- 
tem elements following the noise source. 

The sine-wave response of a particular 
combination of elements can be approxi- 
mated with good accuracy by one of the 
normalized characteristics given in this 
paper. The analysis of the intensity dis- 
tribution in the vertical coordinate (Eq. 
(57) and Fig. 70) has shown that the 
television raster may produce a carrier 
wave containing a series of sine-wave 
components with fixed amplitudes. 
These constant carrier components are 
not included in the total energy of the 
deviations. When the deviations orig- 
inate in electrical elements, the vertical- 
frequency spectrum is in all cases that of 
the aperture db following the electrical 
elements (see section C2). The sine- 
wave response of theater-television sys- 
tems (not including camera) is illus- 



trated in Fig. 107. The response factors 
are by definition the amplitudes obtained 
with a normalized sine-wave energy in- 
put into the theoretical television chan- 
nel, i.e., for an rms noise input voltage 
[] m = 1 . The equivalent passbands in 
the horizontal and vertical coordinates 
have been related to the theoretical pass- 
band by bandwidth factors; W<*) = 
aNc and N e ( V ) = /3n r to permit evaluation 
by normalized characteristics. The 
equivalent passband (N e (,)} of the sys- 
tem is computed with Eq. (68) (see 
Tables XXII to XXIV). f While the 
response factors in the horizontal and 
vertical coordinates are independent of 
one another, the actual amplitudes of the 
sine-wave flux components of the devia- 
tion flux are not, because the total sine- 
wave deviation energy P = c^Nc is inde- 
pendent of direction. For a normalized 
deviation "output" energy P 1, the 
amplitude scale factor is therefore c = 
JV~s for symmetrical apertures, and the 
amplitude distribution Y(N) = /(#) is 
obtained by multiplying the response 
factors r$ by the scale factor: 

rp - r*C#.)- (89) 



(90) 



Similarly for television systems: 

Y (N )h = rf( h ) C( h ) = rf (h )(aN c ) 
and 



The relative amplitude characteristics 
corresponding to Fig. 107 are shown in 
Fig. 108. The characteristic of the 35mm 

f Because of aperture correction the value 
JV e ( a) does exceed the theoretical value 
JV e(m) considerably for the condition N e ( b) 
= 400 in Table XXIV. This abnormal 
condition exists for deviations only and it 
should be remembered that an equivalent 
passband is by definition a "flat" passband 
which would contain the same total devia- 
tion energy. The system response to sine- 
wave components in picture signals is nor- 
mal, because it includes the decreasing 
response of the camera tube. 



Otto H. Schade: Television Grain Structure 



159 



Ne(b)=400| HORIZONTAL 

N e(b )=240J' RESPONSE 

VERTICAL RESPONSE 

ALL SYSTEMS 



CURVE* 


(Ne(b)/Nc) h 


FIG. 


0,l c 
Ib 
3,4,5 


0.745 0.447 
ii II 
u ii 


86c 
86d 
9lc 




0.5 1.0 1.5 

RELATIVE LINE NUMBER[(N/Nc)K] ; N c = 537 

Fig. 107. Sine-wave response factors of theater-television 
and motion-picture systems for the conditions of Figs. 106a and 
106b. 



160 



August 1953 Journal of the SMPTE Vol. 61 



Fig. 108a. Relative am- 
plitudes of sine-wave spec- 
tra for equal-energy signals 
and deviations at the screen 
of theater-television and 
motion-picture systems. 



35mm MP. HOR. & VERT. SPECTRUM 
TV SYSTEMS, HOR. SPECTRUM 
TV SYSTEMS, VERT. SPECTRUM 




400 
LINE NUMBER 



000 



Fig. 108b. Relative am- 
plitudes of sine- wave spec- 
tra for equal-energy signals 
and deviations at a viewing 
distance d = 2.5 V from the 
screen of theater-television 
and motion-picture 
terns. 



sys- 



.08 



|.06 



r 

.02 



MP 

V 

0-5 



DESCRIPTION 



35mm MP, HOR. & VERT. SPECTRUM 
TV SYSTEMS, VERT. SPECTRUM 
TV SYSTEMS, HOR. SPECTRUM 




200 400 

LINE NUMBER 



motion picture in Fig. 108a is that of 
Fig. 59, Part II, normalized for P = 1 
by multiplication with c = 370 ~* = 
0.0518, and by c = 233~* = 0.0653 for 
Fig. 108b, which represents conditions at 
the retina for a viewing distance d = 
2.5V. 

The visual appearance of the grain 
structures in motion-picture and televi- 
sion frames is indicated by the amplitude 
spectra (Fig. 108) for equal signal-to- 
deviation ratios. The vertical spectra are 
substantially identical and the prepon- 



derance of low frequencies indicates a 
soft grain structure. The horizontal tele- 
vision spectra for "flat" channel devia- 
tions (0, Ib, \c) have a somewhat smaller 
and sharper appearing grain size. The 
"peaked" channel deviations (3, 4, 5) 
containing no low frequencies and hav- 
ing maximum energy at a fairly high 
line number (N = 400 to 500), have a 
smaller and more uniform appearing 
grain size. 

This interpretation of the amplitude 
spectra may be compared with the grain 



Otto H. Schade: Television Grain Structure 



161 



Figure 109 is on plate pages 118 and 119. 



structure photographs shown in Fig. 109 
which were taken under somewhat 
similar conditions in a 4.5-mc system for 
the purpose of measuring the deviation 
ratio in an image frame by sampling with 
a physical aperture. The linear dimen- 
sion of the samples in Fig. 1 09 is approxi- 
mately one-fourteenth of a picture frame. 
The samples A, B and C are photographs 
of "peaked" channel, "flat" channel, and 
35mm motion-picture grain structures 
respectively. In the top row (index 1) 
are single-frame grain structures ob- 
tained with small apertures db showing 
the raster line structure of the television 
samples A and B. The middle row (2) 
illustrates the condition for a larger aper- 
ture db for all 3 cases. This aperture was 
given a value to produce a "flat field" 
in the television frames and equal the 
spot size of the supercinephor lens for 
C2. Note the longer grain size in the 
vertical direction of A2 which is evidence 
of the flat-frequency spectrum across the 
raster even from a peaked "noise" 
source, which causes positive- and nega- 
tive-grain doublets in the horizontal co- 
ordinate due to the absence of low fre- 
quencies and the differentiated pulse 
shape shown in Fig. 93. The samples 
A3 and B3 show the effect of superimpos- 
ing the grain structures of six television 
frames by a photographic exposure of ^ 
sec. The deviations were increased in 
magnitude to show more clearly that the 
grain doublets have practically dis- 
appeared in A3 due to random super- 
position. 

4. Discussion of Results 

Examination of the various signal-to- 
deviation characteristics shows clearly 
that the theoretical signal-to-noise ratios 
[R] m max (Table XVII) is not an ade- 
quate measure of camera-tube perform- 
ance. It is evident from Tables XXII 



and XXIII that the electrical signal-to- 
noise ratios [R]$ max which can be meas- 
ured in the video-transmission link, may 
also differ substantially from the theoret- 
ical value [R] m max, because for compa- 
rable definition the sine-wave response of 
the camera tube is reflected in the degree 
of aperture correction and alters the 
sine-wave amplitudes in the frequency 
spectrum of the deviations. 

Aperture correction increases the noise 
level by a factor which is larger for 
peaked-channel noise than for flat- 
channel noise, as illustrated by the value 
of the electrical factor m* in Table XXIV 
for conditions Ib and 3, for example. 
The filtering action of succeeding aper- 
tures has an opposite effect, reducing 
the deviation level (!/[/?]) and granu- 
larity of the retinal image by a larger 
factor for peaked-channel noise than for 
flat-channel noise. These factors are 
given by the ratio of corresponding fac- 
tors a* which, according to Table XXII, 
is 0.665/0.4 = 1.66 in favor of peaked- 
channel noise without aperture correc- 
tion and at a viewing distance d = 4V 
from a standard 525-line television 
image, f When moderate aperture cor- 
rection is used the ratio decreases (see 
Table XXIII) and with high aperture 
correction it approaches unity (see 
Table XXIV) and may even reverse. It 
therefore appears desirable to specify the en- 
tire signal-to-deviation characteristic in the 
retinal image for a given viewing distance. 
To judge the entire characteristic it is 
necessary to establish a reference charac- 
teristic based on the perception of random 
deviations as a function of luminance. 
Subjective observations as well as fun- 



f This value is considerably lower than the 
ratio given in the author's earlier paper. 3 
The earlier values are in error because they 
are ratios of bandwidth factors (a) rather 
than factors (a?}. 



162 



August 1953 Journal of the SMPTE Vol. 61 



damental considerations 6 - 7 indicate that 
the visual perception of fine detail and 
granularity is limited at low luminance 
values by random fluctuations in the 
visual process and at medium and high 
luminance values by the aperture re- 
sponse of the optical system of the eye 
(see, for example, Fig. 83). From an 
objective point of view, perception of 
fluctuations from an external source 
(image) in the low luminance range 
occurs when the total deviation from 
both external and internal sources ex- 
ceeds the internal deviations of the visual 
process by a barely perceptible amount 
which can be assumed related to a visual 
sensation unit. When the optical and 
photoelectric characteristics of the eye 
are known, the ratio of the two deviations 
may be calculated as a function of lumi- 
nance by the method outlined in this 
paper. The evaluation of an analog sys- 
tem for the visual process based on data 
from subjective observations appears 
possible and of considerable value for an 
objective analysis. This will be discussed 
in Part IV. 

For the present it is sufficient to refer 
to such observations, which indicate 
that the signal-to-deviation ratio in an 
external or retinal image required to give 
threshold visibility, is nearly constant for 
luminance values (B) above 10 ft-L, and 
decreases for values less than 10 ft-L. 
The luminance values of motion-picture 
and theater-television projections fall into 
this lower range. For use as a reference 
standard the exact vertical location of 
the threshold curve for the eye is not 
important, unless one is specifically inter- 
ested in threshold values, f Shape and 
approximate location of the reference 
characteristic are shown in Figs. 106b 
and 1 06c, for a highlight brightness B = 



t It is noted that observations on the per- 
ception of fluctuations in television pictures 
made at luminance values above 10 ft-L 
are not likely to apply directly to the lower 
luminance values of theater television and 
motion pictures. 



10 ft-L. It is noted that the image- 
orthicon curves Ib and Ic have a fairly 
uniform vertical distance to the reference 
characteristic, which means that percep- 
tion of their grain structure is fairly uni- 
form, decreasing towards the ends of the 
range. The shape of the motion-picture 
characteristic (MP) indicates that its 
grain structure will appear most per- 
ceptible at B/fc ^ 0.4 but is invisible in 
the deep shadow tones. 

Referring now particularly to Fig. 
106b which represents conditions at the 
close viewing distance of 2.5 times the 
vertical screen dimension, it can be seen 
that graininess in the systems represented 
by curves 5 and MP will be perceived 
with similar intensities but in a differ- 
ent part of the luminance range. Simi- 
larly, when comparing curves \ e and 
MP, and it is evident that the motion 
picture will appear more grainy in the 
upper half of the tone range than the 
television picture which exhibits a nearly 
uniform graininess over the entire range. 
At the more normal viewing distance of 
d = 4V represented by Fig. 106c, the 
characteristic of the motion picture is 
positioned for the most part much farther 
below the threshold-reference character- 
istic than those of the television systems 
0, 5 and Ic, which now appear in general 
less grainy than the motion picture. 
Considering furthermore that the mo- 
tion-picture characteristic is representa- 
tive of an ideally "clean" film it can be 
concluded that the graininess of theater- 
television images, such as are represented 
by curves 0, \c and 5 in particular, will 
compare favorably with that of 35mm 
motion pictures. 

The evaluation of deviations of elec- 
trical origin in television frames has 
shown that television systems may be 
designed to have a performance sub- 
stantially equal to a 35mm motion- 
picture system. Because of the similar 
frame rate, the storage factor s and 
signal-to-fluctuation ratios in "live" 
television pictures are not materially 
different from those of motion pictures. 



Otto H. Schade: Television Grain Structure 



163 



A camera tube with adequate signal out- 
put and definition such as the experi- 
mental high-definition image orthicon 
(curve \c in Fig. 106, and Table XXII 
is required for a theater-television system 
having a granularity comparable to that 
of a 35mm motion picture using plus X) 
negative and fine-grain positive film 
(1302). The theoretical value [R] n max 
at the source for this type of camera tube 
corresponds to an electrical noise level 
of -38.8 db, or -41.3 db including syn- 
chronizing signals. The noise level in 
the video-transmission system (corre- 
sponding to [/?] 3 = 43.4) is 32.7 db, 
or 35.2 db including synchronizing sig- 
nals. To prevent impairment of this 
performance, the noise level of the trans- 
mission system itself should be approxi- 
mately 6 db better, or both the trans- 
mission system and the camera tube 
should have noise levels 3 db lower than 
stated above. 

A more accurate statement can be 
made when the amplitude distribution in 
the frequency spectrum of the additive 
noise is known. Statistical tests of 
signal-to-deviation ratios by the sam- 
pling of television grain-structure photo- 
graphs on 4 X 5-in. film have been in 
good agreement with computed values. 
The above method has also been applied 
to compute the noise levels reported by 
Pierre Mertz in two publications. 8 - 9 In 
view of the estimates which had to be 
made for a number of unspecified system 
constants the calculated values appeared 
to be in satisfactory agreement with the 
reported values. 

Many relations between apertures and 



their sine-wave response characteristics 
as well as characteristics of vision have 
only been indicated and will be discussed 
in more detail in Part IV of this paper. 

References 

1. Pierre Mertz and T. Gray, "The theory 
of scanning and its relation to the char- 
acteristics of the transmitting signal in 
telephotography and Television," Bell 
Sys. Tech. J., 13: p. 464, 1934. 

2. I. C. Gardner, "A new resolving power 
test chart," (abstract), J. Opt. Soc. Am., 
40: 257, Apr. 1950. 

3. O. H. Schade, "Electro-optical charac- 
teristics of television systems, Part III 
Electro-optical characteristics of camera 
systems," RCA Rev., 9: 490-530, Sept. 
1948. 

4. P. Schagen, H. Bruining and J. G. 
Francken, "The image iconoscope a 
camera tube for television," Philips 
Tech. Rev., 13: 119-133, May 1951 (ab- 
stracted in Jour. SMPTE, 58: 501-514, 
June 1952). 

5. W. A. Harris, "Fluctuations in vacuum 
tube amplifiers," RCA Rev., 5: 505-525, 
Apr. 1941; ibid., 6: 114-124, July 1941. 

6. O. H. Schade, "Electro-optical charac- 
teristics of television systems, Part IV 
Correlation and evaluation of electro- 
optical characteristics of imaging sys- 
tems," RCA Rev., 9: 653-686, Dec. 1948. 

7. A. Rose, "Television pickup tubes and 
the problem of vision," Advances in 
Electronics, I: 133-166, Academic. Press, 
New York, N.Y., 1948. 

8. Pierre Mertz, "Perception of television 
random noise," Jour. SMPTE, 54: 8-34, 
Jan. 1950. 

9. Pierre Mertz, "Data on random noise 
requirements for theater television," 
Jour. SMPTE, 57: 89-107. Aug. 1951. 



164 



August 1953 Journal of the SMPTE Vol. 61 



Photographic Instrumentation 
of Timing Systems 



By A. M. ERICKSON 



Time-action marking at film speeds from 2000 to 8000 frames/sec and some 
of the circuit requirements which must be met to obtain clear edge marks 
on motion-picture film are discussed. 



A HOTOGRAPHIC timing has become 
necessary in the field of instrumenta- 
tion. Primarily time is correlated with 
an action on motion-picture film. It 
gives facts about that action which 
otherwise cannot be obtained. For 
instance, timing on motion-picture film 
has been used to study velocity, acceler- 
ation, oscillation (pitch and yaw), 
vibration and position of projectiles in 
flight. The same photographic system 
has been used to gather data about 
explosive trains, shock waves and a 
variety of other high-speed action 
phenomena. 

Under conditions which dictate the 
use of high-speed cameras we have 
found that neon gas ionization is one of 
the most serviceable methods of film 
marking. It has been chosen in pref- 
erence to argon gas ionization, spark 
gaps and field-of-view devices for general 
use at the Naval Ordnance Laboratory 



Presented on October 9, 1952, at the 
Society's Convention at Washington, D.C., 
by A. M. Erickson, Naval Ordnance 
Laboratory, White Oak, Md. 
(This paper was received April 30, 1953.) 



for the following reasons: (a) neon will 
mark color film with good contrast 
(this is not so for argon gas) ; (b) neon 
is not affected by atmospheric conditions 
as in the case of spark gaps, and is 
relatively simple from a voltage stand- 
point; (c) field-of-view timers consume 
valuable picture space and are subject 
to focus and lighting conditions which are 
not always the same as that of the subject. 

The Naval Ordnance Laboratory has 
fitted many of its cameras with neon 
timing lights and has attempted to 
standardize on the NE-51 bulb, a recent 
addition to the neon family. 

To excite neon gas for clear edge 
marking it is necessary to produce a 
pulse of at least 90 v. A duration of not 
less than 8 /*sec and the power to main- 
tain voltage during ionization is also 
necessary. The "work horse" timing 
system (shown in Figs. 1 and 2) more 
than meets these minimum require- 
ments. It consists of three units, an 
oscillator, a pulse generator and a six- 
channel cathode follower. 

The oscillator is a battery-powered 
fork with good stability which delivers 



August 1953 Journal of the SMPTE Vol. 61 



165 




Fig. 1. Pulse timing system and neon timing light mounted on upper sprocket 
clamp of an Eastman High-Speed Camera. 



about 25 v to a high-impedance load. 
Its output is used only to control the 
repetition rate of the pulse and is de- 
pendable under a variety of field 
conditions. 

The a-c powered pulse generator, 
which is controlled by a stable-fre- 
quency source, is independent of voltage 
and frequency variations of the power 
line. For operation of only one camera 
this generator is connected directly to 
the camera marking light. 

To time up to six cameras a six- 
channel cathode-follower amplifier sys- 
tem is used. This unit when driven 
directly by the pulse generator develops 
marking pulses on six separate circuits. 
Each light is given its own individual 
circuit mainly for insurance. It has 
been found that neon bulbs exhibit high 
firing potentials after considerable use, 
some measuring above 100 v, as com- 
pared with 75 v for new bulbs. If several 
used bulbs are placed across the same 
circuit, and the combined load limits 



peak-pulse voltage to 90 or 100 v, an 
old bulb may not fire, or it may fire 
erratically and give false timing in- 
formation which is more detrimental 
than no timing at all. Many field tests 
are conducted specifically for the photo- 
graphic results. The total cost of test 
operations may range from $100 to 
$40,000 a day with complete destruction 
of the ordnance material under test. 
In the face of such expensive operations 
it is unwise to design borderline features 
into instruments which add .to this 
expense. 

Each cathode-follower output circuit 
is equipped with a current-meter switch 
and a variable-series resistance. Ex- 
posure current, a predetermined value 
of approximately 1 ma (average), is 
adjusted by varying the series resistance. 
This provides an indication of proper 
intensity regardless of line length, and 
proof that the exposure light is func- 
tioning. This facility of remote test 
and exposure adjustment is valuable in 



166 



August 1953 Journal of the SMPTE Vol. 61 



PULSE 
GENERATOR 




SIX CHANNLL 
CATHODE. FOLLOWER 



Caihodt 
Follower 




To Neon Bulb 

In Camera 



Fig. 2. (Above) Pulse timing system. (Below) Detail of the 
pulse timer output circuit. 



both time and labor to the photographer 
when his cameras are spread over a long 
firing range or at the top of range 
towers. 

In addition to time marking, some 
instrumentation requires "start-action 
marks" on the film to indicate when 
an event takes place, such as the break- 
ing of a wire, the closing of a firing key, 
or the attainment of certain water 
pressures. When action begins with the 
firing of a detonator by electrical means, 
it is better to tap the firing circuit for 
start information if it is possible. Any 
electrical connection made to firing 
circuits other than those necessary to 
fire the detonator are considered a 
safety hazard and precautions must be 



taken to eliminate prematures. The 
circuit shown in Fig. 3 will not only 
provide a pulse of the proper impedance 
and polarity but will fire the detonator 
and under certain circumstances provide 
bias to gate a timing circuit closed until 
start marking has taken place. 

When a double-pole relay is used 
with a firing circuit over one set of 
contacts, and a pulse circuit over the 
other, error will always result when 
trying to close two sets of contacts at 
the same time. This error is usually of 
the order of a few milliseconds even 
though both sets of contacts are on the 
same relay, and cannot be depended 
upon for accurate or close timing. The 
Naval Ordnance Laboratory system 



Erickson: Timing System? 



167 



To Camera Switch 



~* Firing 

Bott. 



^ 



1 10 VAC. 



Bait. 



InjecW Into 
Puls. Gn. 



I I 
Ammeter 

Fig. 3. Diagram of start-marking system for marking motion-picture film 
at instant firing key is closed. 



Oscill ator 



.0001 1/ \- 1.8 M 
( *-7 




Fig. 4. Portable battery-powered pulse timer designed for field use, incorporating 
magnetic amplifier principles to shape the timing pulse. 



168 



August 1953 Journal of the SMPTE Vol. 61 



uses one set of contacts to close both 
circuits. In stand-by condition two 
batteries are connected in parallel 
through the detonator and a large re- 
sistance. A charging or discharging 
current will flow between two identical 
batteries until both batteries are of the 
same terminal voltage. Even the most 
sensitive primers will stand 100 pa 
without damage to the squib wire. 
A microammeter is available to test any 
lack of voltage balance prior to connect- 
ing the primers in the circuit. 

The start-mark circuit is connected 
to the grid of a voltage-amplifier stage 
in the pulse generator as shown in Fig. 
2. It delivers a pulse with a delay 
time governed by R and C of Fig. 3. 
This results in a film which contains a 
start mark injected into the regular 
timing pulses. A disadvantage from a 
data reduction point of view is that 
interpolation is necessary to determine 
the time interval between the start mark 
and the next timing mark. 

One of the main sources of trouble in 
field instrumentation originates from 
field power supplies. When these 
supplies are furnishing power to both 
high-speed cameras and timing equip- 
ment, a peak load caused by camera 
"start up" momentarily disables the 
timing equipment and results in a loss 
of timing marks during the action 
period. A completely battery-powered 
timer is useful under these conditions. 
The timer must be stable and should 
develop enough power to meet the pre- 
viously mentioned requirements. These 
features are incorporated into a new 
design which uses magnetic-amplifier 
principles for wave shaping (see Fig. 4) . 

The circuit generates a stable sine 
wave, power-amplifies this sine wave 
and converts the wave into a pulse. 
The oscillator is an RC-controlled feed- 
back circuit with good stability. It has 
been constructed as a plug-in unit to 
change frequency by changing the 
entire oscillator. The second stage 
operates as a class "A" amplifier and 



develops power to drive the pulse-shaping 
circuit. The shaping is done by passing 
the sine-wave current through a satur- 
able reactor. As the core is driven 
into saturation the reactor loses its 
inductance and transfers its inductive 
voltage drop to the series resistance 
R-l. The sudden decrease in load 
resistance causes condenser C-l to 
"dump" its excessive charge through R-l 
and causes a still further increase in 
voltage. The net result is sharp pulses 
of about 50 v developed across a rela- 
tively low impedance. These pulses 
plus a d-c bias make up enough voltage 
to fire neon timing lights. The pulses 
appear across terminals #1 and #2. 
The pulse and the bias may be obtained 
without additional components by con- 
necting the marking bulb across termi- 
nals #2 and #3. This places the first 
battery of the "B" supply in series 
aiding with the output pulse. 

Timing marks without an associated 
picture can also be useful under certain 
conditions. In the development of an 
arming vane for a missile, instrumenta- 
tion was needed to determine angular 
velocity and acceleration of the vane 
under flight conditions. The problem 
was solved by the simplest kind of 
pulsing circuit (see Figs. 5 and 6). The 
recorder consists of a photographic film 
rotated by the arming vane. As the 
film turns, a pulse-driven exposure 
light marks the perimeter of a disk to 
give time-motion characteristics at the 
rate of approximately one mark every 
25 msec. With a 100:1 step-down gear 
ratio, and an assumed vane speed of 
6000 rpm, the film disk was estimated 
to make not more than 1 rps. This 
spaces the timing marks about 9 apart 
when the vane is rotating at its maximum 
estimated speed. 

"Start" and "stop" switches are 
placed on the outside of the missile, 
while all other components are fitted 
in the booster cavity. One switch puts 
the circuit into operation just before 
launching, and the other disables it 



Erickson: Timing Systems 



169 




Fig. 5. Rocket arming-vane tinier which mounts in a rocket case. The timer marks 
a rotating disk of film to record the velocity and acceleration of the arming vane 
during flight. Left to right: film-disk housing; circuit shelf; batteries. 



~^A 
Fuse 


1.6 M 




Ei'iV 




y sup 


NEH6, 






Switch 


".08 




Switch 






Fig. 6. (Left) Schematic of the basic RC-pulsing circuit installed in the rocket booster 
cavity. Start and stop switches are mounted on the outside of the rocket case. 
(Right) Diagram of time-recorder test film; one space equal to 23.8 msec. 



T^ ' ;.r\ . L_yi4.yT\ \ \ \ \a;\ n 7 ^rnTY\-> i , ' 
^ \ V\-V,\ iT^ti' \ \ HT:' '' '"V.H V* -'; ' 






|*_Tf 



3H1 



i- i- 1 i 

ON J.MVHO 



r ("1^7 I T f f 

"' 






Fig. 7. Photograph of a permanent frequency record made by connecting a Brush 
Pen Recorder across the battery terminals of Fig. 6. This record is made just prior to 
rocket launching. Paper speed, 5 in. /sec; pulse rate, 42/sec. 



170 



August 1953 Journal of the SMPTE Vol. 61 



MY + 




One Shot 
Muliivi'brator 



Fig. 8. Diagram of a delay timer designed to trigger 
photographic spark stations in a ballistics range. 



during flight after the record has been 
taken. Although the system is used at 
slow film speeds, it can have application 
in high-speed work if the pulse rate is 
increased. The waveshape is not a 
pure pulse, in the sense that it has both 
a steep rise and fall, but its firing 
characteristics are such that the lamp 
receives a maximum current at the 
instant of ionization and decreases at 
the RC discharge rate until lamp- 
extinction voltage is reached. This 
results in maximum exposure at the 
leading edge with a fading trail behind 
it, and furnishes a sharp edge as a 
reference point on each mark. 

The frequency of this generator is 
dependent upon the characteristics of 
every component in the circuit and stray 
capacity of the circuit to ground. Fre- 
quency measurements were made by 
amplifying voltage-notches appearing 
directly across the battery terminals. 
Connection to any other point in the 
circuit gave erroneous readings because 
of added load or wiring capacity of 
the measuring equipment. Amplified- 
voltage notches are recorded as shown 
in Fig. 7 on a Brush Pen Recorder just 
prior to launching. This provides a 



permanent frequency record for data 
reduction. 

The completed unit was tested in the 
~ simulation laboratory at an acceleration 
of 25 gravitational units. This more 
than exceeded acceleration forces ex- 
perienced by the unit under launching 
conditions. No noticeable change in 
fundamental frequency was measured 
after the "G" test. 

Timing circuits are quite useful in 
ballistics-range work to trigger micro- 
second spark lights in photographic 
stations along a range. An antenna 
or pickup unit placed slightly ahead of 
each photographic station senses the 
passage of a projectile and fires a spark- 
light source down range to obtain a 
shadowgraph of the projectile as it 
passes through the station. 

In order to do this an electronic delay 
timer is necessary to receive the sensing 
information, hold it for a predetermined 
period of time, and then emit a signal 
to fire the spark light. A timer which 
will perform these tasks is shown in 
Fig. 8. The first part of the circuit 
forms an oscillator which reacts only 
when it receives the "sensing" signal. 
It is a "one-shot" multivibrator and 



Erickson: Timing Systems 



171 



has most of its application in radar as a 
gating or pulsing circuit. The delay 
time is dependent upon values of RC- 
coupling components which have been 
made variable in this circuit to cover 
the range of delays needed to match 
projectile velocity. 

A missile traveling at 3000 fps takes 
about 660 jusec to move 2 ft between 
the sensing antenna and the photo- 
graphic plate. The sensing antenna 
immediately pulses the delay circuit to 
start it timing. The one-shot multi- 
vibrator, 610 jusec later, sends a pulse 
to the trigger tube which has a normal 
delay of approximately 50 /isec. To- 
gether the two delays make up a re- 
quired total of 660 jusec and fires the 
main spark light just as the projectile 
is in position for exposure. The trigger 
tube in a stand-by condition is drawing 
its maximum current and holds the 
auxiliary spark-gap voltage to a mini- 
mum. Application of the pulse causes 
the tube to cut off and allows full- 
supply voltage to reach the auxiliary 
gap and fire the main discharge gap. 

This high-voltage type of circuit can 
easily be adapted to function as a start- 
marking system in high-speed motion- 
picture cameras. It can be used by 
placing the spark gap in a camera as an 
auxiliary to the regular timing light, 
or it can be connected to the camera 
frame on one side and the spark allowed 
to jump to one of the leads of a neon- 
bulb marking light. This method of 
start marking does not load the regular 
timing circuit and can delay marking 
action for convenience in data reduction 
or for correlation with other camera 
records taken of the same action. Also 
it can be used as the regular timing 
system to furnish both timing marks 
and start marks. If a fixed bias instead 
of a pulse is applied to the circuit at the 
instant of starting, the film will receive 
a series of marks spaced in time accord- 
ing to the delay time of the circuits. 
Data reduction still depends upon a 
measurement ahead of the first timing 



mark to find the start mark because the 
delay timer receives the start information 
but does not give it out for one cycle. 

Discussion 

Robert D. Shoberg (White Sands Proving 
Gd.): I assume you had trouble firing the 
NE-51 lamp in total darkness. How did 
you overcome that? 

Mr. Erickson: There was no trouble at all 
as long as we exceeded the firing potential. 
The regular firing potential of a new bulb is 
around 75 v. In darkness I don't know 
what it is. We usually apply about 125 v 
across a circuit impedance of not more than 
1000 ohm. 

Mr. Shoberg: We tried that, and had a 
lot of trouble. Finally we discarded the 
equipment we were using and put in the 
Fastax timing system, using an NE-51 
lamp. 

Mr. Erickson: We have had absolutely no 
trouble in firing as long as we get above 
125 v. An old bulb, remember, will have 
an increase in firing potential. 
Mr. Shoberg: We aged the lamps. 
Mr. Erickson: How much power did you 
use? What kind of circuit did you use to 
drive it? 

Mr. Shoberg: Up to 125 v. We have a 
very elaborate timing system there, but we 
ran into the same problems you did. We 
checked before we ran and everything was 
going fine. We opened the door of the 
camera and the lamp was not glowing. 
We closed the door and made the test 
and the film came out blank. The lamp 
would not start in total darkness at the 
same voltage it would in the dark. 

Mr. Erickson: We have had no trouble. 
Mr. Shoberg: You solved the problem by 
increasing the voltage on the lamp? 

Mr. Erickson: Yes. That takes care of it 
every time. 

Mr. Shoberg: It was not practical for us to 
increase the voltage to that extent so we 
substituted the NE-66 lamp for the NE-51 
lamp. This eliminated our trouble as the 
NE-66 fires at considerable lower voltage 
than the NE-51. 



172 



August 1953 Journal of the SMPTE Vol. 61 



Gerald Doughty (Aberdeen Proving Gd.): 
We ran into the same thing. We are using 
about 65 v d-c bias, with a pulse about 22- 
/isec duration and 120-v amplitude above 
bias. The bias serves to keep the bulbs 
ionized without producing enough light to 
affect the film traveling at low speeds. 
Failures of time records practically dis- 
appeared. Line-voltage drop due to heavy 
current loads from camera runs affects this 
system less than any other we have tried. 
Bulb life is about 10-min operating time, or 
approximately 200 Fastax runs. 

Mr. Erickson: Regardless of the pulse 
height? 

Mr. Doughty: That is right. We have no 
trouble from film fogging. The bulbs do 
get old, and sometimes too old before we 
change them. But generally they work 
pretty well. 

Mr. Erickson: I don't think we have ever 
had a bulb fail because of its old age. 

Major P. Naslin (French Laboratory of 
Armaments): Would it be possible to make 
your vibrator-timer insensitive to a very 
intensive discharge, say 200 wsec within one 
fjisec, which involves very high terms in the 
order of several thousands. 

Mr. Erickson: I don't know what you 
mean by making it insensitive. Do you 
mean in the proximity? 

Major Naslin: From being triggered. 

Mr. Erickson: The idea is to have the 
timer not trigger when this high current is 
flowing? 

Major Naslin: Nearby. 

Mr. Erickson: If it reaches the circuit, it is 
bound to make the multi-vibrator operate. 
If you make the input impedance of that 
circuit low enough, regardless of what this 



other thing is doing, it won't affect the 
vibrator, because it responds only to the 
bias or signal on the first stage. If this bias 
is raised high enough, the circuit will go 
into oscillation. 

Major Naslin: Have you done it? 

Mr. Erickson: Yes, I have. When we 
were designing this equipment for the 
Naval Ordnance Laboratory pressured 
range, the circuit that I showed you (Fig. 8) 
was considered in the final photographic 
station. This photographic station setup 
required the projectile to be charged by a 
20,000-v source, and there was a lot of high 
voltage around near the trigger circuit. 
We had a common feed source for the high 
voltage which goes down the range to 
charge each of the spark-light condenser 
units also located near the trigger circuit. 
The discharge of the first spark light, 
which is a sudden drain and a very high 
current flow, can affect the sensing antenna 
on the following station and make it start 
timing before it is supposed to. We over- 
came that by merely decreasing the imped- 
ance of the circuit being affected. Of 
course, proper shielding and grounding are 
necessary. 

Follow-up of the Discussion 

(Submitted by the author, April 30, 1953): 
In answer to questions about firing poten- 
tials the author has conducted a series of 
tests on 10 NE-51 neon bulbs picked at 
random. They were placed in a lighted 
room and individually connected to a d-c 
voltage with a time constant of 10 sec, that 
is, 10 sec were required to raise the voltage 
from to 150 v. Firing potentials for the 
bulbs ranged from 70 to 76.5 (see Table I). 



Table I. Firing-Potential Data Taken on 10 New NE-51 Neon Bulbs (Firing-Potential 

in Volts). 



Bulb No. 


1 


2 


3 




4 


5 


6 


7 


8 


9 


10 


Daylight 
3 min dark 
24 hr dark 
3 month 
dark 
2d try 


75.0 
78.5 
80.0 
99.0 

77.0 


71.5 
81.0 
120.0 
95.0 

73.0 


72 
74 
125 
113 

78 


.0 
,5 
,5 





81.0 
93.5 
107.0 
105.0 

86.0 


70.5 
90.5 
115.0 
98.0 

72.5 


71.5 
83.5 
117.0 
125.0 

81.0 


76.5 
91.0 
124.0 
90.0 

77.0 


74.0 
79.5 
150 + 
72.0 

72.5 


74.5 
84.0 
150 + 
100.0 

75.0 


73.0 
81.0 
78.5 
90.0 

75.0 



Erickson: Timing Systems 



173 



After 3 min of darkness the same bulbs ex- 
hibited ignition potentials between 78.5 
and 93.5 v. After 24 hr of darkness two 
bulbs failed to fire with up to 1 50 v. on the 
first try. The remaining eight bulbs fired 
between 78.5 and 125.5 v. The two that 
did not fire broke down at 74.0 v and 109.5 
v on the second try. After 3 months of 
darkness the firing potentials ranged from 
72 v to 125 v with no failures. Firing all 
bulbs the second time decreased the range 
from 72.5 to 86 v. 

Some conclusions can be drawn from 
these tests: (1) NE-51 bulbs are light 
sensitive; (2) firing potentials are generally 
higher in the dark than they are in the 
light; (3) successive application of voltage 
causes a random decrease in firing poten- 
tial with a lower limit being the daylight- 
firing voltage of that specific bulb; and (4) 
for start-marking action a pulse in excess of 
150 v must be applied for reliable results. 

Contrary to popular belief, a pulse gener- 
ator designed to drive neon timing lights 
must have the characteristics of a power 
circuit, not just voltage amplification. A 
timing light represents a changing load 
according to its conditions. When fired it 
represents a very low resistance and the 
driving circuit must be designed to deliver 
ample current through this low resistance 
and still maintain pulse voltage in excess of 
bulb-firing voltage. 



Therefore the generator output should be 
of the cathode-follower type, rather than a 
plate-loaded circuit. Power tubes such as 
the 6L6, 6V6, 6Y6 and 6AS7 with proper 
circuit connections will solve most timing- 
light problems. 

Discussion of NE-51 Lamp 

(Prepared by H. M. Ferree, General Electric 
Co., Nda Park, Cleveland, May 7, 1953): It 
has long been known that glow lamps such 
as the NE-51 do have a definite "dark 
effect." When the lamp must be enclosed 
in a light-tight enclosure such as a camera, 
the starting voltage of the lamp may be 
increased as much as 20 to 50 v, d-c. 

The test data presented by Mr. Erickson 
agree reasonably well with our experience, 
and the solution he offers, namely increas- 
ing the applied potential well beyond the 
normal starting voltage, has in most cases 
proven to be the simplest and most satis- 
factory. 

Also, the time required for ionization is 
reduced as the voltage in excess of normal 
starting is increased. In some applica- 
tions this may be a determining factor. 

As Mr. Erickson points out, the starting 
voltage of a glow lamp increases with age. 
Therefore, where there are no other limiting 
conditions on the applied voltage, voltages 
in excess of the 150 he mentions might be 
used to extend the usefulness of the lamp. 



174 



August 1953 Journal of the SMPTE Vol. 61 



The M-45 Tracking Camera Mount 



By MYRON A. BONDELID 



A new, versatile tracking camera mount is described. This instrument was de- 
veloped to solve certain problems in ballistic data-gathering activities. Per- 
formance and operational characteristics of the mount, camera types and uses, 
lenses, communication, orientation, timing and power requirements are also dis- 
cussed. The tracking camera mount is a completely independent unit, supply- 
ing its own power, and capable of negotiating heavy sand. 



A 



THE U.S. Naval Ordnance Test 
Station, Inyokern, China Lake, Calif., a 
new, versatile tracking camera mount has 
been developed to solve certain problems 
known as "attitude" in ballistic data- 
gathering activities and to provide an 
easy method to track fast-moving ob- 
jects. 

Testing of rockets and guided missiles 
must be done under dynamic conditions 
in which the component is allowed to 
function under normal environmental 



Presented by abstract only on October 10, 
1952, at the Society's Convention at Wash- 
ington, D. G., and in full on May 1, 1953, 
at the Society's Convention at Los Angeles, 
by Myron A. Bondelid, U. S. Naval Ord- 
nance Test Station, Inyokern, China Lake, 
Calif. 
(This paper was received on April 3, 1953.) 

This paper is published for information pur- 
poses only. It does not represent the official 
views or final judgment of the Naval Ordnance 
Test Station, and the Station assumes no respon- 
sibility for action taken on the basis of its con- 
tents. The M-45 Tracking Camera Mount has 
not yet been fully developed and several changes 
mentioned in this report might occur differently 
in the final form. It is being developed under 
Task Assignment No. TP 872-H. 



conditions. The recording of the neces- 
sary test data becomes a difficult task 
under these conditions since no direct 
mechanical contact with the test object 
is possible when it is in free flight. 

Bell & Howell Eyemos and Superspeed 
Cameras comprised the bulk of the early 
photographic recording test equipment, 
but it was realized early that the exacting 
demands required of the data recorded 
left much to be desired. As this was a 
special need, little equipment could be 
utilized as manufactured, and physicists, 
engineers and photographers pooled 
their knowledge and experience to adapt 
or devise instruments that could better 
meet the rigid requirements of deter- 
mining trajectory, velocity, acceleration, 
attitude and other data necessary to 
evaluate scientifically the performance of 
rockets and missiles under test. 

Trajectory, velocity and acceleration 
are determined by the Askania Cine- 
theodolites and Bowen Ribbon-Frame 
Cameras. Attitude is often determined 
from the Askania, but because of image 
size, quality and frame rate this is usually 
insufficient. Therefore attitude, which 



August 1953 Journal of the SMPTE VoL 61 



175 




Fig. 1. The M-45 Tracking Camera Mount powered by a 20-kw 3-phase 208-v a-c 
diesel generator located on *he prime mover (Official Photograph) U.S. Navy). 



includes pitch, yaw and roll, missile- 
booster separation, off-range deflection, 
launching, time of flight and detailed 
motion are usually determined from 
Mitchell, Fastax, or other high-speed 
cameras. 

A basic approach to the problem of 
measuring attitude is to take photographs 
of the missile from at least two positions 
with motion-picture cameras equipped 
with long focal-length lenses so that the 
pictures will be large and easily meas- 
ured. The apparent angle of the missile 
with respect to each camera reference 
system is measured and these data are 
then mathematically converted to atti- 
tude angles with respect to the range co- 
ordinate system. 

Attitude measurements determine the 
orientation of the missile at a predeter- 
mined sampling rate. The orientation 
measures are classified according to their 
relationship to the line-of-flight axis of 
the missile. Roll or spin describes rota- 
tion about this axis, while pitch and yaw 
describe the vertical and horizontal com- 
ponents of transverse oscillations of the 
missile about its center of gravity. 

In the design and subsequent rede- 
sign of a test missile it is necessary to 



know the aeroballistic characteristics of 
the missile ; attitude in flight is the chief 
of these characteristics and is an impor- 
tant piece of information on the flight 
of a missile. 

In the past the Mitchell Chronographs 
were mounted on heavy-duty tripods and 
hand tracked with the aid of an auxiliary 
optical system. Lenses of 17- to 20-in. 
focal lengths were used with these cam- 
eras. As emphasis on attitude measure- 
ments increased, and the desire for more 
accurate data developed, longer focal- 
length lenses became a necessity. How- 
ever, the longer lenses required more ac- 
curate tracking, and soon it was realized 
that a mechanical means was needed to 
track fast-moving objects. 

As a result of tests conducted at NOTS, 
an Army model M-45 50-caliber ma- 
chine-gun mount was acquired and used 
as the tracking mechanism. After 
some alterations and additions (such as 
removing the machine guns and install- 
ing cameras and lenses) the M-45 
Tracking Camera Mount, popularly 
known as the "Gooney Bird," emerged. 

Early versions of the "Gooney Bird" 
were mounted on an M-20 trailer. Power 
was received from batteries on the mount 



176 



August 1953 Journal of the SMPTE Vol. 61 




Fig. 2. Cameraman operating M-45 Tracking Camera Mount 
(Official Photograph, U.S. Navy). 



and separate generators powered the 
cameras. 

The latest version of the M-45 is shock- 
and spring-mounted on an M-l Tandem 
Trailer with stabilizing jacks and leveling 
provisions. A refractor of 48-in. focal 
length is mounted on one side of the 
operator and a half-scale version of this 
same lens is mounted on the other side. 
Pictures for attitude purposes are re- 
corded by means of a 35mm Mitchell 
Chronograph Camera. A 1 6mm Mitch- 
ell Pictorial Camera may be used for 
documentary movies or a Fastax camera 



for super slow-motion studies. Each 
"Gooney Bird" is powered by its own 
generator system, which is mounted on a 
2^-ton 6X6 truck used as the prime 
mover for the M-45, and is thus a com- 
plete, independent unit capable of nego- 
tiating heavy sand encountered in the 
Mojave Desert (Fig. 1). 

Performance and Operational 
Characteristics 

The elimination of footwork around a 
tripod and the ease and speed of control 
of the M-45 have resulted in an appreci- 



Bondelid: Tracking Camera Mount 



177 



able gain in missile-tracking rate. Per- 
formance of the M-45 is very satisfactory 
when it is in good condition. In field use 
it is difficult to maintain optimum per- 
formance over sufficiently long periods. 
Tracking rates of 60 deg/sec are attain- 
able in order to have a margin of safety 
beyond the experienced maximum rates 
of approximately 40 deg/sec. In track- 
ing it is important that the tracking rate 
be similar to the speed of the missile to 
prevent blurred images which are dif- 
ficult to measure. Acceleration charac- 
teristics are generally satisfactory, al- 
though some decrease in acceleration in 
elevation has been observed after some 
use. It is easier to track a fast-moving 
object in elevation only, without the azi- 
muth component. 

Chatter in elevation causing double 
images and the loss of tracking perform- 
ance, both due to the old large-diameter 
ball bearings, have been eliminated by 
installing new tapered roller trunnion 
bearings. The present azimuth roller 
bearing is satisfactory and capable of 
smooth operation when clean, but it is 
poorly sealed and maintenance requires 
the disassembly of the mount. 

The turret structure contains all of 
the rotatable supporting elements of the 
mount. The trunnions which carry the 
lens, camera and binoculars are mounted 
to elevate through an arc of 10 to 
+ 90 from the horizontal. The turn- 
table, upon which the trunnions are 
mounted, rotates through 360. The 
operator's seat, which does not move in 
elevation, is centralized in the mount 
structure and is tilted backwards about 
45 to permit coverage of the full eleva- 
tion range. The seat is adjustable so that 
the operator may regulate his position in 
order to follow the sight with minimum 
head movement (Fig. 2). 

The mount movement and camera 
operation are controlled from a pair of 
control handles through a mechanical 
linkage mounted on a column which is 
straddled by the operator and within easy 
reach of his hands. The control handles 



may be moved in a vertical or horizontal 
arc or in a combination of both. The de- 
gree of movement and position of the 
handles control the speed and direction 
of the mount. Off-On switches, one 
mounted on each side of the control 
handles, actuate relays in the junction 
boxes which carry power to the cameras. 

Camera Types and Uses 

Instrumentation used on the M-45 is 
shown in Fig. 3. The 35mm high-speed 
Mitchell Chronograph Camera (Type 
B), which utilizes the 48-in. lens, is used 
to obtain the bulk of the required atti- 
tude data. This instrument combines 
the advantages of timing, large image, 
high speed and high tracking rate on the 
M-45. 

The Mitchell Chronograph was de- 
signed with the cooperation of the U.S. 
Navy to meet special photographic re- 
quirements of the service. It is an inter- 
mittent-type, 35mm motion-picture cam- 
era. In order to insure the accuracy and 
precision required, the mechanism is 
manufactured to extremely close toler- 
ances. The term "high-speed" is derived 
from the fact that the camera will operate 
at any speed up to 128 frames/sec using a 
110-v a-c/d-c electric motor. A 12-v d-c 
motor is available for lower speeds. 

A chronograph head with a 1/100-sec 
stop watch attaches directly to the 
specially designed camera base and 
photographs the image of the chronom- 
eter onto a corner of the frame on the 
emulsion side of the film utilizing the 
camera shutter. 

The 16mm Mitchell Pictorial Camera, 
which utilizes the 24-in. lens, is used for 
documentary purposes only. This cam- 
era is similar to the 35mm Mitchell 
Chronograph except that it is not 
equipped with provisions for timing, 
and uses 1 6mm film. 

The 16mm Eastman High-Speed and 
8mm or 1 6mm Wollensak Fastax cameras 
(24-in. lens) are used to study detailed 
motion, separation of booster from the 
missile, time to action, and launching of 



178 



August 1953 Journal of the SMPTE Vol. 61 




Fig. 3. Instrumentation used on M-45. Left to right, top row: Berkeley Time 
Interval Meter, 35mm Mitchell Chronograph with 48-in. lens in front, 16mm Mitchell 
Pictorial with 24-in. lens in front, 16mm Bell & Howell, 16mm Eastman High-Speed; 
bottom row: photoelectric Cell, 16mm Fastax, 8mm Fastax, 35mm Fastax (Official 
Photograph, U.S. Navy). 



missile. These cameras are designed for 
high-speed photographic work with ex- 
posures ranging from 500 frames/sec to 
3000 frames/sec in the EHS and up to 
14,000 frames/sec in the 8mm Fastax. 

Both of these cameras are of the con- 
tinuous-film-drive type. A rotating 
optical flat is used to displace the image 
by an amount equal to the film move- 
ment during exposure. This system al- 
lows sufficient exposure, with reasonable 
definition, despite the fact that in some 
cases the film may be running through 
the camera at 200 fps. The effective 
operating time of these cameras ranges 
from approximately 0.75 sec to about 9 
sec, depending on the frame speed. 

Timing is provided by means of timing 
lamps built into these cameras receiving 
their pulses from a broadcast 1000-cycle 
pulse. 

The 16mm Bell and Howell 70 TA 
Camera (Northrup modification) is used 
in place of the EHS and Fastax to study 
detailed motion, separation of booster 
from missile, and launching of missile. 



Normal operating speed is 200 frames/- 
sec which is sufficient for most high-speed 
work and eliminates problems connected 
with prism- type cameras. This camera 
gives higher resolution due to an inter- 
mittent-type motion, and a longer re- 
cording time due to a slower frame speed. 

A photoelectric cell has been used in 
conjunction with the 24-in. lens to time 
an event from launching to burst. 

Ansco color film is widely used on all 
attitude cameras to aid in distinguishing 
the image on film. The high-speed 
cameras have given acceptable results up 
to 500 frames/sec. Missiles have been 
painted with highly reflective and 
fluorescent colors to increase their con- 
trast against the blue sky. The most suc- 
cessful colors have been Fire Orange, 
which also aids immeasurably in visual 
tracking, and Saturn Yellow. 

Lenses 

The increased emphasis on attitude 
measurements pointed up the need for 
better lenses for the M-45 Tracking 



Bondelid: Tracking Camera Mount 



179 



Camera Mounts. At first a 40-in. Bausch 
& Lomb Telestigmat //8 lens was tried. 
Because it was meant to cover a large 
film rather than the 35mm frame size 
the resolution was poor and hence not 
suitable for our use. Very long focal- 
length lenses have been used with some 
measure of success, but much of the more 
recent developmental work on attitude 
cameras has concentrated on lenses of 
more conservative focal lengths with ex- 
ceptional image quality. 

Two such lenses are now in use on all 
M-45 Tracking Cameras: the 48-inch 
//8 Thompson refractor lens, especially 
designed to cover the 35mm frame, and a 
half-scale version of this same lens, de- 
signed to cover the 16mm frame. The 
lenses were designed by Kenneth B. 
Thompson of the Thompson Optical 
Laboratory, Pasadena, Calif., and manu- 
factured by Aaron J. Otto of Pasadena. 

Thompson utilized air-spacing in the 
elements of the doublet as another de- 
gree of freedom for greater correction. 
This also does away with objectionable 
cemented surfaces which must be recon- 
ditioned often. The lens is sealed to 
guard against the entry of dust and is 
mounted in a cell which can be easily 
secured to the lens tube by four screws. 

The front element glass is made of 
Borosilicate Crown-2 with an index of 
refraction n D = 1.51700, the rear surface 
glass of Dense Flint-4, n D = 1.64900. 
The effective focal length is 48 in. d= 
0.25 in., the back focus is 0.989 times the 
focal length, and the diameter is 6.000 
in., making the stop constant at//8. 

The elements are made from striae- 
free glass and the polished surfaces are 
coated for anti-reflection. Under the 
Foucault (autocollimated) knife-edge 
test, the lens shows uniform shadow with 
no evidence of axial astigmatism. The 
lens is corrected for longitudinal chro- 
matic aberration for infinity focus. 
There is no turned-down edge figure and 
the test glass patterns were symmetrical 
to one-quarter fringe. Kenneth B. 
Thompson wrote that the design had 



exceeded his fondest expectations and 
compared the lens with the Rayleigh- 
Conrady tolerances as follows : 

Rayleigh- Residual 

Conrady Aber- 

Aberrations Tolerances rations 

Marginal 

Spherical 

(4X/sinV) 0.02367 in. 0.00164 in. 
"Zonal Spherical 

(6X/sin 2 a') 0.033 in. 0.0011 in. 
Saggital Coma 

( X/2 sin a ') . 0001 8 in. . 00009 in. 

(X is 0.000022 in. and sin ' is |- //no.) 

Performance tests made on the 24-in. 
lens show by visual observation that it is 
capable of resolving about 200 lines/mm 
on the optical axis and 100 lines/mm at 
the extreme edge of the field of a 1 6mm 
frame. The superb performance of the 
48-in. lens has been aptly demonstrated 
by the resolving on film of tree branches 
at a distance of 1 5 miles. 

The lens, as has been stated above, is 
mounted in a cell which can be easily 
secured to the lens tube by four screws. 
The lens tube has a metal shield protect- 
ing it from the sun, and after the lens is 
in place a lens shield 1$ ft long further 
protects the lens. The camera, rather 
than the lens, is focused by means of a 
smooth-riding platform suspended by 
ball bushings and actuated by a rack 
and pinion. This method of focusing, 
developed at NOTS, permits optimum 
focus of the lens with comparative ease. 

Orientation 

The accuracy of pitch, yaw and roll 
measurements depends to a large extent 
on the levelness of the M-45. At low 
elevation angles the effect of a level error 
may introduce an error in yaw measure- 
ments of twenty times the level error it- 
self. By orienting the M-45 immediately 
before or after an event it is possible in 
assessing the data to adjust the error. 

At several permanent stations where 



180 



August 1953 Journal of the SMPTE Vol. 61 



the M-45's generally are located are 
three red-and-white striped telephone 
poles placed 90 apart at a radius of 
about 1 mile. At the top and bottom of 
each pole targets are located very ac- 
curately to indicate perpendicularity. 
The operator takes short bursts of film 
on each pole. 

To determine the out-of-levelness of 
the M-45 the film is assessed by placing 
cross-hairs on the targets and along the 
edge of the film and the angle deter- 
mined. The correction to be applied to 
the assessed data can be computed from 
these measurements. 

Timing 

Timing for the 35mm Mitchell 
Chronograph is accomplished by photo- 
graphing the projected image of a 1/100- 
sec 3-sec sweep stop watch or a 1/100-sec 
single-sec sweep electric clock onto a cor- 
ner of the frame on the emulsion side of 
the film utilizing the camera shutter. 
Zero time of missile firing is indicated by 
a flashbulb at the launcher. The 16mm 
Mitchell Pictorial has no provision for 
timing. In the future the 35mm 
Mitchell will record time by means of a 
binary counter in place of the stop watch 
or electric clock. 

The Fastax and Eastman high-speed 
cameras record timing by means, of 
broadcasted pulses. The APR-13 trans- 
mitter, a modified version of a "tail 
warning type of radar," is used for put- 
ting the timing marks on the edge of the 
rapidly moving film. The frequency of 
the transmitter is 400 me. As now used 
it is a pulse-modulated transmitter using 
1000-cycle and 200-cycle synchronized 
pulses. At the receiver, which is a modi- 
fied APS-13 receiver, the pulses light 
neon bulbs. The antenna for the re- 
ceiver is a folded dipole. 

Zero time of missile firing is indicated 
on the edge of the film by the start of the 
1000-cycle pulses, the 200-cycle pulses 
being on continuously. Also, the 200- 
cycle pulse is of longer duration, thus 
making a larger mark on the film edge. 



The range of the transmitter is ap- 
proximately 5 miles and at the present 
time is being increased to about 10 miles 
with a new NOTS design of transmitter. 

In the case where the M-45 is too far 
from the broadcasted pulses, a 1000- 
cycle "pulse generator" (NOTS de- 
signed and constructed) is used. Zero 
time from the pulse generator is indicated 
by the start of the 4-cycle pulse used by 
Askanias and other instrumentation. 
The 1 000-cycle pulses from this generator 
are not synchronous with the broad- 
casted 1000-cycle pulses at Fire Control. 

In the Fastax and EHS cameras an 
NE51 neon bulb is used. The pulse 
amplitude to the neon is approximately 
1 80 v. No resistor is used in the circuit 
due to the high brillance of the neon 
necessary to show on the high-speed film. 
A special holder designed at NOTS is 
used to place the neon bulb in close 
proximity to the film. 

At the present time no provision has 
been made for timing on the Bell & 
Ho well 70 TA Camera. 

In the case where a missile detonates in 
the air or around a target, a photoelectric 
cell will record the change in light in- 
tensity on an oscillographic record which 
was started when the missile was 
launched and recorded the 1000-cycle 
pulses, thus timing an event quite accu- 
rately. 

Communications 

The communication equipment for the 
M-45's consists of two identical sets of the 
Navy Type TCS-12 transmitter and re- 
ceiver. One set is located on the M-45 
itself and operates from the batteries 
through a 12-v d-c dynamotor power 
supply. This enables the operator to 
listen to a count-down over earphones or 
small speaker located close to his ear and 
to report coverage while seated in the 
mount. The other set, located within the 
trailer, is equipped with a large speaker 
and operates from a TCS-AC 110-v 
power supply. It is a stand-by radio to 
conserve batteries and is used to carry 



Bondelid: Tracking Camera Mount 



181 



necessary traffic such as warnings and 
progress of preparation previous to an 
actual event. 

This equipment is primarily used on 
MHF in general ground range com- 
munications between the master control 
station, mobile units, and M-45 opera- 
tors. 

A VHF BC 639 receiver with an a-c 
power supply is also used for the monitor- 
ing of aircraft frequencies when aircraft 
tests are being conducted. 

Power Requirements 

The 21-ton General Purpose 6X6 
International Truck is used as the prime 
mover for the M-45 Tracking Camera 
Mount. A 20-kw, 3-phase, 208-v, a-c 
diesel generator is mounted on the rear 
of the truck and supplies the power for 
the mount, cameras and communications. 
Each "Gooney Bird" is thus a complete, 
independent unit capable of negotiating 
heavy sand and able to move into any 
position desired. 

The power drive on the mount con- 
sists of a Maxson variable-speed drive 
with a 12-v d-c electric motor. On 
several mounts, two 6-v batteries furnish 
the power to drive the turret structure 
and to power the communications on the 
mount. On one mount a 12-v d-c recti- 
fier system has been added in place of the 



batteries and operates from the genera- 
tor. Already placed into production are 
plans for operating the mount by a 3- 
phase, 208-v a-c motor and providing 
all M-45's with a slip-ring assembly to 
operate all equipment on the turret 
structure. 

The power requirements for the M-45 
hence include 3-phase, 208-v a-c for the 
mount to permit tracking in azimuth and 
elevation, 110-v a-c for the Mitchells, 
EHS, communications and timing, and 
250-v d-c for the Fastax. 

Conclusion 

Attitude has taken an important role 
in the evaluation of the flight of a missile 
ever since the first caveman fashioned 
his spear and hurled it at his enemy. 
Scientists need an accurate method to 
determine the aeroballistic characteristics 
of a missile to develop it to the highest 
possible standards of perfection. The 
M-45 Tracking Camera Mount, though 
only an interim measure, has proven its 
worth in obtaining data that would have 
been impossible using hand tracking 
methods and inadequate lenses. 

Though improvements are continually 
being made on the "Gooney Bird," it is 
not to be construed that it is the best or 
final solution to the problems encoun- 
tered in the science of rocket photogra- 
phy. 



182 



August 1953 Journal of the SMPTE Vol. 61 



Fundamental ProblemsofSubscriptionTelevision: 
the Logical Organization of the Telemeter System 

By LOUIS N. RIDENOUR and GEORGE W. BROWN 



The general problem of encoding a picture for transmission and decoding it 
at the receiver is considered, with special reference to the privacy problem of 
subscription, or pay-as-you-see television. Alternative ways of indicating 
the price of the program and acknowledging its payment are described. The 
factors which have led to the choice of system elements made in the Telemeter 
system become clear on the basis of this general discussion. 



O INSCRIPTION television is the name 
that has been given to a system for broad- 
casting television programs in such a way 
that a person desiring to view the pro- 
gram being transmitted must pay for the 
privilege, precisely as he would pay 
admission to a theater, stadium or other 
place of entertainment where such a pro- 
gram might be offered. This is not the 
place to debate the wisdom or desira- 
bility of subscription television, although 
it may be worth noting that the entertain- 
ment world is faced with a difficult 
financial problem posed by the broad 
public acceptance of television enter- 
tainment. Advertising sponsors of tele- 
vision programs cannot pay the pro- 
ducer of entertainment a sum consistent 
with what he has been accustomed to 
obtain by offering his entertainment in 



Presented on April 28, 1953, at the Society's 
Convention at Los Angeles, by Louis N. 
Ridenour (who read the paper) and George 
W. Brown, International Telemeter Corp., 
2000 Stoner Ave., Los Angeles 25, Calif. 
(This paper was received April 30, 1953.) 



return for the payment of an admission 
fee by each individual patron. Total 
costs of television programs amount to 
sums less than five cents per viewer of the 
program; yet the total budgets repre- 
sented by this modest cost per head are 
growing so large that most advertising 
sponsors are meeting them only with 
some difficulty. 

A scheme which enables each viewer 
of a television program to pay a rela- 
tively modest "admission" fee would 
make possible much higher budgets for 
such special programs, with a consequent 
improvement in the quality of program 
material. It is largely for this reason 
that the proponents of subscription tele- 
vision systems are striving to develop 
effective schemes for making "pay-as- 
you-see" television practicable. 

The Problem of Secrecy 

Perhaps the most fundamental prob- 
lem in subscription television is that of 
providing suitable means for rendering a 
broadcast television program private. The 
very contradiction in terms of the last 



August 1953 Journal of the SMPTE Vol. 61 



183 



| SCENE 



ENCODER 
AND 
TRANSMITTER 


BRIGHTNESS INFO x 


RECEIVER 


SYNC. SIGNALS ^ 




* 



-DISPLAY 



KEY SIGNALS IMPLICIT IN 
KNOWN STANDARD CONVENTIONS 
DEFINING CODE 



Fig. 1. Conventional television. 



phrase illustrates the difficulty of doing 
this. 

To begin with, we notice that the 
transmission of any intelligence, includ- 
ing the visual and aural signals involved 
in television, requires a coding of that 
intelligence into a form that is suitable 
for transmission (Fig. 1). The receiving 
apparatus then decodes the received 
signal and reconstructs from it the in- 
telligence which was encoded at the 
transmitter. In the case of television, 
the coding scheme which has been 
adopted in this country is only one of a 
large number of possible coding schemes, 
any one of which might reasonably have 
been standardized. Indeed, in Europe 
and parts of South America different 
coding schemes have in fact been chosen. 
The successful reproduction of broad- 
cast television programs depends upon 
the standardization, in transmitters and 
in receivers, of agreed coding conventions 
that will be adhered to. 

Some of the conventions which are in 
current use are as follows : 

(1) Elements of the scene to be trans- 
mitted are scanned in two interlaced 
fields per frame of 525 lines; 30 frames 
are scanned per second. 

(2) The brightness of a picture ele- 
ment is represented in analog fashion by 
the amplitude of a quasi-single-sideband 
carrier on a scale from to 75% of full 
carrier power; white is represented by 
zero, black by 75%. 

(3) Synchronizing pulses of standard 
form, duration and location with respect 
to the video information are transmitted 



in the range from 75 to 100% of visual 
carrier power. 

These conventions and others which 
govern the transmission of aural informa- 
tion are, of course, well known. They are 
mentioned here only to point out some 
ways in which nonstandard coding of 
television transmissions can be used to 
render a transmission "private" in the 
sense that acceptable reproduction of the 
visual and aural intelligence being trans- 
mitted cannot be accomplished by a 
standard receiver whose design is based 
upon the standard conventions. 

A point of some importance arises 
here. Once the conventions for stand- 
ard coding of television transmissions 
have been settled, it is then the goal of the 
receiver designer to build a receiver 
which will give adequate reproduction of 
picture and sound when these conven- 
tions are used and, in effect, will have 
nothing to spare. Competition in terms 
of price is so important that the well-de- 
signed receiver will have very little capa- 
bility outside of the conventions of trans- 
mission and reception for which it has 
been designed. This means that, when 
we depart from those conventions in 
order to transmit a subscription television 
program, the nature of our departure 
from the accepted standards of transmis- 
sion and reception will determine the 
amount and complexity of the auxiliary 
equipment required at the receiver to 
enable it to reproduce good pictures and 
sound under the novel conditions. Qual- 
ity of program reproduction is, if any- 
thing, more important in subscription 



184 



August 1953 Journal of the SMPTE Vol. 61 



television than it is in ordinary television. 
The subscriber, having paid for the pro- 
gram, will expect to receive picture and 
sound of good technical quality. 

The agreed coding conventions for 
television immediately suggest a variety 
of ways in which the coding scheme can 
be changed. The standard line scan can 
be replaced by a different scanning raster ; 
this may consist of an altered number of 
lines per field, of fields per frame, or both. 
It may involve bizarre sorts of scan such 
as spirals, to-and-fro zigzags, or other pat- 
terns; or perhaps an alteration in the 
order in which lines are scanned in a 
given field. The representation of bright- 
ness can be modified in various ways. 
The simplest is perhaps an inversion of 
the analog brightness scale, so that the 
picture transmitted is related to a stand- 
ard transmission as a photographic 
negative is related to a positive. Alter- 
natively, various digital schemes for in- 
dicating the brightness of a picture ele- 
ment can be imagined. The conventions 
regarding synchronizing signals admit 
of a rich variety of possible variations. 
The synchronizing signals can be sup- 
pressed or changed in form, or a change in 
the time relationship between the syn- 
chronizing signals and the scanning ac- 
tions which they are to produce can be in- 



troduced. There are many other possible 
schemes for altering the convention under 
which television signals are encoded, and 
there is no point in discussing them ex- 
haustively here. 

Note that while we have talked only in 
terms of encoding and decoding the 
visual information, similar considerations 
apply to the encoding and decoding of 
the aural transmissions which accompany 
the picture signals. 

Rather than discussing the relative 
merits of various specific nonstandard 
forms of coding, it will be useful to com- 
plete this discussion of the secrecy prob- 
lem by dealing briefly with the manner 
in which the security of any private tele- 
vision transmission can be maintained 
inviolate. It is clear at the outset that no 
single choice of a nonstandard code, how- 
ever elaborate may be the differences be- 
tween it and the standard transmission 
convention, will insure the privacy that 
is desired. The persistent use of a single 
code will provide time for analysis of the 
coding method and the consequent con- 
struction and use of unauthorized de- 
coders. 

Neither can it be assumed that per- 
manent privacy for coded transmissions 
can inhere in the constructional details 
of the decoder mechanism itself. It must 



BRIGHTNESS INFO 




PROGRAM PRICE AND 
IDENTITY INFO. FROM 
ANOTHER SOURCE; EG. 
NEWSPAPER. T 



PRICE INFO. AND PROGRAM 

IDENTIFICATION 

(POSSIBLE, BUT NOT INCLUDED 

IN ORIGINAL SCHEME) 



Fig. 2. The original Phonevision proposal. 
Ridenour and Brown: Subscription Television 



185 



be supposed that any decoding attach- 
ment which can be manufactured 
cheaply and in large numbers can also be 
readily duplicated by unauthorized 
people. 

There remain two ways in which the 
privacy of the coded transmissions can be 
maintained. The first is represented, for 
example, by the so-called Phonevision 
system of subscription television (Fig. 2) . 
A private channel for electrical commu- 
nications between each subscriber and a 
central office is postulated in this scheme ; 
because the cost of installing a special 
channel especially for subscription tele- 
vision would be entirely prohibitive, the 
use of telephone lines was originally pro- 
posed. The private communication 
channel is used for the transmission of 
signals which control the action of the de- 
coder, upon indication by the subscriber 
concerned that he wishes to purchase the 
subscription program being broadcast. 
Without these signals, even a decoder of 
the sort used in the Phonevision system 
will not successfully decode the coded 
transmission. It is characteristic of this 
scheme, which we might refer to as a 
"closed system," that the necessary 
secrecy for the decoding process is pro- 
vided by the existence of a private com- 
munications channel between the sub- 



scriber and the encoding center which 
controls the nature of the transmission. 

Such a closed system is straightfor- 
ward and has much to recommend it. In 
particular, the decoding attachment 
which must be added to the subscriber's 
receiver is likely to be simpler in the case 
of the closed system than it is in the case 
of the open type of system which we shall 
discuss in a moment. Unfortunately, the 
closed system suffers from the profound 
difficulty that the private channels of 
communication which it requires repre- 
sent a vast capital investment on the part 
of some utility system. Any realistic as- 
sessment of the charges which should be 
made for the use of such channels to pro- 
vide subscription television yields the re- 
sult that such a closed system is very ex- 
pensive to operate. There are other 
practical difficulties, such as the demand 
this system would make on the central- 
office switching facilities of the telephone 
system, but this is not the place to con- 
sider them. 

Another form of closed system has been 
proposed under the name "Subscriber- 
Vision" (Fig. 3). In this system the sub- 
scriber himself cooperates in providing 
the secure channel for decoding informa- 
tion. This is accomplished through the 
physical transport of a code card or other 



PHYSICAL TRANSPORT 
OF CODE CARD 
BY SUBSCRIBER 




KEY SIGNALS PROVIDED BY 
CODE CARD WHEN 
SUBSCRIBER INSERTS 
IT IN DECODER 



PAYMENT BY 
SUBSCRIBER 



186 



Fig. 3. The original Skiatron proposal. 
August 1953 Journal of the SMPTE Vol. 61 



physical code device; such code cards 
would be prepared with the necessary in- 
formation to decode certain future trans- 
missions, and then distributed to various 
points of sale in the communities where 
subscription television programs on this 
scheme were to be offered. A subscriber 
wishing to purchase a series of programs 
would purchase the corresponding code 
card at a point of sale, take it physically 
to his television receiver, and insert it into 
the decoding unit attached to his re- 
ceiver. The decoding unit will be ac- 
tuated in the proper fashion only when 
it has been provided with the code card 
appropriate to the program being broad- 
cast. 

Provided that the distribution of code 
cards can be adequately controlled and 
counterfeiting eliminated, it is apparent 
that this also constitutes a closed system, 
in the sense that a secure communication 
channel between the encoding center 
and each subscriber's decoder is pro- 
vided, this time by the physical trans- 
port of a code card from the encoding 
center to the point of sale and from the 
point of sale to the subscriber's decoding 
unit. 

In contrast with the closed systems just 
described is the class of system which does 
not require a secure channel for the trans- 
mission to each subscriber's decoding 
unit of the decoding information appro- 
priate to the coded transmission being 
broadcast. In an "open system," as we 
shall call the latter type, the information 
necessary to decode the transmission is 
broadcast with the program. The fact 
that the transformation necessary to in- 
terpret this broadcast decoding informa- 
tion may be altered occasionally does not 
affect the fundamental difference be- 
tween a closed and an open system: in 
the closed system, part of the decoding 
information is transmitted in a private 
channel; while in the open system, the 
decoding information is broadcast with 
the program. 

The secrecy obtained in an open sys- 
tem clearly resides in the provision of a 



variety of possible codes which is suffi- 
ciently rich so that random experimenta- 
tion with a decoding mechanism identical 
with that provided to authorized sub- 
scribers will still be unlikely to produce 
an adjustment which corresponds to 
satisfactory decoding. That is, the open 
system must rely upon cryptographic 
security; the closed system, having a 
private channel, can transmit its decod- 
ing messages "in the clear." 

As is usual in cryptography, the 
method of encoding and decoding must 
not be allowed to remain unchanged for 
any considerable length of time, since 
this would provide opportunity for 
analysis of the code used. A complex se- 
quence of encoding and decoding meth- 
ods should be used ; one of the functions 
of the decoder can be to provide for the 
programming of the appropriate se- 
quence. At longer periods, the nature of 
the programming can be changed by al- 
tering settings in the decoder. To con- 
tinue the analogy with cryptographic 
communication, we see that this corre- 
sponds to a change in the "key" informa- 
tion used to encode and decode mes- 
sages, and requires a secure means of dis- 
tributing the key information. 

Given adequate cryptographic secur- 
ity, there is little doubt that an open sys- 
tem is preferable to a closed one. It does 
not involve the vast code-card prepara- 
tion and distribution problem charac- 
teristic of the Subscriber- Vision system, 
nor does it require of the subscriber that 
he make an expedition to the store in 
order to be able to see a show. It avoids 
adding to the already serious problems of 
subscription television the further prob- 
lems inherent in the use of a complicated 
and expensive wire communications sys- 
tem, as entailed in the original Phonevi- 
sion proposal. 

Accepting this conclusion, let us now 
discuss some of the ways in which an 
open system can be realized. We must 
first settle on the operating characteristics 
of a satisfactory subscription television 
system. 



Ridenour and Brown: Subscription Television 



187 



Operating Requirements 
for Subscription Television 

The choice of the most desirable oper- 
ating characteristics for a system of sub- 
scription television can be debated, and 
has been. No attempt will be made here 
to justify the choices which are charac- 
teristic of the Telemeter system, beyond 
remarking that they are based primarily 
on two main considerations : (a) conveni- 
ence to the user of the system, and (b) 
maintaining as close as possible an anal- 
ogy with practices which are standard 
and successful in existing forms of enter- 
tainment merchandising. Surely there 
can be no quarrel with the first considera- 
tion; the second has been adopted be- 
cause of our belief that practices em- 
pirically arrived at through centuries of 
experimentation are likely to be sound. 
On these bases, then, we believe that the 
ideal subscription television system will 
have the following properties: 

(1) It must operate for cash. With minor 
and trivial exception, entertainment 
has never been successfully sold on 
credit. There is no reason to suppose 
that the introduction of television as a 
medium for merchandising entertain- 
ment will change things radically enough 
to overturn the empirically justified view 
that it cannot be. It is our belief that the 
only practical way in which cash opera- 
tion of a subscription television system 
can be achieved is through the medium 
of a coin-actuated mechanism. 

(2) Prices for individual programs must be 
capable of being varied. Since the produc- 
tion costs of different programs are dif- 
ferent, and the value to the viewer even 
of the same program may be different at 
different times (e.g., first-run, second-run 
and third-run motion pictures), a sub- 
scription system which operates on a 
fixed-price basis has surrendered much 
of its potential flexibility and usefulness. 

(3) Shows must be sold on a program basis, 
not on a time basis. A baseball game that 
goes twelve innings must still be shown 
in its entirety to a viewer who has paid 



admission ; a person who pays for a mo- 
tion picture being shown twice in an 
evening must be permitted to sit through 
two complete showings of the picture for 
one admission, if he so desires, just as he 
could in a theater. 

(4) The identity, price and current status 
of a subscription television program should be 
announced for the benefit of those tuning to the 
channel carrying it, at all times during the 
program. In the present Telemeter sys- 
tem, this is accomplished by means of an 
additional aural channel called the 
"barker," which is received when a sub- 
scriber tunes to a channel carrying a pay 
show. If the subscriber elects to purchase 
the show, the barker is replaced by the 
program sound as soon as the price of the 
show has been met. In the absence of 
some such provision, dependence must 
be placed on other means of informing 
subscribers as to the shows being of- 
fered. While much can be done through 
newspaper advertising, special weekly or 
monthly program circulars, spot an- 
nouncements on radio and television, 
etc., we are of the opinion that the 
barker is a very important feature of a 
proper subscription television system. 

(5) An accurate record must be kept of 
every show purchased by every subscriber. 
While the primary requirement for mak- 
ing such a record lies in the fact that the 
producer of entertainment is accustomed 
to being paid on the basis of a. percentage 
of the gross admissions, there are ancil- 
lary reasons which make it desirable to 
keep a complete and detailed record, as 
we shall see. 

We now consider the alternative 
logical organization of systems that meet 
these requirements. 

Logical Organization 
of Subscription Systems 

The elements of the most general 
subscription television system meeting 
the requirements specified in the last 
section are shown in Fig. 4, together with 
the information-flow among the various 
units. The transmitter must be con- 



188 



August 1953 Journal of the SMPTE Vol.61 



Visuol display of program price, 




| Evidence 


of payment 


SUBSCRIBER 


BOX-OFFICE 

, UNIT 


RECORDER 


Aural indication of program price and identity 


Price of 
progrom 


Identity of 
program 




Brightness Info j 1 








ENCODER 
H AND 
TRANSMITTER 


sync, signals 


VER -* 


DISPLAY 


Program price and Identity 




Encoding 
signals 


/ 


JKey signals 




CODE 
GENERATOR 


J DECODER 








\ """SI* T 


* EVIDENCE OF PAYMENT 




SIGNALS IMPLICIT IN \ SUBSCRIBER- 
MENTIONS DEFINING CODE IDENTITY 
UNIT 








OCCASIONAL SETTINGS BY 



Fig. 4. Elements of the general coin-operated system. 



trolled by a code generator which both 
governs the convention used in encoding 
and also supplies for transmission key 
signals that relate to the encoding method 
in use. The price and identity of the pro- 
gram must also be transmitted, usually 
in two ways. The "barker" gives to the 
subscriber an aural indication of price 
and program identity; at the same time, 
a suitably coded version of the program 
price must be transmitted to what we 
have called the "boxoffice unit." It is 
the function of this unit to display the 
program price, to receive the coins de- 
posited in it by a subscriber who wishes 
to purchase the program, and, upon re- 
ceipt of the full program price, to present 
evidence of payment to the decoder, 
which thereupon commences to decode 
the program, and to the recorder, which 
thereupon makes a record of the identity 
of the program purchased. Coded pro- 
gram-identity signals must also be trans- 
mitted, in order to enable the recorder to 
work. 

It will be apparent that the decoder 
receives information from several sources. 
We have already noted that it is put into 
action by an evidence-of-payment signal 



from the boxoffice unit ; this signal may 
or may not play a part in the actual de- 
coding process, as we shall see presently. 
In addition, the decoder receives the key 
signals which the transmitter is sending 
to accompany the program, it has im- 
plicit in its construction some set of con- 
ventions defining a class of possible en- 
coding methods, and it may receive from 
what is called the "subscriber-identity 
unit" further key signals that play a role 
in the decoding process. The function of 
the subscriber-identity unit will become 
evident as the discussion proceeds. 

The fundamental organization of any 
subscription television system meeting 
the requirements we have laid down is 
that shown in Fig. 4. Detailed variation 
in the system design arises depending on 
the manner in which the four units of the 
subscriber's attachment boxoffice unit, 
recorder, decoder and subscriber-iden- 
tity unit are associated with one an- 
other. 

For example, consider Fig. 5. Here, 
by calling upon the subscriber himself to 
assist in the transport of decoding infor- 
mation, we have reduced to a minimum 
the amount of apparatus which must be 



Ridenour and Brown: Subscription Television 



189 



OUTPUT CODE 
INPUT CODE 



OUTPUT- CODE 
VENDOR 



PRICE, PROGRAM IDENTITY, 
AND INPUT CODE FROM 
ANOTHER SOURCE. EG 

NEWSPAPER , 



CONVENTIONS DEFINING CODE 



DECODING 
ATTACHMENT 



OCCASIONAL SETTINGS BY 
COIN COLLECTOR 




INPUT CODE PROGRAM 
PRICE AND IDENTITY 



BRIGHTNESS INFO 
AND SYNC. SIGNALS 



Fig. 5. Coin-operated system with subscriber intervention; remote vendor. 



electrically connected to the subscriber's 
receiver. The boxoffice unit and the re- 
corder have been associated in a device 
called a "vendor," which can be phys- 
ically isolated from the "decoding at- 
tachment" ; indeed, a single vendor can, 
if desired, serve a number of subscribers. 
Only the decoder itself and the sub- 
scriber-identity unit are associated in the 
individual decoding attachment. 

The system shown in Fig. 5 operates as 
follows: The subscriber is informed 
(e.g., by the barker) of the nature and 
price of the program available on the 
channel to which he is tuned, and he is 
given in addition a code message which 
characterizes the program. This code 
message must contain an indication of the 
price and identity of the program, in 
order for the vendor to work satisfac- 
torily. The subscriber then goes to the 
vendor and enters the code group char- 
acterizing the program, and another code 
group which serves to identify the sub- 
scriber himself. On the basis of these 
items of information, which together 
comprise the "input code" of Fig. 5, the 
vendor prepares itself to receive payment 
for the program. Upon the subscriber's 



meeting the price asked for the program, 
the vendor makes a recording of the 
identity of the program purchased and 
the subscriber's identity; it then presents 
to the subscriber a new code group (the 
"output code") which may simply be a 
message or alternatively may take some 
physical form, such as that of a code 
card. 

The subscriber now returns to his set 
and enters the output code into its de- 
coding attachment. On the basis of this 
information and that supplied it by the 
subscriber-identity unit, the decoder is 
actuated and the program is decoded. 
We now see one reason for the subscriber- 
identity unit. Without it, the full code 
required by the decoder would be avail- 
able to the subscriber, and this code 
would be the same for all subscribers. 
Collusion among subscribers would then 
enable a single output code purchased by 
one subscriber to be used by the entire 
group, without any record being made of 
this fact, since the recorder is located in 
the vendor. It is therefore necessary to 
render each output code unique to each 
subscriber, which can be done by causing 
the input code, and therefore the output 



190 



August 1953 Journal of the SMPTE Vol. 61 



VENDOR AND 

DECODER 

ATTACHMENT 



PROGRAM PRICE AND 
IDENTITY INFO FROM 
ANOTHER SOURCE; EG 
NEWSPAPER. i 




1 



BRIGHTNESS INFO 
AND SYNC. SIGNALS 



qCCASJpNAL_SETTINGS_BY__ 
~COrN~COLLECTOR~ 



Fig. 6. Coin-operated system with subscriber intervention; automatic input code. 



code, to be unique to each subscriber. 
The various individual output codes are 
then all translated back into the proper 
decoding pattern through the interven- 
tion of the subscriber-identity unit, whose 
settings have been chosen to match the 
variations in output code produced by 
the subscriber-identity part of the input 
code. 

The system of Fig. 5 represents the 
maximum degree of subscriber interven- 
tion in the decoding process which we 
think is at all feasible. Figure 6 shows a 
system which is more nearly automatic. 

In Fig. 6, the boxoffice unit and the 
recorder, which together comprise the re- 
mote vendor of Fig. 5, are associated with 
the decoder and the subscriber-identity 
unit in the subscriber's attachment, 
which must be physically and electrically 
joined to the television receiver. The in- 
formation on program price and identity 
reaches the attachment directly from the 
television receiver, without the inter- 
vention of the subscriber. The output 
code is presented to the subscriber, who 
enters it into the decoder. As in the 
system of Fig. 5, and for the same reasons, 
a subscriber-identity unit is necessary to 



handle output codes which are unique to 
each subscriber. The part of the input 
code which represents the subscriber's 
identity can be set into the recorder and 
boxoffice unit in a semipermanent 
fashion, since the entire attachment is and 
remains in the possession of a single sub- 
scriber. 

Another possible system is shown in 
Fig. 7. Here the subscriber intervenes to 
enter the input code, which has reached 
him via the receiver, perhaps through the 
agency of the barker. As in Fig. 6, the 
subscriber-identity part of the input code 
is built into the attachment and need not 
be entered each time the equipment is 
used. The output code now goes directly 
from the boxoffice unit to the decoder, 
entirely within the attachment. Under 
this arrangement, there is no longer any 
necessity for a complicated output code, 
nor for one unique to each subscriber. 
Since the output code is entirely unavail- 
able to the subscriber, it can consist 
simply of the closing of a relay which ac- 
tuates the decoder. An optional sub- 
scriber-identity unit is shown, for reasons 
which will become clear in a moment. 

Actually, when the attachment to a 



Ridenour and Brown: Subscription Television 



191 





VENDOR 
AND 
DECODER 
ATTACHMENT 








PAYMENT FOR PROGRAM 




BOX-OFFICE 
UNIT 




PROGRAM INPUT CODE SUBSCRIBER 


EVIDENCE 

OF 

PAYMENT 










IDENTITY OF 
PROGRAM 


PROGRAM INPUT Sftt ff^WL 
OR VISUAL DISPLAY 

INPUT CODE; 
PROGRAM PRICE 
AND IDENTITY 


RECORDER 










J 

1 

4ESS INFO 
SIC. SIGNALS 


DECODER 


PARTIAL KEY SIGNALS 1 




I RECEIVER 


CONVENTIONS 


DEFINING CODE 1 
PAR' 

r 

[ 


T 

MALI KEY SIGNALS 
1 
j 


1 
J 

sl< 

N 
C 


BRIGHT! 
AND SY 

)NAL 
3S BY 
OLLECTOR 


SUBSCRIBER- 
IDENTITY UNIT 
(OPTIONAL) 




* 




SETT 
1 COIN 

1 
1 



Fig. 7. Coin-operated unit with subscriber intervention; automatic output code. 



subscriber's set includes the boxoffice unit 
and the recorder, as well as the decoder, 
both the input code and the output code 
may as well be made automatic. This 
produces some simplification in the 
equipment and also represents a system 
which makes the minimum demands 
upon its user. The resulting fully auto- 
matic coin-operated system is the one 
used by Telemeter. Its logical organiza- 
tion is shown in Fig. 8. 

Price and program-identity informa- 
tion reach the Telemeter attachment 
directly from the television receiver; 
the price of the program is displayed 
visually to the subscriber by the box- 
office unit. Payment of the program 
price by the subscriber actuates the re- 
corder and the decoder. An optional 
subscriber-identity unit is shown in con- 
nection with this system, as it was in con- 
nection with that of Fig. 7. 

While the subscriber-identity unit is 
not needed in either of the last-men- 
tioned systems to guard the integrity of 
the output code, since this code never ap- 



pears outside the closed box housing the 
attachment, such a provision may be use- 
ful for the following reason. In any coin- 
operated system, a collector must periodi- 
cally call to collect the coins that have 
been deposited in each home unit. The 
collector will occasionally find no one 
home when he calls, and will thus be un- 
able to make a collection. One such 
failure to collect is tolerable, but two or 
more such failures lead to the danger that 
the coinbox will be overfull, or the re- 
cording medium used up, or both, be- 
fore a successful collection is made. We 
may say parenthetically that this con- 
stitutes something of an argument in 
favor of the remote vendor, which can be 
placed where a collector can always have 
access to it. Nevertheless, the subscriber 
convenience afforded by the system of 
Fig. 8 seems to us sufficient to overwhelm 
this apparent advantage of the system 
shown in Fig. 5. 

The difficulty just mentioned can be 
ameliorated by the use of a subscriber- 
identity unit, not to identify any par- 



192 



August 1953 Journal of the SMPTE Vol. 61 



IDENTITY UNIT I 
(OPTIONAL) 




AURAL INDICATION 
OF PROGRAM PRICE 
AND IDENTITY 



PROGRAM PRICE 
AND IDENTITY; 
PARTIAL KEY 
SIGNALS 



BRIGHTNESS INFO. 
AND SYNC. SIGNALS 



L j 

CONVENTIONS DEFINING CODE ' 

Fig. 8. Telemeter: a fully automatic coin-operated system 



ticular subscriber, but rather to indicate 
that a sufficiently recent call by a col- 
lector has been made. That is, the sub- 
scriber-identity unit used in this fashion 
may be provided with a code sufficiently 
redundant so that its June setting by the 
collector will operate satisfactorily during 
June and July, but not August ; the July 
setting will operate for July and August, 
but not September, and so on. This will 
permit one unsuccessful call by the coin 
collector, but no more than one; if a 
second unsuccessful call is made, soon 
thereafter the Telemeter attachment will 
no longer operate satisfactorily. Occa- 
sional settings of the subscriber-identity 
unit by the coin collector have been in- 
dicated in Figs. 4-8 inclusive, to provide 
for this use of the unit. 

Realization of the Telemeter System 

It will be apparent from the foregoing 
discussion that many alternative ways are 
available for realizing a system of the logi- 
cal organization and operating features 
preferred by the International Telem- 



eter Corp. A vigorous program of de- 
velopment is being carried out to deter- 
mine the optimum detailed design for the 
system; since this is still in progress, it 
would be premature to discuss here the 
details of the encoding, decoding and 
other means used in the Telemeter sys- 
tem. The authors feel strongly that, as is 
usual in engineering development, a de- 
cision on what had best be done is far 
more important than the details of how 
it is to be accomplished; the present 
paper is therefore devoted to establishing 
a rational basis for the design of a satis- 
factory pay-as-you-see television system. 

Discussion 

Wm. H. 0/enhauser, Jr. (Andre DeBrie of 
America, Inc.}: I see that the author has 
used an entirely new set of terms with 
which this Society is totally unfamiliar. 
For instance, the terms encode, decode, and 
secure channel are basic terms that have 
not appeared previously in our proceedings. 
Will the author be good enough to add an 
explicit glossary and bibliography at the 
end of his paper that will enable readers of 



Ridenour and Brown: Subscription Television 



193 



our Journal to appreciate these new con- 
cepts and terms? 

Mr. Ridenour: I'll do my best. "Secure" 
is a word that the Navy uses in a different 
sense from everybody else. As a matter of 
fact, the Navy uses it in two senses. One 
means "to sweep out" and the other means 
"to keep private"; it's the "to keep pri- 
vate" use of the word that I had in mind. 
"Encoding and decoding" is just a more 
precise way of talking about what is often 
called "scrambling and unscrambling." 
The latter terms are inappropriate, be- 
cause, in order to get a picture through a 
needle's eye the way you must in television, 
you have to encode the picture in the first 
place and decode it at the receiver. Thus, 
all that is meant by "scrambling" is that 
you use a nonstandard method of coding 
and decoding. Note also that "non- 
standard" is a term which has only a geo- 
graphical reference; the transmission code 
that we regard as standard would be quite 
unintelligible to a French receiver. It is 
important to the understanding of the 
subject not to use the terms "scrambling 
and unscrambling" but to use "coding and 
decoding" instead. 

Axel Jensen (Bell Telephone Laboratories, 
Murray Hi//, N.J.): It is quite true that we 
are in a new field. New ideas are coming 
out all the time; and when the engineers 
have new ideas they put words to them 
you can't help that. It's up to Societies 



like SMPTE and IRE later to take a hold 
of those things and try to standardize some 
of the terms that are being used. I don't 
think we should worry too much about it 
in the very early stages. Eventually those 
things will get themselves straight. 

Anon: I would like to know who owns and 
maintains the auxiliary equipment for the 
receiver. 

Mr. Ridenour: I'm talking out of turn to 
answer that question, because this is a 
matter of policy that will have to be de- 
cided after a considerable amount of 
thought. However, it seems likely that the 
attachments to people's receivers will have 
to be managed on the same basis as are 
telephone instruments. That is, they will 
have to be, and remain, the property of the 
operating company, for several reasons. 
One is that you have to be able to fix them ; 
another is that you must have access to 
them in order to collect money if it's a 
coin-operated mechanism, and so on. 

Anon: Then in view of that would you 
say that it is actually cheaper than a tele- 
phone line? 

Mr. Ridenour: I have asked some tele- 
phone engineers about the capital cost 
represented by a single home telephone 
installation; it runs well over $350 in the 
operating company of which I inquired. 
Now I'm quite sure we can build a satis- 
factory pay-as-you-see unit for considerably 
less than that. 



194 



August 1953 Journal of the SMPTE Vol. 61 



Closed-Circuit Video Recording 
for a Fine Music Program 



By W. A. PALMER 



The requirement that an experimental series of ' 'Standard Hour" television 
concerts be released in six markets on 16mm film posed special problems of 
economics and quality. Closed-circuit special video recording was used in- 
corporating a number of unconventional techniques such as the use of direct- 
positive "reversal" masters and negative-image release prints. Prescoring 
was used for all musical numbers and audio procedure made use of J -in. 
magnetic tape, 16mm magnetic film, and a direct-positive electro-printed 
variable-density sound track for final release. 



HEN the Standard Oil Company of 
California decided to make an experi- 
mental television version of "The Stand- 
ard Hour" musical programs, there were 
several requirements immediately appar- 
ent. 

(1) The program would have to be 
released in six western markets from 
16mm film since a network hook-up for 
these stations was not available. 

(2) Audio quality from the 16mm film 
would have to meet AM radio-network 
standards so that the radio audience, 
built up over a period of twenty-five 
years, would not feel a loss in musical 
value as a result of the addition of the 
visuals. 

(3) Each program would include a 



Presented on April 28, 1953, at the Society's 
Convention at Los Angeles by W. A. 
Palmer, W. A. Palmer Films, Inc., 611 
Howard St., San Francisco 5, Calif. 
(This paper was received March 27, 1953.) 



symphony orchestra, a "star" vocalist, a 
new young "discovery," an instrumental 
soloist and a ballet number. 

(4) Technical procedures followed 
would have to be efficient and flexible 
enough to produce the required film 
material within moderate budget limits. 

(5) The caliber of the musical per- 
formance and the "stage-craft" used on 
settings would have to be of the highest 
order. 

After a number of tests and the making 
of a pilot film, it was decided to use 
closed-circuit video recording in con- 
junction with prerecording of the music. 
In other words, there was to be a com- 
bination of television and motion-picture 
techniques to take advantage of the 
efficiency of the electronic cameras and 
still have the advantage of the more flexi- 
ble handling of musical numbers which 
has been common in the theatrical 
motion-picture industry for many years. 



August 1953 Journal of the SMPTE Vol. SI 



195 




Fig. 1. General working area; television cameras indicated by arrows. 



Or expressed in terminology which has 
been suggested before: "Electronic 
Motion Pictures" were to be used. 

The programs were produced in 
"units," each unit supplying several 
musical numbers which could be spotted 
on several programs throughout the 
series. In this way it was possible to have 
several appearances of a given artist and 
achieve a great variety in each program. 
A "unit" involved four days shooting 
during which enough material for one 
and a half programs was obtained. 

Audio 

The production of "The Standard 
Hour" television programs started with 
the recording of the musical sound tracks 
on Ampex j-in. tape recorders at the 
ABC San Francisco studios. The J-in. 
tape is, of course, not a synchronous 



medium, but since "prescoring" was to 
be used, an absolutely synchronous 
method was not necessary at this stage 
and the unperforated tape made possible 
more precise editing. 

Two Altec 21 B microphones were used, 
one general pickup for the orchestra and 
one for the soloists. 

In preparing the music, a great deal of 
advantage was taken of the facility of tape 
editing, permitting the combination of 
several takes to get a more nearly perfect 
performance. With nonperforated mag- 
netic tape, the assembly of parts of a 
musical number could be accomplished 
with great precision, since a splice could 
be made at any desired point, such as 
between sixteenth notes, without evi- 
dence that a cut and splice had been 
made. 

With the completion of the editing of 



196 



August 1953 Journal of the SMPTE Vol. 61 



the tapes, the music was re-recorded to 
magnetic 16mm perforated film running 
at 72 fpm. This became the master 
sound track for all subsequent operations. 

At the same time, an additional trans- 
fer of the music was made to a 16mm 
direct-positive photographic sound track 
while a voice called out numbers at 
intervals to identify various musical 
phrases. The photographic track, re- 
corded at the standard 16mm speed of 
36 fpm, was used to play back and cue 
the artists during photography. 

Disks were also made and given to the 
artists so they could rehearse with the 
recording in privacy prior to the shooting 
sessions. 

Equipment for Photography 

During the photography sessions at the 
Civic Auditorium at Richmond, Calif., 
four standard RCA image-orthicon 
camera chains were used as in a regular 
KGO-ABC "remote" job. 

Figure 1 shows the general working 
area with television cameras (indicated 
by arrows) on the set in the background 
and the control and recording equipment 
in the foreground. 

A Houston-Fearless "Academy" crane 
was used for most shots where a mobile 
camera was needed. A second camera 
was mounted on a Fearless baby boom 
or perambulator and a third was 
mounted on a RCA pedestal. The 
fourth camera was mounted on a field 
tripod, usually located on a high parallel 
to cover "pattern" shots on ballet se- 
quences. 

The usual lens complements were 
available for all cameras with the addi- 
tion of a Walker Electro-zoom lens. 

All four cameras, with their associated 
field monitors, were fed through a field- 
switching unit to a TM5A monitor which 
had a video-recording camera focused on 
it. 

The 16mm video-recording camera 
used is of special design with a shutter- 
optical system combination permitting 
a shutter-bar free picture to be obtained 



from the regular 10-in. P4 long-persist- 
ence phosphor kinescope. 

An optical system in the camera shows 
an enlarged upright image of the film 
aperture. Line-up, focus and "picture 
splice" phasing is done by visual inspec- 
tion through this optical system and the 
image on the film may be watched during 
actual photography. 

Picture quality on the monitor was 
judged by eye with the aid of a Norwood- 
Bolex exposure meter to set the average 
light level. The hemisphere light shield 
was not used on the Norwood meter but 
the bare cell was held close to the tube 
face to make a reading. 

Lighting equipment was conventional, 
mostly 2-kw juniors and 750-w "babies," 
with a few 5-kw seniors and sky pans. 
The great sensitivity of the image orthi- 
cons permitted a light level considerably 
lower than required for regular motion- 
picture photography even though lenses 
were usually used at about //5. 6. 

Photographic Procedure 

In photographing the various musical 
numbers, the photographic sound track 
with its voiced cue numbers was played 
back through horns on the set while the 
artists sang or played along with the 
track. As an added help in synchroniz- 
ing, "clicks" were placed in the track 
wherever there was a drastic change in 
tempo or a rubato. Audio playback 
equipment is shown at the extreme right 
of Fig. 2. 

Sometimes, whole musical numbers 
or at least half of a number would be 
photographed in one "take," individual 
scenes being switched or electronically 
"cut" from the several cameras. At 
other times one camera position at a time 
was used and the "cutting" or editing 
left for the finishing operations in making 
up the final shows as is the usual tech- 
nique in regular film making. 

As the recording or photographic proc- 
ess was going on, the artists performing in 
synchrony with their played-back music, 
the sound track was also being re- 



Palmer: Video Recording of Music 



197 




Fig. 2. Arrangement of monitors and controls; audio playback equipment 

at extreme right. 



recorded on a "single system" modulator 
within the 1 6mm video-recording camera 
on the same film that recorded the pic- 
ture. This track was used as a guide for 
matching the master sound track in the 
later operations and served as a sound 
source during the showing of "rushes" 
and in the "rough cut" stages of making 
up complete programs. 

Du Pont Type 930 or Eastman Plus X 
film was used and processed by the re- 
versal method to give a direct-positive 
master. The commentator and the pro- 
gram pages were also photographed on 
16mm reversal film by conventional 
motion-picture methods. 

Make-up of Complete Programs 

Since the final release would have to be 
on 16mm film run on conventional 
iconoscope chains, experiments were 



made with different qualities of both 
positive and negative prints off the 1 6mm 
masters with a view to obtaining the best 
transfer characteristics or gray-scale 
rendering. The negatives were run on 
the television film chain with polarity 
reversal to yield a positive image. These 
test prints were also put out over the air 
as an engineering test and observed on 
home receivers. The most satisfactory 
transmission resulted from the use of the 
negative images since the well-known 
highlight compression characteristics 
of the iconoscope became compression 
of the shadows which was actually bene- 
ficial to gray-scale rendering. By virtue 
of the 16mm master reversal film, the 
negative television release prints could be 
contact-printed directly without incur- 
ring losses in successive steps. The 1 6mm 
reversal original thus became the master 



198 



August 1953 Journal of the SMPTE Vol. 61 



from which all air release prints were 
made. 

The original reversal film had a sound 
track recorded alongside the picture as 
described above and from this composite 
original, a work print was made by the 
reversal method to be used for editing. 
This was accomplished more easily than 
would have been the case if the usual 
"double film" technique were used. 
The usual objections to editing a com- 
posite sound-and-picture film did not 
apply here because the various scenes 
that were to be joined had an overlap of 
common sound track of identical modu- 
lation. It was therefore only necessary 
to find the duplicate modulations on two 
scenes to find the accurate cutting point 
by reference to either picture or sound 
track. The fact that the cutting point 
was 26 frames behind the sound modula- 
tion created a minor hazard that had to 
be kept in mind to avoid errors. 

When the final assembly of the entire 
program was made, combining the vari- 
ous ingredients, stock opening and clos- 
ing, audience reaction, commentator 
"on camera," program pages, and insti- 
tutional message, it was necessary to go 
to separate films for sound track and 
picture. However, a shortcut was used 
to avoid having to run many of the pre- 
views in interlock with three sound 
tracks. 

The voice track for the commentator 
was recorded on 16mm magnetic film at 
36 fpm and this was assembled on the 
same reel interspersed with the photo- 
graphic-cue track which was used for 
playback during photographic sessions. 

Interlock projections of the entire pro- 
gram could then be made with just one 
sound track, the combination magnetic- 
voice and photographic-music track 
running in synchronism with the picture 
work print. A special reproducer for this 
combination sound track was devised so 
that both magnetic and photographic 
sound could be reproduced as each type 
alternately passed the reproducing point. 



This combined photomagnetic reel 
also served as a guide to set up the master 
music tracks which were double length, 
that is 72 fpm for maximum fidelity, 
having a frequency range of 20 to 1 5,000 
cycles. The matching between the com- 
bination photomagnetic track and the 
72-fpm magnetic track required a 
synchronizer with a two-to-one gear ratio 
between sprockets. 

Making Final Release Prints 

The master 16mm reversal positives 
were set up in A and B reels for the entire 
length of the programs since there were 
many effects, particularly lap-dissolves, 
in each program. Wherever possible in 
the musical numbers, each master scene 
was left in its full length so that the place- 
ment of the dissolve could be changed if 
desired for improved effect after the first 
answer print or for a different editing in 
future use of the same material. 

Eastman Type 7365 Fine Grain Dupli- 
cating Positive was selected for the nega- 
tive-image release prints which were con- 
tact printed from the master positive A 
and B rolls. The stock had been first pre- 
fogged on the picture area only, to a den- 
sity of 0.2. This served to flatten out the 
toe of the emulsion characteristic and still 
further improve shadow detail in the final 
television transmission. 

The picture was printed to have a 
density range in the negative image 
from a maximum of 1.5, representing the 
highest highlight, to 0.2 for the deepest 
shadow. The film was developed in a 
D76 negative developer to a gamma of 
1.0. 

Electrical Printing of Sound Tracks 

The sound track was re-recorded or 
electro-printed to each release print from 
three sound channels running in syn- 
chrony. One channel had the commenta- 
tor's voice on magnetic 16mm film (the 
magnetic part of the combination photo- 
magnetic film used in editing). A second 
channel had all the musical numbers and 
was the 72-fpm 16mm magnetic film. 



Palmer: Video Recording of Music 



199 



The third channel was used for applause 
tracks. 

Each applause track was an authentic 
complete recording taken from one of 
"The Standard Hour" radio broadcasts 
and started with the normal scattered 
claps, building up to the full volume and 
gradually subsiding. 

The Type 7365 emulsion with its ex- 
tremely fine grain and yellow dye is most 
suitable for a high-quality printed sound 
track but posed some problems in regard 
to an electrically printed transfer be- 
cause of the extremely low sensitivity, the 
emulsion speed being approximately one- 
ninth the speed of Eastman Type 7302 
stock. 

Since a satisfactory balance density for 
a variable-area direct-positive track is 
very low 1 when applied to medium- 
contrast positive emulsions, it seemed 
desirable to use a variable-density track. 

The sound track was transferred to the 
7365 emulsion by a Western Electric 
RA1231-G recorder equipped with a 
special modulator. This was an adap- 
tion of the RA294 mirror-type modu- 
lator 2 - 3 with revised optical system de- 
signed to give a variable-intensity modu- 
lation and compensate for the emulsion 
characteristic of the 7365 stock yielding 
a linear-density record in the range be- 
tween a density of 1.0 and the clear film 
base. The unusually large mirror of the 
modulator (6.7 X 10.0 mm) made pos- 
sible adequate exposure of the film with- 
out overvolting the exposure lamp. Nine 
decibels of noise reduction was used since 
the optical compensation for the emul- 
sion characteristic extended through the 
"toe" to well into the "straight-line" 
portion. This gave a sound track with a 
frequency response from 30 to 6000 cycles 
and with a signal-to-noise ratio of about 
40 db, meeting the standards of AM net- 
work broadcasting. 

Conclusion 

The method of closed-circuit video re- 
cording described makes possible a very 
efficient means of good quality television 



transcription with all the flexibility of 
live-television camera technique com- 
bined with the editing and selection ad- 
vantages of motion-picture production. 

The use of prescoring for a musical 
program was shown to be entirely practi- 
cal and eliminated all problems of micro- 
phone placement as well as insuring flaw- 
less musical performance. 

The enthusiasm of the artists for the 
method was noteworthy. Most volun- 
teered their preference for this combina- 
tion of television and motion pictures 
wherein the intense pressure of live-tele- 
vision production and the boredom of 
painstaking motion-picture production 
are each tempered to a happy medium. 

References 

1. John G. Frayne, "Electrical Printing," 
Jour. SMPTE, 55: 590-604, Dec. 1950. 

2. R. W. Benfer and G. T. Lorance, "A 
200-mil variable-area modulator," Jour. 
SMPE, 36: 331-340, Apr. 1941. 

3. W. R. Goehner, ''A new mirror light- 
modulator," Jour. SMPE, 36: 488-496, 
May 1941. 

Discussion 

Ralph Lovell (NBC, Hollywood, Calif.): 
Bill, you were very modest about the 
camera. I think you just mentioned that 
it was specially constructed. Would you 
be kind enough to tell us a bit more about 
how you designed it and from what source 
you started building this camera? 

Mr. Palmer: The camera is still under 
some development. It might properly 
be a subject for a future paper. The 
basic mechanism makes use of parts from 
a Bell & Howell projector shuttle with a 
shutter optical system which permits a 
fade-out fade-in type of action resulting 
in a "picture splice" which occupies about 
30 television lines instead of the usual 
three or four. To describe it more fully, 
of course, would require some detail which 
time does not permit. The unusual feature 
is that it makes possible the use of a long- 
persistence white phosphor kinescope. 
The shutter action can be compensated 
for any given emulsion to give a shutter-bar 
free recording. 



200 



August 1953 Journal of the SMPTE Vol. 61 



Air. Lovell: You said a Bell & Howell 
movement. Does that indicate a Bell & 
Howell projector movement? 

Mr. Palmer: Projector movement, yes. 

Mr. Lovell: Did you also do the same 
thing with the 35mm movement, make a 
35mm camera? 

Mr. Palmer: I made a 35mm camera 
which was used only on the later recordings 
and because we did not have complete 
material in 35mm we used it as a protective. 
It has an accelerated Geneva projector 
movement with a shutter mechanism 
similar in principle to the 16mm camera. 

Mr. Lovell: I think we all admire you 
for your ingenuity in making a camera 
out of a projector. I'd like to ask you, in 
view of your experience, if you were to 
initiate another series, what changes 
would you make? I'm particularly in- 
terested would you continue with the 
P4 phosphor, or would you try to use the 
Pll as many other people do? 

Mr. Palmer: We would, of course, like 
to have a high-definition system, since 
we don't have to be compatible with 
the 525-line system on a closed circuit. 
We would probably prefer to continue 
the use of the P4 phosphor because it 
allows us to judge the picture quality by 
eye, a very important factor. In this 
experimental series we could tell directly 
from the gray scale apparent on the 
monitor, the type of recording we would 
get. The emulsions and the processing 



chosen were such that we had approxi- 
mately a unity gamma system through to 
the home receiver. Actually we did gain 
a little contrast, but our visual impression 
on the P4 phosphor gave us a good indica- 
tion of the final result in the home. Our 
tests did not indicate that, within the 
limitations of the 525-line system, we would 
gain appreciable definition from a Pll 
tube. 

Benjamin Berg (Benjamin Berg Agency, 
Los Angeles): What is the pulldown time 
on your shuttle? 

Mr. Palmer: The camera shuttle 
operates with approximately a 30 degree 
pulldown. Seventy-two degrees are avail- 
able for shutter action and pulldown so we 
had a little leeway of some 40 degrees to 
spread the picture splice. 

Anon: I'd like to know how you accom- 
plish this splice of the picture. Is this a 
conventional shutter or does the density 
of the shutter itself vary? 

Mr. Palmer: It's a little hard to describe 
in a brief answer, but the shutter is a rotary 
type with two moving parts which co- 
operate with and are a part of the optical 
system. The shutter creates an intensity 
variation at the film, so that there's no 
area modulation of the image at the film 
aperture and the rate at which the shutter 
opens and closes is variable by adjustments 
that can be made, similar to the use of 
shaped masks for direct variable-density 
recording with a mirror-type modulator. 



Palmer: Video Recording of Music 



201 



Engineering Activities 



Stereophonic Sound 

A major revolution is quietly taking 
place in the sound end of the motion- 
picture industry. Stereophonic sound has 
made its "debut," has been well accepted 
and is apparently here to stay, but its 
entry has been somewhat obscured by the 
simultaneous and very dramatic intro- 
duction of 3-D and wide screens. 

All that glitters is not gold and all 
multiple-track sound recording is not 
stereophonic, although often highly touted 
as such. True stereo (auditory perspective 
of lateral location and depth) requires the 
use not only of multiple recording channels 
but properly spaced microphones as well. 
Pseudo-stereo may employ one mike in 
the studio whose output is later re-recorded 
on one or more of the multiple tracks to 
simulate a stereophonic effect. The result- 
ing sound illusion on the screen may, 
however, if astutely done, bear a marked 
resemblance to the original sound scene 
and if it is, the audience will probably feel 
a sense of sound perspective. 

Magnetic recording (the stereo sound 
medium) was first used in motion picture 
studios in 1 947 and was confined to original 
recording from which a photographic 
track was re-recorded for release. The 
rapid adoption of the magnetic medium 
led early to a need for industry standards. 
The Society's Sound Committee took the 
initiative here and after much discussion 
and some delay a 35mm, 3-track, magnetic 
proposal was approved as an American 
Standard (PH22.86-1953 in the May 
1953 Journal}. 

The development of this standard 
greatly furthered the use of stereo sound 
in the theater, for it provided a ready 
vehicle for both the studios and equipment 
manufacturers to rapidly exploit this 
advance in sound realism. 

However, in one respect this may be 
characterized as "one step forward and 
two steps back" for, as they were in the 
first days of sound, picture and sound are 
again on separate media. The separate 



magnetic 3-track reproducers and selsyn 
sync control systems now used in stereo 
sound are certainly a far cry from the 
phonograph and disk record used in the 
twenties. Nonetheless, they are looked 
upon as an added complexity in the pro- 
jection booth, and at that, but a stopgap 
measure. Just how soon composite picture 
and stereo sound will be generally available 
is anyone's guess at this point, but it 
certainly looms as an early eventuality. 
The August 13, 1953, demonstration of 
CinemaScope's composite picture and 
stereo sound undoubtedly lends weight to 
the notion that the single-film system is, 
at any rate, technically feasible right now. 

This places the exhibitor in somewhat 
of a spot. Should he buy dual-film stereo 
sound equipment now or hold off until 
single-film features and equipment are 
available? 

It would appear that the exhibitor would 
have to consider three factors before 
making his decision: 

(1) the effect of 3-D sound on boxoffice 
receipts, 

(2) the number of dual-film features 
scheduled for production and release, 
i.e., pay-off time, 

(3) amount of first equipment which 
could be converted for use with final 
equipment. 

Estimates on the latter two factors are 
available. John Milliard, Chairman of the 
Sound Committee, conducted an informal 
survey of the Hollywood studios the first 
week of August which revealed that 
roughly 40 dual-film features are in 
production or in the planning stage. A 
recent conference of East Coast engineers 
and exhibitors estimated that about 75% 
of initial investment in stereo sound equip- 
ment (amplifiers, speakers, etc.) could be 
used directly in a later conversion to a 
single-film system. 

Status of the Theater-Screen Survey 

The survey initiated by the Theater 
Engineering Committee in May 1953 was 



202 



described in the preceding Journal. At 
this writing some eight thousand question- 
naires have been distributed with but 250 
returned. At least twice this number of 
returns are required before a statistical 
analysis can be made. Since this survey 
can be an important factor in standardizing 
a new aspect ratio, exhibitors are being 
urged to request, fill out and return these 
questionnaires. 

Standards 

The new is based on the old: despite 
its active participation in the new develop- 
ments, the Society is continuing unabated 
its usual standards activity. To this end, 
the Board of Governors, at its July meeting, 
approved 11 reaffirmations and two 
revisions of existing standards : 

Reaffirmations: PH22.27, -.37, -.46, 
-.47, -.60, -.62, -.65, -.66, -.67, -.69 
and -.70. 

Revisions: PH22.43 and -.44. 

These standards have since been sub- 
mitted to the Photographic Standards 
Board of the ASA and will in all likelihood 
be given formal ASA approval within the 
next two months. 

In addition the following projects are 
in the works: 



Film Projection Practice Committee: with- 
drawal or revision of American Standard 
PH22.28-1946, Projection Rooms and 
Lenses for Theater, SMPTE 628. 

76mm and 8mm Motion Pictures Committee: 
withdrawal of American Standard 
PH22.54, 16mm Travel Ghost Test Film, 
SMPTE 61 1 ; and revision of two American 
Standards PH22. 15, 16mm Film Per- 
forated One Edge Usage in Camera, 
SMPTE 518, 614; and PH22.16, 16mm 
Film Perforated One Edge Usage in 
Projector, SMPTE 519, 615. 

Sound Committee: four proposed American 
Standards SMPTE 617, 35mm 3-Track 
Magnetic Flutter Test Film; SMPTE 618, 
Azimuth Alignment Test Film for 35mm 
3-Track Film With Magnetic Coating; 
PH22.88, Dimensions for Magnetic Coat- 
ing on 8mm Motion Picture Film, SMPTE 
624; and SMPTE 626, Magnetic Coating 
on 16mm Film Perforated Two Edges. 
And revision of three American Stand- 
ards PH22.42, 16mm Sound Focusing 
Test Film, SMPTE 622; PH22.45, 16mm 
400 Cycle Signal Level Test Film, SMPTE 
623; and PH22.57, 16mm Buzz Track 
Test Film, SMPTE 621. 

Copies of any of the above proposals 
are available upon request. Henry Kogel, 
Staff Engineer. 



Southwest Subsection Meeting 



A successful meeting of the Subsection was 
held on May 20 at the Beard & Stone 
Electric Company auditorium in Dallas. 
The membership of the North Texas 
section of COMPO were invited to meet 
with us to hear Herbert Barnett's speech 
to the Western Pennsylvania exhibitors 
convention. However, COMPO had a 
benefit barbecue for the Waco tornado 
victims the same evening so we had only 
two guests. 

There were 18 people present including 
Hervey Gardenhire who has come about 
300 miles from O'Donnell, Texas, for 
every meeting we have had except the one 
of last November when the roads were 
too "iced-up" for travel; also there were 
members from San Antonio and Austin. 

Mr. Barnett's paper was read by pro- 



gram chairman I. L. Miller, and subsection 
chairman Bruce Howard read W. A. 
Palmer's Los Angeles convention paper, 
"Closed Circuit Video Recording for a 
Fine Music Program." 

There was some discussion on the type 
of meetings held thus far by the Subsection, 
and a committee composed of Hugh 
Jamieson, Sr., J. Oakleigh Hill and A. B. 
Chapman was appointed to draft a letter to 
the Southwest Subsection membership, ask- 
ing their preference as to program ma- 
terial, meeting places and choices of days 
of the week. It was hoped that informa- 
tion in response to this inquiry would be 
on hand in time to be of use in planning 
the first Fall meeting. Hugh Jamieson, Jr., 
Secretary-Treasurer, Southwest Subsec- 
tion, 3825 Bryan St., Dallas 4, Texas. 



203 



Central Section Meetings 



Following the May 21 meeting described 
in the June Journal, the Central Section 
soon held two more meetings on May 27 
and June 11, making an unprecedented 
total of three meetings taking place in as 
many weeks. The May 27 meeting, held 
at the Western Society of Engineers, 
Chicago, drew about 220 for an evening 
of stereoscopy. Those attending saw what 
was described as the first industrial 3-D 
film to be made Packaging the Third 
Dimension, by Academy Film Productions 
Inc., Chicago, dealing with the manufac- 
ture of corrugated cartons. Guests from 
the Northern Illinois College of Optometry 
were also on hand at this meeting to hear 
an interesting and provocative paper on 
"Beneficial Effects of Properly Produced, 
Projected and Viewed Stereoscopic Motion 
Pictures on Binocular Visual Performance," 
by R. A. Sherman, of Bausch & Lomb 
Optical Co., Rochester, N.Y. This paper 
had already attracted considerable atten- 
tion at the Los Angeles Convention, where 
it was first presented. It was plain from 



the success of this meeting that 3-D is a 
prime attention-getter, and it is likely 
that additional papers on this subject will 
be presented in the Fall. 

The meeting on June 11 was held at 
the Geo. W. Colburn Laboratory, Inc., 
Chicago. Mr. Colburn gave a report 
describing the progress that has been 
accomplished in applying the SMPTE 
proposed standard for printer light cuing 
of 16mm motion-picture films; and a 
paper by Edward Yuhl on the RYB 
"Wireless Mike," a lightweight trans- 
mitting microphone, was presented by 
Henry Ushijima. About 125 attended 
this meeting, which concluded with a 
tour of the Colburn Laboratory facilities, 
and refreshments. 

Tentative meeting dates for the Fall 
Season have been set for September 11, 
at Dayton, Ohio, and October 15, No- 
vember 12 and December 10, at Chicago. 
James L. Wassell, Secretary-Treasurer, 
Central Section, 247 E. Ontario St., 
Chicago 11. 



Pacific Coast Section Meetings 



Under the direction of Herbert Farmer, 
Faculty Advisor and Acting Head of the 
Department, and Kenneth Miura, Chair- 
man of the Student Section, SMPTE, the 
fifth meeting of the Pacific Coast Section 
of the SMPTE was held at the Department 
of Cinema, University of Southern Cali- 
fornia, on May 19, 1953. 

Society members and guests had dinner 
on the campus, followed by a presentation 
of short papers and demonstrations of 
motion-picture productions and special 
projects presently under way at the 
campus. 

The program opened with a recent short 
motion-picture production made by the 
Department of Cinema. Following this, 
Richard Polister spoke on "The Scope of 
Motion-Picture Production in Colleges 
and Universities," reviewing the technical 
progress of production units in various 
universities and colleges throughout the 



country. Nicholas Rose, Director of 
Research in the Department, then spoke 
on "Analysis of Audience Reactions and 
Behaviors." He described systematic 
techniques for studying audience behavior 
in the evaluation of film effectiveness, and 
explained their development in the Re- 
search Division of the Cinema Depart- 
ment. A film demonstration of the various 
processes used was shown. "Uses of 
Silhouette Special Effects" was the subject 
explored by William Mehring, Instructor 
in Cinema, and covered a new motion- 
picture technique which has become a 
worthwhile classroom tool in the study of 
directional problems. A review of the 
production activities of the Department 
was given by Wilbur T. Blume, Director 
of Productions, with accompanying screen 
excerpts from recent films. The formal 
meeting was followed by an open house of 
the Department of Cinema. 



204 



For the June meeting, the last before 
the summer vacation, the Pacific Coast 
Section enjoyed an evening at NBC, 
Burbank, on June 23, 1953. NBC's new 
and modern plant is located on a 48-acre 
property which provides considerable space 
for future expansion. Two large audience 
studios are already completed, and there 
are two large rehearsal halls and a modern 
Production Services building containing 
several interesting innovations. Due to 
the broad interest of this program, members 
were invited to bring guests, resulting in 
the second largest meeting of the year, 
with 460 in attendance. 

A. H. Saxton, Technical Network 
Operations Manager, welcomed the group 
and exhibited a 35mm kinescope recording. 
"A New 35mm Single Film System Kine- 
scope Recording Camera" was described 



by Ralph E. Lovell, Kinescope Recording 
Supervisor. The first production model 
was shown, containing many interesting 
features. Marvyn S. Adams, Technical 
Operations Supervisor, spoke on "Tech- 
nical Operating Facilities of the Burbank 
Studios," describing many of the special 
interlocking, automatic and interconnecting 
features which have been provided to 
meet present needs and to provide maxi- 
mum flexibility for future requirements. 
A large screen theater TV unit for audience 
viewing was demonstrated. Special fea- 
tures of "Staging Services at the Burbank 
Studios" were described by R. Don 
Thompson, Manager of Television Staging 
Operations. 

A tour of the entire NBC installation in 
Burbank followed the formal program. 
Philip G. Caldwell, ABC Television Center, 
Hollywood 27, Calif. 



Photographic Technology and BS Degrees 



The Department of Photographic Tech- 
nology at the Rochester Institute of 
Technology has built up a considerable 
reputation since it was founded in 1930, 
and at the present time stands high among 
schools of this kind. Two-year courses, 
including Processes of Color Photography 
are available, leading to the Associate in 
Applied Science degree. The New York 
State Board of Regents has approved 
plans which the Institute expects to have 



in effect so that students entering this 
Fall can begin study toward a bachelorate 
degree. Of about 100 students graduated 
yearly, several begin a career in some 
phase of motion-picture work. So far 
there have been no specific courses in 
motion-picture photography available, but 
tentative plans are being made to in- 
corporate a major course in this field a 
year from now. 



Journals in Two Parts 



PART II of this Journal has the complete roster of the papers from the Screen Bright- 
ness Symposium held at the recent Los Angeles Convention. Reprint copies of this 
symposium are available from Society headquarters at $1.00 each. 

Next month's Journal will also have a Part II, comprised of all those Los Angeles 
Convention manuscripts now available and having to do with stereophonic principles 
and equipment. Also included are three articles about basic development and the 
principles of auditory perspective, reprinted from a symposium in the Bell System 
Technical Journal for April 1934 and Electrical Engineering for January 1934. Single 
copies of this material are expected to be available at $1.00 each. 



205 



Book Reviews 



The Science of Color 

Committee on Golorimetry of the Optical 
Society of America, L. A. Jones, Chair- 
man. Published (1953) by Thomas Y. 
Crowell, 342 Fourth Ave., New York 16. 
i-xiii + 340 pp. + 22 pp. references + 
23 pp. glossary-index. 102 color plates + 
40 tables + 102 illus. 7 X 10 in. Price 
$7.00. 

The information contained in The 
Science of Color is background information 
which the good color technologist in any 
field should have. For this reason, the 
book is highly recommended for graduate 
study and research work. 

The Science oj Color can be divided 
roughly into three general sections: 
physical, psychophysical and psycho- 
logical. Two chapters are devoted to 
physical information. One discusses 
radiant energy and its measurement and 
describes the behavior of light as it strikes 
matter and is transmitted or absorbed. 
This type of information is useful in under- 
standing how light is modified by selected 
absorption and thereby becomes colored. 
Another chapter is devoted to the anatomy 
of the eye and physiology of color vision. 
This chapter gives a description of the 
construction of the eye and its various 
component parts and is useful in under- 
standing the perception of color. 

The psychophysical aspects of color 
involve the measurement of the color 
properties of an object and of light in 
order to determine the color effect the 
light will have upon an observer. Three 
chapters are devoted to this extensive 
subject. It is by the methods of measure- 
ment described in this section that the 
engineer is able to evaluate the color of 
objects he fabricates. 

In the psychological section, one chapter 
is devoted to the sensory aspects of color 
and discusses such things as after-images 
and color discrimination. Among many 
other interesting facts it is pointed out 
that color discrimination in children 
improves rapidly up to the age of 25 years 
and is followed by a gradual falling off 
which becomes more pronounced around 
the age of 65. Another chapter is devoted 
to the perceptual and affective aspects of 
color. One of the many subjects discussed 



here is the mode of appearance, and we 
learn for instance that when an artist 
partially closes his eyes to evaluate color 
perception better he is endeavoring to 
separate color from object perception 
and is in effect changing the mode of 
appearance from a surface color to a film 
color. Also in this chapter we learn that 
in motion pictures the "mood" of a story 
can be maintained for a long sequence 
simply by continuing the dominant color. 

The book is unique in that it includes a 
glossary index in which a large number 
of color terms are defined and reference 
given to sections of the book where the 
subject is discussed. 

The technologist or engineer who in his 
daily work is handling materials to produce 
pleasing colors may be disappointed in 
the book in that it does not deal with the 
technology of color. When an engineer 
thinks of color, he is very likely to think 
of the limited aspects of producing colored 
films, colored television screens or colored 
objects which is color technology. Ac- 
tually the science of color embraces a large 
number of fields and consists of all knowl- 
edge concerning the production of color 
stimuli and their visual perception. The 
book quite properly includes all these 
aspects. If the engineer reads this book 
with the idea of getting background 
knowledge in order to understand better 
many of the color phenomena which arise 
in his daily work, he will find it well 
worth while. E. I. Stearns, American 
Cyanamid Co., Calco Chemical Div., 
Bound Brook, N.J. 

"Color" 

From Germany comes an announcement 
of a new journal entitled Color, to be 
concerned with all aspects of color photog- 
raphy, colored light, color v'sion and its 
testing and color sensitometry. The Board 
of Editors includes some of the foremost 
authorities in Germany, such as Manfred 
Richter, E. Engelking, A. Kohlrausch, 
S. Rosch and J. Eggert. The journal 
is to appear in occasional numbers at 
7.80 German marks per number. Full 
information can be obtained from the 
Verlag fur angewandte Wissenschaften 
G.m.b.H., Rheinstrasse 79, Wiesbaden. 



206 



New Members 



The following members have been added to the Society's rolls since those last published. The 
designations of grades are the same as those used in the 1952 MEMBERSHIP DIRECTORY. 



Honorary (H) 



Fellow (F) 



Active (M) 



Associate (A) 



Student (S 



Arthur, James K., Northwestern University 

Mail: 8916 Skokie Blvd., Skokie, 111. (S) 
Bernstein, Robert, Television Engineer, Ameri- 
can Broadcasting Co. Mail: 683 Bradford 

St., Brooklyn 7, N.Y. (A) 
Brossok, William C., Westrex Corp. Mail: 

160 Beach St., Staten Island 4, N.Y. (A) 
Buck, Peter J., Production Engineering 

Manager, Westrex Corp. Mail: 180 Prospect 

St., East Orange, N.J. (A) 
Budd, E. R., Assistant Manager, B. F. Shearer 

Co., 1964 South Vermont Ave., Los Angeles, 

Calif. (A) 
Burton, Don, Radio and Television Station 

Manager, Tri-City Radio Corp., P.O. Box 

271, Muncie, Ind. (M) 
Cahill, Don, Producer, Photographer. Mail: 

5707 W. Lake St., Maywood, 111. (A) 
Chavvaria N., Alvaro, Apartado #1923, San 

Jose, Costa Rica, Central America. (A) 
Chesnes, Albert A., Manager, Television 

Operations, Paramount Pictures Corp. Mail: 

45-2176 St., Elmhurst, N.Y. (M) 
Clay, John P., Engineering Supervisor, WSAZ- 

TV. Mail: 3034 Third Ave., Huntington, 

W. Va. (M) 
Conviser, Benjamin S., Executive, American 

Theatre Supply Corp., 78 Broadway, Boston 

16, Mass. (M) 
Cook, Lewis Clark, Technical Director, Central 

Illinois Telefilms, 810 North Sheridan Rd., 

Peoria, 111. (M) 
Cornberg, Sol, Supervisor of Plant and Facilities 

Development, National Broadcasting Co., 

Inc., 30 Rockefeller Plaza, New York, N.Y. 

(M) 
Edison, Edward, Television Engineer, National 

Broadcasting Co. Mail: 329 Sycamore Rd., 

Santa Monica, Calif. (M) 
Elliott, Lt. Col. Robert D., Motion-Picture 

Technical Staff Officer, U.S. Air Force. 

Mail: 12242 Magnolia Blvd., North Holly- 
wood, Calif. (M) 
Evans, William E., Jr., Television Research 

Engineer, Stanford Research Institute, Stan- 
ford, Calif. (M) 
Fisher, Frank H., General Manager, J. Arthur 

Rank Film Distributor (Canada) Ltd., 277 

Victoria St., Toronto, Canada. (A) 
Goodman, R. Irwin, University of California at 

Los Angeles. Mail: 737 Burchett St., 

Glendale 2, Calif. (S) 
Graziano, Peter S., Motion-Picture Printer 

Operator, Cinecolor Corp. Mail: 3013 

West Via Ceizro, Montebello, Calif. (A) 



Gregory, Howard P., Vice-President, Wilbur 

Machine Co., Inc., 50 Wall St., Binghamton, 

N.Y. (M) 

Grube, Wolfgang Otto, Project Engineer, Re- 
search and Development Division, Mergen- 

thaler Linotype Co. Mail: 130 Harcourt 

Ave., Bergenfield, N.J. (A) 
Hagenau, Scott N., Assistant Chief Engineer, 

WSBT, WSBT-TV, 225 West Colfax Ave., 

South Bend 26, Ind. (A) 
Hansen, William E., Film Technician, Acme 

Film Laboratories. Mail: 3369 Rowena 

Ave., Los Angeles 27, Calif. (M) 
Hoyle, Peter I., Sound Engineer, Information 

Services Dept., Gold Coast Film Unit, P.O. 

Box 745, Accra, Gold Coast, West Africa. 

(A) 
Janetis, Michael, Motion-Picture Cameraman. 

Mail: 100 W. 80 St., New York, N.Y. (A) 
Jordan, Thomas E., Jr., Senior Motion-Picture 

Specialist, U.S. Air Force. Mail: 545 South 

St., Glendale 2, Calif. (A) 
Kane, Henry S., President, North American 

Screw Products Co., Inc. Mail: 1732 North 

California Ave., Chicago, 111. (M) 
Kavlin, Marcos, Kodak Dealer, Casilla 500, 

La Paz, Bolivia. (A) 
Kubicka, Heinz F., Chief Engineer, Television 

Advertising Association, Inc. Mail: 530 

Riverside Dr., Apt. 1C, New York 27, N.Y. 

(A) 
Leiby, Alden M., Chief Engineer, Franklin 

Electronics, Inc. Mail: 7926 Burholme Ave., 

Philadelphia 11, Pa. (M) 
Levy, George M., Jr., Photo Patrol, Cine Speed, 

Inc., Roosevelt Raceway, Westbury, Long 

Island, N.Y. (M) 
Locanthi, Bart N., Research Engineer, 

Acoustical Consultant, Gal-Tech, J. B. 

Lansing Sound Co. Mail: 2552 Boulder Rd., 

Altadena, Calif. (M) 
Morrison, James C., University of California at 

Los Angeles. Mail: 6948 Cedros Ave., 

Van Nuys, Calif. (S) 
Morrison, William A., Sales, Magnetic Sound 

Products, Reeves Soundcraft Corp., 10 E. 

52 St., New York 22, N.Y. (A) 
Muncheryan, Hrand M., Staff Physicist, 

Aerojet Engineering Co. Mail: 1202 Sesmas 

St., Duarte, Calif. (A) 
Nicholson, Elwood J., First Cameraman, 

Director of Photography, Cinematic Pro- 
duction Service, 1123 Lillian Way, Holly- 
wood Calif. (M) 



207 



Niles, Fred A., Vice-President, Director of 
Motion-Picture-Television Division, Kling 
Studios, Inc., 601 North Fairbanks Ct., 
Chicago 11, 111. (M) 

Norman, J. E., West Coast Manager, De Vry 
Corp., 5121 Sunset Blvd., Hollywood 27, 
Calif. (M) 

Orrett, William S., Radio Engineer, Inter- 
national Productions, Ltd. Mail: Wexford 
P.O., Ontario, Canada. (A) 

Palys, Frank, Photo Supplies, 207 Third St., 
Elizabeth, N.J. (A) 

Patterson, Stanley, President and Partner, 
Pampa Electronics Sales Corp. Mail: 1380 
Dermond Rd., Drexel Hill, Pa. (M) 

Regal, Frank R., Film Technician, Warner Bros. 
Studio. Mail: 302 \ Hollywood Way, Bur- 
bank, Calif. (A) 

Ridinger, H. J., Jr., Television Technician, 
KLAC-TV. Mail: 11808 South Ruthelen, 
Los Angeles 47, Calif. (A) 

Ronson, Harry A., Television Workshop of 
New York. Mail: 1510 E. Fourth St., 
Brooklyn 30, N.Y. (S) 

Salas-Porras, Francisco, Assistant Manager, 
Azteca Films, Inc. Mail: 6102 Flores Ave., 
Los Angeles 56, Calif. (A) 

Saxon, Spencer D., Motion-Picture Photog- 
rapher, Audio-Visual Center, Syracuse 
University, Collendale at Lancaster, Syracuse 
10, N.Y. (A) 

Scales, John W., Chief Projectionist, Columbia 
Pictures Corp. Mail: 11622 Hamlin St., 
North Hollywood, Calif. (M) 

Schwab, Don R., Film Producer, Sportsvision, 
Inc. Mail: 550 Veteran Ave., Los Angeles 
24, Calif. (M) 

Signaigo, Frank K., Research Director, E.I. 
du Pont de Nemours & Co., Photo Products 
Dept., Wilmington, Del. (M) 

Snyder, J. Earl, Sound Mixer, Ryder Sound 
Service. Mail: 4755 Columbus Ave., Sher- 
man Oaks, Calif. (M) 

Stableford, John, Projection Equipment Manu- 
facturer. Mail: 45 Latimer Rd., London 
W.ll, England. (A) 



Stickling, John H., Motion-Picture Projectionist, 

Starview Outdoor Theater, Inc. Mail: 

R.R. #2, Box 74, Dundee, 111. (M) 
Stratford, John, Executive Motion-Picture and 

Television Producer, Splendid Films, Inc. 

Mail: 2239 Savannah Ter., S.E., Washington 

20, D.C. (A) 
Tami, Joseph, Jr., University of California at 

Los Angeles. Mail: 3919 Third Ave., 

Los Angeles 8, Calif. (S) 
Tate, John C., Printer Foreman, Acme Film 

Laboratories. Mail: 12208 Oxnard St., 

North Hollywood, Calif. (A) 
Wallin, Walter, Optical Physicist. Mail: 20226 

Arminta St., Canoga Park, Calif. (A) 
White, Roy A., Television Engineer, Studio 

Supervisor, Paramount Television Productions, 

Inc. Mail: 913 North Frederic, Burbank, 

Calif. (A) 
Wiener, Alan J., Manager, Visual Advertising 

Associates TV. Mail: 24 Lyons St., New 

Britain, Conn. (A) 
Wright, Walter W., Design Engineer. Mail: 

1822 Essex Ave., Linden, N.J. (A) 
Young, Blanche, University of Southern Cali- 
fornia. Mail: 71 1 W. 35 PL, Los Angeles 7, 

Calif. (S) 

CHANGES IN GRADE 

Buxbaum, Morton L., (S) to (A) 
Clarke, Charles G., (A) to (M) 
Dodge, Glenn T., (S) to (A) 
Moorhouse, Anson C., (A) to (M) 
Sarber, Harry, (A) to (M) 
Sloan, Melvin, (S) to (A) 
Woolsey, Ralph A., (A) to (M) 

DECEASED 

Harvey, Douglas G., University of Southern 

California. Mail: 1846 South Cochran PI., 

Los Angeles 19, Calif. (S) 
Oakhill, Frederic E., President, Prismacolor 

Pictures, Inc. Mail: 711 Linden Ave., 

Wilmette, 111. (M) 



SMPTE Lapel Pins 



The Society has available for mailing its gold and blue enamel lapel pin, with a screw 
back. The pin is a ^-in. reproduction of the Society symbol the film, sprocket and 
television tube which appears on the Journal cover. The price of the pin is $4.00, 
including Federal Tax; in New York City, add 3% sales tax. 



SMPTE Officers and Committees: The roster of Society Officers and the 
Committee Chairmen and Members were published in the April Journal. 



208 



Chemical Corner 



Edited by Irving M. Ewig for the Society's Laboratory Practice Committee. Suggestions should 
be sent to Society headquarters marked for the attention of Mr. Ewig. Neither the Society nor the 
Editor assumes any responsibility for the validity of the statements contained in this column. They 
are intended as suggestions for further investigation by interested persons. 



German Developing The Union Color 
Machines Developing Ma- 

chine constructed 

for both the new negative/positive color 
processes and black-and-white is a low-cost 
machine reported capable of turning out 
twice the footage of our previous machines. 
Of duplex design, it can be had with 35mm 
or 16mm on each side or a combination of 
these. The drive mechanism is at the 
bottom and the film is transported by 
friction rollers. The tanks are lined with 
a thermoplastic material which is com- 
pletely noncorrosive in the strongest 
bleach. The temperature of the solutions 
is controlled by heat exchangers located 
in the tanks themselves. The agents are 
Movie Technicians, 55 Poplar Ave., 
Hackensack, N. J. 

Regeneration of Ferri- U.S. Patent 

cyanide Bleach Baths 2,611,699 makes 
claims for an- 
other scheme of the conversion by bromine 
of ferrocyanide back to the active ferri- 
cyanide and also supplies additional 
bromide in the process. The bromine is 
added in the required quantity as deter- 
mined by analysis in the form of a hypo- 
bromite or of a bromate. 

Hazardous Chemicals With the recent 

in Photography increase in the 

chemical activity 

in the motion-picture laboratory arising 
from color, 3-D and other new processes, 
a timely article in the British Journal of 
Photography, October 8, 1952, pp. 380-81, 
deals with dangerous chemicals that may 
be encountered in photography. Allergic 
reaction to chrome salts, developing and 
cleaning agents, especially the chlorinated 
ones near a glowing cigaret or flame 
hazards are mentioned along with other 
dangers which may be expected in experi- 
mental laboratories and darkrooms. 

Sepia Tone Control Claims are made 
in U.S. Patent 

2,607,686 for controlling the coldness of 
sepia tones by the adjustment of the 



bromide content of the developer. The 
higher the bromide the colder the tone. 

Another Approach to At the Naval Air 
Silver Recovery and Station at Ana- 
Fixer Rejuvenation costia, D.C., ex- 
hausted fixer is 

collected in a storage tank. When the 
liquid reaches a certain level an electrolytic 
silver recovery unit is automatically 
started. Ten stainless-steel cathodes collect 
the silver while the treated bath, which is 
rejuvenated at the rate of 90 gal/hr, is 
tested, readjusted and mixed with 20% 
fresh solution. * A more complete descrip- 
tion of this process is given in American 
Photography, December 1952, p. 12. 

A Transparent Pipe Mills 111 is a 
transparent plastic 

pipe of cellulose acetate butyrate ranging 
in size from 5 to 4 in. It permits observa- 
tion of processes and is highly resistant to 
attack by chemical solutions. Pipe sections 
are joined by a solvent cement that 
produces a leakproof homogeneous bond. 
No threading or special tools are required 
and it is cut with a hand saw. Setups 
may be dismantled and all components 
used repeatedly. The tubing is tough, 
shatterproof and requires a minimum of 
support. The manufacturer is Elmer E. 
Mills Corp., 2930 North Ashland Ave., 
Chicago 13, 111. 

A Greaseless Grease "Molynanul" is a 
molybdenum di- 

sulfide enamel which can be brushed or 
sprayed on any surface to give a very thin 
film lubricant. It puts a lustrous, hard, 
greasy-feeling but clean, coating from a 
fifth to a half-thousandth of an inch thick. 
Except in extreme cases normal clearances 
need not be disturbed as the final thickness 
is no greater than the allowance for oil. 
Its applications are numerous and might 
be investigated as a lubricant for motion- 
picture film. The manufacturer is The 
Lackrey Company, Southampton, N.Y. 



209 



New Products 



Further information about these items can be obtained direct from the addresses given. As in the 
case of technical papers, the Society is not responsible for manufacturers' statements, and publica- 
tion of these items does not constitute endorsement of the products. 

In the optical field, the new company 
will be prepared to supply the require- 
ments of a variety of laboratory and com- 
mercial needs to which optical-quality 
fused quartz is suited. Among these are 
precision lenses, optical flats, projection 
lenses which operate under conditions of 
great heat and thermal shock, and any 
optical equipment which must transmit 
a high degree of ultraviolet radiation. 




The first commercial production in the 
U.S. of optical-quality fused quartz in- 
tended for use in electronic computers, 
scanners, etc., is announced by Hanovia 
Chemical & Mfg. Go. The new quartz 
will be manufactured by Optosil Inc., 
Hillside, N.J., a newly formed subsidiary 
of Hanovia. 

A major electronic application of Optosil 
quartz will be for ultrasonic solid delay 
lines whose function is to create a time 
delay of electrical impulses for predeter- 
mined periods. In such delay lines, the 
electromagnetic waves are first converted 
to ultrasonic waves through a piezoelectric 
transducer. These amplitude-modulated 
ultrasonic waves are then passed through 
a quartz medium, after which they are 
reconverted to an electrical signal whose 
modulation is identical with the input. 
Because of the ratio of 100,000:1 between 
the velocity of the electromagnetic waves 
and that of the sonic waves in the quartz 
medium, a significant time delay results. 
Relatively long delay periods in a small 
space can be produced by the use of 
multiple reflection paths (in two or three 
dimensions) within the quartz medium. 




An electric film timer, tradenamed the 
Camart, has been designed and marketed 
by The Camera Mart, Inc., 1845 Broad- 
way, New York 23, N.Y., for use in 
motion-picture editing, dubbing, narra- 
tion, script timing and commenting. The 
unit will read elapsed time in minutes 
and tenths and will record total footage 
for 16mm or 35mm motion-picture film. 
The timer may be wired to the projector 
or recorder to start automatically, or may 
be used independently. It may be started 
and stopped any number of times, and the 
time or footage indicators may be reset 
separately. The mechanism is removable 
from the chassis for mounting in a rack 
assembly. Dimensions are 4^ in. high 
by 4 in. wide by 1\ in. long, weight 4 Ib. 
A combination timer for either 16mm or 
35mm footage with time indicator is 
priced at $125. A combination 16mm 
and 35mm footage counter is also priced 
at SI 25. A single 16mm or 35mm 
footage counter sells for $75 



210 



A new filter alignment and cooling mecha- 
nism has just been put into production 
by the Drive-In Theatre Mfg. Co., Division 
of DIT-MCO, Inc., 505 W. Ninth St., 
Kansas City 5, Mo. The metal housing is 
designed to be mounted permanently at 
the porthole. The dimensions of the 
entering and leaving sides are sufficient 
to accept the wide projection beam of 
CinemaScope and Cinerama. The depth 
is such that it will not interfere with the 
projector, even at extreme angles, or with 
large magazines. The top plate of the 
housing is flat for blower mounting, and 
the bottom plate is sloped down at a 
25 angle, to accept projection beams up 
to this angle. Where the need is for a 
greater pitch, any angle can be made. 
The blower has a capacity of 100 cfrn 
with a 3050-rpm motor. The duct and 
spreader are metal, and the spreader is 
designed to distribute air over the entire 
surface of the filter. The framing mecha- 
nism is designed so that, after proper 




alignment of the filter, it can be perma- 
nently locked to that alignment. The 
eight adjustments for the filter are in and 
out; up and down; top or bottom in and 
out at angles; right and left angles to 
horizontal. 



Employment Service 



These notices are published for the service of the membership and the field. They are inserted for 
three months, and there is no charge to the member. 



Positions Wanted 

Experienced motion-picture production 

man desires connection with film company 
as producer-director or production man- 
ager. During past 12 yrs. experience 
includes directing, photographing, editing, 
recording and processing half-million feet 
finished film, including educational films, 
industrials, TV spots, package shows for 
TV and experimental films. University 
graduate, married, twenty-nine years old; 
good references. Locate anywhere conti- 
nental U.S. Write Victor Duncan, 8715 
Rexford Drive, Dallas 9, Tex. 

Film Production/Use: Experienced in 
writing, directing, editing, photography; 
currently in charge of public relations, 
sales and training film production for 
industrial organization. Solid film and 
TV background, capable administrator, 
creative ability, degree. References and 
resume upon request. Write FPF, Room 
704, 342 Madison Ave.. New York 17, 
N.Y. 



Positions Available 
Wanted: Optical Engineer for permanent 
position with manufacturer of a wide 
variety of optics including camera objec- 
tives, projector, microscope and telescope 
optics, etc. Position involves design, de- 
velopment and production engineering. 
Send resume of training and experience to 
Simpson Optical Mfg. Co., 3200 W. Carroll 
Ave., Chicago 24, 111. 

Wanted: Personnel to fill the 4 classifica- 
tions listed below, by the Employment 
Office, Atten: EWACER, Wright-Patter- 
son Air Force Base, Ohio: 



Film Editor, GS-9: Must have 5 yrs. 
experience in one or more phases of motion- 
picture production. Experience must 
include at least 1 yrs. motion-picture 
film editing with responsibility for syn- 
chronization of picture, narration, dia- 
logue, background music, sound effects, 
titles, etc. $5060 yr. 



211 



Photographic Processing Technician gressively responsible experience in motion- 
(Color) GS-7: 6 yrs. progressively re- picture photography and/or photographic 
sponsible experience in motion-picture laboratory work, involving essential opera- 
photography and/or photographic labora- tion of film processing. $4205 yr. 
tory work, involving essential operation 

of film processing. Eighteen months of Photographic Processing Technician 

this experience must have involved proc- (Black-and- White) GS-5: 2 yrs. pro- 

essing of color film. $4205 yr. gressively responsible experience in motion- 
picture photography and/or photographic 

Photographic Processing Technician laboratory work, involving essential opera- 

( Black-and- White) GS-7: 6 yrs. pro- tion of film processing. $3410 yr. 



Meetings 



Society of Motion Picture and Television Engineers, Central Section Meeting, Sept. 11 

(tentative), WLW-D, Dayton, Ohio 

Illuminating Engineering Society, National Technical Conference, Sept. 14-18, Hotel 

Commodore, New York, N.Y. 

The Royal Photographic Society's Centenary, International Conference on the Science 
and Applications of Photography, Sept. 19-25, London, England 

National Electronics Conference, 9th Annual Conference, Sept. 28-30, Hotel Sherman, 

Chicago 

74th Semiannual Convention of the SMPTE, Oct. 5-9, Hotel Statler, New York 

Audio Engineering Society, Fifth Annual Convention, Oct. 14-17, Hotel New Yorker, 

New York, N.Y. 

Society of Motion Picture and Television Engineers, Central Section Meeting, Oct. 15 

(tentative), Chicago, 111. 

Theatre Equipment and Supply Manufacturers' Association Convention (in conjunction 

with Theatre Equipment Dealers' Association and Theatre Owners of America), 

Oct. 31-Nov. 4, Conrad Hilton Hotel, Chicago, 111. 

Theatre Owners of America, Annual Convention and Trade Show, Nov. 1-5, Chicago, 111. 
National Electrical Manufacturers Association, Nov. 9-12, Haddon Hall Hotel, Atlantic 

City, N.J. 

Society of Motion Picture and Television Engineers, Central Section Meeting, Nov. 12 

(tentative), Chicago, 111. 

The American Society of Mechanical Engineers, Annual Meeting, Nov. 29-Dec. 4, 

Statler Hotel, N.Y. 

Society of Motion Picture and Television Engineers, Central Section Meeting, Dec. 10 

(tentative), Chicago, 111. 

American Institute of Electrical Engineers, Winter General Meeting, Jan. 18-22, 1954, 

New York 

National Electrical Manufacturers Assn., Mar. 8-11, 1954, Edgewater Beach Hotel, 

Chicago, 111. 

Optical Society of America, Mar. 25-27, 1954, New York 

75th Semiannual Convention of the SMPTE, May 3-7, 1954, Hotel Statler, Washington 
76th Semiannual Convention of the SMPTE, Oct. 18-22, 1954 (next year), Ambassador 

Hotel, Los Angeles 

77th Semiannual Convention of the SMPTE, Apr. 17-22, 1955, Drake Hotel, Chicago 
78th Semiannual Convention of the SMPTE, Oct. 3-7, 1955, Lake Placid Club, Essex 

County, N.Y. 

The Seventh Congress of the International Scientific Film Association will be held 
September 18-27 in the National Film Theatre and Royal Festival Hall, London S. E. 1. 
A Scientific Film Festival will be held, and in addition, meetings will be held by the 
Permanent Committees on Medical, Research, Technical and Industrial Films. There 
will be special sessions on the technique and application of films in medicine. 

212 



The Development of High-Speed 
Photography in Europe 



By HUBERT SCHARDIN 



The main features of European high-speed photographic instrumentation are 
described, including cameras using stationary film, those with intermittently 
or continuously moving film, and those incorporating the film drum. Methods 
of lighting high-speed photography with various spark arrangements are 
discussed. 



OINCE it is hardly possible in a brief 
review to present a total picture of the 
development of high-speed photography 



in Europe, an attempt is made here to 
select data showing the general trend 
in the field during the past sixty years. 



MECHANICAL METHODS 



Cameras With Fixed Film Strip 

It is a little -known fact that as early as 
1892 the Prussian Armaments Testing 
Commission (Preussische Artillerie Prii- 
fungskommission) constructed a camera 
in which the film was stationary, with a 
speed of 1000 frames/sec, the exposure 
time of each frame being 10~ 4 sec. 

Figure 1 shows schematically the 
principle of this camera, which was cer- 
tainly influenced by the work of Muy- 
bridge in California. For this early 
venture in high-speed photography, 12 
cameras were set along the quarter-arc 



Presented on October 8, 1952, at the Soci- 
ety's Convention at Washington, D.C., by 
Hubert Schardin, Laboratoire de Re- 
cherches, St. Louis, France. Residence: 
Rosenstrasse 10, Weil am Rhein, Baden, 
Germany. 

(This paper was received in revised form 
June 1, 1953.) 



of a circle. Exposure was accomplished 
by a slit in a rotating disk with a diameter 
of 230 cm and a speed of 20 rps. The 
velocity of the slit was therefore the aston- 
ishing one for that day of 145 m/sec. 

At that time the focal length of lenses 
was considerably greater than is used 
today, so that the distance between two 
cameras was 14.5 cm, resulting in a repe- 



12 cameras 



14,scmf 




1000 frames p~,c. 
exp. time n'*sec. 



Fig. 1. Prussian Armaments Testing 
Commission high-speed camera (1892). 



September 1953 Journal of the SMPTE Vol. 61 



273 




be 
' 



274 



September 1953 Journal of the SMPTE Vol. 61 



tition rate of 1000 frames/sec. With 
modern short focal-length lenses, the 
same arrangement would produce a 
correspondingly higher framing rate. 
Lucien Bull (a colleague of Marey, the 
famous French pioneer in cinematog- 
raphy) built a similar camera in Paris in 
1933. It was capable of taking 50 pic- 
tures on a single 13 X 18 cm plate at a 
speed of 3000 frames/sec. Figure 2, 
showing in successive stages the entry 
of a falling ball into water, is an example 
of the work of this camera. 

About 1930, the firm of Askania in 
Berlin constructed a camera with 12 
lenses; however, there were 13 slits in the 
disk, so that exposure was complete after 
a 30 rotation. The framing rate was 
15,000 frames/sec. 

The repetition rate increases as the 
lens diameters decrease. Therefore, 
with a 1-mm slit, operating at 100 m/sec, 
the exposure time per frame would be 
10~ 5 sec, provided each exposure starts at 
the end of the preceding one. Under 
these conditions it should be possible to 
attain a rate of 100,000 frames/sec. 

This has been achieved in the English 
Marley camera (Fig. 3), which has 59 
lenses, and mirrors through which 59 
images are reflected on a film strip. 1 
The effective aperture is//27; therefore 
only very bright objects may be photo- 
graphed successfully. There are 16 
slits in the rotating disk, requiring a 
rotation of 22.5 for exposure of all 59 
frames. 




59 lenses If; 271 



(0,8mm) 




Cameras With Rotating Light Beam 

The next development is a simple one. 
The revolving mechanical slit disk is 
replaced by a rotating light beam, the 
speed of which can be, of course, in- 
creased considerably over that of the 
disk. The American Miller and Bowen 
cameras apply this principle, and it has 
also been applied in Europe. 

First should be mentioned a design of 
the German firm of Rheinmetall (1944). 
This camera (Fig. 4) has an annular ring 
with 50 fixed lenses and a fixed film 
strip. The frames are exposed in suc- 
cession by means of a rotating mirror. 
This method requires that the image on 
the film be stationary during exposure; 
therefore the intermediate image must 
be on the mirror. Because of the war, 
Rheinmetall was unable to complete the 
development of this camera, but the work 
has been carried on by the British Royal 
Naval Scientific Service. 2 

Another application of this principle is 
that of Bartels (Fig. 5). He substitutes 




Fig. 4. The Rheinmetall camera (1944). 



Fig. 3. The Marley camera 
(100,000 frames/sec) (1949). 




Fig. 5. The Bartels camera (1949). 
Schardin: High-Speed Photography in Europe 



object 




I 
light -source 



rotating mirror 



camera 



Fig. 6. Mechanical light control of the multiple-spark camera 
(Schardin, 1949). 



fixed mirrors for the required number of 
lenses and uses only one object lens. 
Again an intermediate image is formed 
on the rotating mirror. Bartels' camera 
is very economical, since it can be set up 
with ease using the normal equipment of 
a research laboratory. 

It is often very useful, particularly 
when schlieren illumination is required, 
to use a multi-lens system for mechanical 
light control. The resulting system 
behaves like a multiple-spark camera, 
but uses only one light source (Fig. 6). 
This may be regarded as the continua- 
tion of the multiple-spark principle into 
the region of lower framing rates. 

Cameras With Intermittently 
Moving Film 

All the cameras so far mentioned have 
the disadvantage of producing only a 
limited number of frames. The first 
remedy is the intermittent displacement 
of the film when exposure of a given seg- 
ment has been completed; i.e. during 
exposure, and as long as the shutter is 
open, the film is at rest. It is interesting 
to note that Marey, in Paris in 1885, 
obtained 110 normal-sized frames/sec 
in his photographic gun. Even today 
it is impossible to achieve much more 
than double this rate, since the velocity 
of intermittently moved film cannot 
normally exceed 5 m/sec. Figure 7 
shows an original Marey series of a 
dog in motion. The European Vinten, 
Debrie and Askania cameras produce 
about 250 frames/sec on 35mrn film. 
It is perhaps surprising that intermittent 



cameras attaining the possible maximum 
for 16mm and 8mm film do not yet 
exist. It is interesting in this respect to 
mention the development by the Swedish 
Armament Department of an inter- 
mittent-motion camera with a speed of 
more than 1,000 frames/sec. The inter- 
mittent film motion is achieved by a 
film drive consisting in part of two 
splined rubber rollers. 

Cameras With Continuously 
Moving Film 

The first important camera using the 
principle of optical compensation and 
taking pictures on continuously moving 
film is certainly the "Zeitlupe" of Leh- 
mann, built in 1916 by Ernemann and in 
1928 by Zeiss Ikon. The use of the 
principle of compensation with a rotating 
polygonal mirror is schematically shown 
in Fig. 8. 

It is probably unnecessary to describe 
this well-known camera in detail, since 
its use is now so widespread. It was 
first used for ballistics studies during 
World War I. At that time it had a 
speed of only 500 frames/sec. Rumpff 
proposed in 1916 to increase this rate by 
using three cameras in parallel connec- 
tion, with an adequate phase shift of 
exposure times. Such a triple camera 
was subsequently developed, and others 
similar to it followed. 

It is worth pointing out that the quality 
of the picture sequence produced by 
several cameras in this way is inferior to 
that produced by a single camera with a 
correspondingly higher framing rate. If 
the exposure time of one frame is greater 



276 



September 1953 Journal of the SMPTE Vol. 61 




Fig. 7. Part of a sequence taken by Marey (120 frames/sec). 
Schardin: High-Speed Photography in Europe 



277 



Q 








Fig. 8. The "Zeitlupe" camera (Leh- 
mann, 250-500 frames/sec; Zeiss Ikon, 
1500 frames/sec). 

than the reciprocal of frame frequency, 
the blur caused by motion in the object 
is magnified and impairs clarity. In 
practice, three cameras in parallel 
connection have a time resolution only 
37% higher than that of one of them 
operating alone. 

Optical compensation can also be 
effected in other ways. In a number of 
cameras it is achieved with rotating 
prisms or lenses. 

A camera employing an octahedral 
prism is the Rotax designed by Askania. 3 
Though it produces only 600 frames/sec 
on normal film, it is worthy of mention 
since its images have fairly good resolu- 
tion and its weight is only 13 Ib. It can 
be hand-held during operation. 

Optical compensation by means of 
rotating lenses has been applied since 
1926 chiefly by Thun, whose cameras 
have been commercially produced by 
Askania and A. E.G. In France there 
are two similar cameras manufactured 
by Merlin-Gerin-Debuit of Grenoble. 
One is designed for 16mm film and has 
a speed of 3000 frames/sec; the other, for 
8mm film achieves 6000 frames/sec. 

An advantage of the A. E.G. camera is 
the fact that its lens disk is interchange- 
able with a slit disk. Moreover, each 
frame can be divided into a great number 
of small frames, up to 80, each of them 
only 1.8 X 3 rum in size. Thus an in- 
crease in exposure rate up to 80,000 
frames/sec is achieved. 

As early as 1936, Thun suggested the 
possibility of achieving practically con- 




Fig. 9. Frame-division method 
of time resolution. 



tinuous time resolution. As is seen in 
Fig. 9, a narrow slit traverses six individ- 
ual frames, each of which is slightly 
displaced longitudinally (on the time 
axis). The slit therefore simultaneously 
exposes a different segment of each of 
the six frames. Were we to view these 
frames, not much time resolution would 
be evident, since the exposure times 
of the frames overlap considerably. 
However, by reconstituting into one 
picture all the segments exposed at the 
same instant, very good time resolution 
can be achieved. 

Decreasing the size of the slit and in- 
creasing the number of frame divisions 
will bring about still better time resolu- 
tion, but with considerable sacrifice in 
image quality. Therefore, in using this 
method it is important to fix optimal 
conditions for both these factors. 

Drum Cameras 

If a great number of frames is not re- 
quired, one strip of film may be fixed on a 
rotating drum and the complexities of 
moving film avoided. 

The first drum camera with optical 
compensation by mirrors in practical 
use is probably Rumpff 's model of about 
1928. The frame was 120 mm broad 
by 7 mm high, the speed 5000 frames/ 
sec, and the length of film allowed for 
50 frames. 

The MGD firm of Grenoble, France, 
has manufactured a drum camera with 
rotating lenses, the arrangement of 



278 



September 1953 Journal of the SMPTE Vol. 61 




Fig. 10. The Merlin-Gerin-Dcbuit camera. 

which is worth study (Fig. 10). 4 The 
film drum and the lens ring are one com- 



pact piece, rotating together. Optical 
compensation is provided by the differ- 
ence between the tangential velocities of 
lenses and film. Three rings of lenses are 
set parallel in the camera, each ring 
taking 250 pictures. The speed is 
33,000 frames/sec for each ring and 
would be 100,000 frames/sec for the 
three rings were it not for the fact that 
the exposure time for one frame is greater 
than the time difference between two 
parallel frames a consideration which 
greatly reduces effective speed. 



ELECTRICAL METHODS 



The second group of photographic 
instrumentation tools is based on the 
electrical discharge of a condenser. 
To study a rapid phenomenon, it is not 
always necessary to use a high picture 
repetition rate; one sharp picture with 
sufficient detail sometimes gives excellent 
information. 

Ernst Mach, about 1880, first made 
use of the electrical spark discharged from 
a condenser to photograph high-speed 
phenomena such as shock waves, ex- 
plosions and moving projectiles. C. 
Granz continued this work, achieving 
bright, brief sparks which made his 
shots, even by today's standards, models 
of fine still-picture technique (Figs, lla 
and lib). 

The early simple form of electrical 
discharge in air is still used for photo- 
graphic lighting, particularly when brief 
flashes are required. But much has 
been done in the last twenty years to 
increase the optical effectiveness of this 
method. Two factors have been im- 
portant in this development: (1) the 
substitution of krypton or xenon for air; 
and (2) the prolongation of the dis- 
charge channel. Using these two fac- 
tors, Harold E. Edgerton in America 
devised the first electrical flashlamps. 

In our German laboratory, during 
the war, the guided-spark principle was 
used to prolong the discharge path. It 
becomes possible, for example, to in- 



crease the length of a 40,000-v spark 
from 15 mm (sphere) to 800 mm, and 
to increase brightness by the factor 10. 
An energy of 800 wattsec produced a 
guided spark in air which illuminated 
a surface 4 X 4 m sufficiently to take 
pictures with a Kerr-cell camera, the 
exposure time being 1 /zsec. These 
guided-spark tubes, filled with xenon, 
are now produced under the name 
"Defatron" by the French Central 
Armaments Laboratory. Major Naslin 
has described this instrument in detail. 6 

Cameras Using Pulsed Spark Gaps 

There are two methods of illuminating 
a motion-picture subject with sparks: 
(1) by flashing a series of sparks between 
the same electrodes; and (2) by the use 
of a multiple-spark gap. The first 
method encounters some difficulty such 
as image separation and the removal of 
ionization in the spark gap. 

The simplest method of controlling 
the spark is a mechanical one. Lucien 
Bull in 1904 constructed the first spark 
camera, using this means (Fig. 12). 
With a rotating switch and an inductor 
he produced 2000 sparks/sec ; 50 frames 
of normal size were taken on a rotating 
drum. The energy of each spark was, of 
course, not very great. 

In 1905 Kranzfelder and Schwinning 
successively discharged 10 condensers 
through a single spark gap by means of a 



Schardin: High-Speed Photography in Europe 



279 




Fig. lla. Schlieren exposure of two 
projectiles fired simultaneously. 



Fig. lib. Projectile 
after exit of the nozzle 
shock wave. 



September 1953 Journal of the SMPTE Vol. 61 




O 

o 
o 



r r 



1 
I 



Fig. 12. The Lucien Bull 
spark camera (1904). 

rotating switch. This principle is some- 
times made use of today, as in the French 
LCA camera, which operates at a speed 
of up to 10,000 frames/sec. 

Cranz's "Ballistics Cinematograph" 
of 1909 (Fig. 13) applied yet another 
principle. Here an oscillator feeds a 
pulse network. The condenser dis- 
charges at each half cycle at a frequency 
of 2,500 cycles/sec. The speed of the 
camera is 5000 or 10,000 frames/sec, 
using a rotating drum. Cranz used this 
camera often and successfully for the 
study of ballistics problems. 

Another way of producing a series of 
sparks is through the alternating charge 
and discharge of a condenser (Fig. 14). 

In 1912 Schatte used a resistance for 
spark control, attaining 50,000 sparks/- 
sec. In the same year Glatzel applied 
the principle of spark telegraphy with a 
result of 100,000 sparks/sec. 

Yet a better method is the use of an 
inductance to control condenser-dis- 
charge (Toepler), since this involves no 
loss of energy. The operation of this 





Schatte 



Toepler 




Glatzel 
Fig. 14. Methods of spark control. 




Fig. 13. The Cranz 'Ballistics 
Cinematograph" (1909). 

arrangement has been calculated in re- 
cent years by Schering, Vollrath and 
Neubert. 

Repeated flashing of a single spark 
requires the separation of frames on the 
film, which makes high speed difficult to 
achieve (Fig. 15). 

A film laid on the outside of a drum 
can achieve a velocity of 120 m/sec, 
and it is possible for a film with frames 
10 mm high to attain 12,000 frames/sec. 
If the same film is laid on the inside of 
the drum, up to 25,000 frames/sec may 
be reached. A rotating mirror in the 
center of a fixed drum could produce a 
maximum rate of about 170,000 frames/- 
sec, but in this case a satisfactory flash 
of sufficient energy in the single spark 
gap is difficult to achieve, and the finite 



film (Km long) 




120m/sec. 



Cranz 1912 




230m/sec. 
rotdttny drum 




1700 m/sec -max 
firlOOOOOr.ps. 



L.Bul/1922 



rotating mirror 



Fig. 15. Methods of frame separation 
on film. 




Fig. 16. The Cranz-Schardin 
multiple-spark camera (1928). 



Schardin: High-Speed Photography in Europe 



281 




Fig. 17. Selection from a sequence taken with the Cranz-Schardin multiple-spark 
camera showing the reflection of a shock wave in an ellipsoid (30,000 frames/sec). 



282 



September 1953 Journal of the SMPTE Vol. 61 




Fig. 18. Selection of sequence taken with Cranz-Schardin multiple-spark camera 
showing fracture of thin membrane used in a shock tube (80,000 frames/sec). 



duration of the spark 
cause blurring. 



ID- 6 sec) will 



The Multiple-Spark Camera 

For high-speed photography there- 
fore, the multiple-spark camera (Fig. 16) 
is preferred. Some of its advantages 
are as follows: 

1. Exposure rates of 10 6 frames/sec and 
more present no difficulties. 

2. The picture size does not depend on 
the exposure rate and can be large 
enough to show any data needed. 

3. No moving parts are necessary, ex- 
cept perhaps for time measurement. 



The shortcomings of the multiple- 
spark camera are, chiefly: 

1 . The limited number of frames which 
can be taken. 

2. The presence of parallax. 

3. The impossibility of photographing 
self-luminous phenomena. 

In spite of these limitations, however, 
the multiple-spark camera is capable of 
such extraordinarily exact photography 
as to make it a most useful tool for photo- 
graphic instrumentation. The time dif- 
ference between two sparks can be meas- 
ured with an accuracy of more than 
10" 7 sec, and the precision in location 



Schardin: High-Speed Photography in Europe 



283 



schlieren- 
mirror 



multiple -spark 
arrangement 




ultra-short 
light -source 



Fig. 19. Optical arrangement of ultra high-speed motion-picture camera based on 
Gran z-Schar din system using velocity of light (1949). 



of a point in the object is about 0.1 mm. 
The error caused by parallax may be 
avoided by photographing a calibration 
grid on the same plate. Some idea of the 
applications of the multiple-spark camera 
is given in Figs. 17 and 18. 

The usual electrical method of trig- 
gering successive sparks will produce a 
maximum of 10 7 frames/sec. If it is 
possible to flash only one spark of sufficient 
brightness, and shorter than 10~ 7 sec, 
the optical arrangement shown in Fig. 1 9 
will produce a higher exposure rate. 

Before entering the camera, the light 
of the spark is reflected several times by 
two auxiliary mirrors. After each two 
reflections comes the next light beam, 
the time delay being dependent on the 
velocity of light and the focal length 
of the auxiliary mirrors. An exposure 
rate of about 10 9 frames/sec appears to 
be possible. 



Kerr-Cell Cinematography 

The separation of pictures in the 
multiple-spark camera is based on the 
fact that an image of the multiple sparks 
is formed in the corresponding lenses. 

This principle does not function (a) 
in daylight, (b) if the object is self- 
luminous, or (c) if the object is to be 
studied in reflected light. 

If any of these conditions must be met, 
the Muybridge equipment, as described 
above, is used, but with Kerr-cell shut- 
ters. In our laboratory, during the 
war, we used eight Kerr cells, of which 
two were used jointly to take stereo- 
scopic pictures. The Kerr cells had a 
37-mm aperture and were controlled by 
40,000 v. When objects were to be 
photographed in daylight or by re- 
flected light a guided spark was flashed 
to supply the light necessary for an ex- 



284 



September 1953 Journal of the SMPTE Vol. 61 




Fig. 20. Stereoscopic Kerr-cell exposure of a bursting shell filled 
with small projectiles. 



posure time of about 1 jtsec. In each 
case two Kerr cells formed an electrical 
unit; the time difference between the 
opening of two successive shutters could 
be regulated from 1 /zsec on up. Figure 
20 is an example of the results achieved 
by this process. 



methods of triggering or of the use of 
X-ray flash sources has necessarily been 
omitted. It is hoped that this brief 
summary will have given American 
engineers at least a broad general idea 
of European high-speed camera achieve- 
ments. 



Image-Converter Photography 

Another possible constituent of the 
electrooptical shutter is the image con- 
verter, known in the field of television. 
In collaboration with the A. E.G. re- 
search laboratory, E. Fiinfer of the 
Laboratoire de Recherches, developed 
(1940) a convenient converter tube 
arrangement. Photographs thus pro- 
duced were somewhat inferior to those 
made using the Kerr-cell technique, but 
further research, such as that now being 
made by Courtney-Pratt in England, 
may bring about improvement. 

In a review such as this it is impos- 
sible to mention every aspect of Euro- 
pean high-speed photographic develop- 
ment; among other matters, mention of 



References 

1. G. A. Jones and E. D. Eyles, "Recent 
British equipment and technique for 
high-speed cinematography," Jour. 
SMPTE, 53: 502-514, Nov. 1949. 

2. W. Deryck Chesterman, "History and 
present position of high-speed photog- 
raphy in Great Britain," Jour. SMPTE, 
60: 240-246, Mar. 1953. 

3. Addendum to Progress Committee 
Report: Developments in Germany, 
Jour. SMPTE, 60: 680-687, June 1953. 

4. Paul M. Gunzbourg, "High-speed mo- 
tion picture cameras from France," 
Jour. SMPTE, 58: 256-265, Mar. 1952. 

5. P. Fayolle and P. Naslin, "Simple 
electronic devices for high-speed photog- 
raphy and cinematography," Jour. 
SMPTE, 60: 603-626, May 1953. 



Schardin: High-Speed Photography in Europe 



285 



A Microsecond Still Camera 



By HAROLD E. EDGERTON and KENNETH J. GERMESHAUSEN 



A shutter with an effective open time of about 1 jusec is described which was 
specially designed to photograph high explosives during detonation. Pre- 
cision adjustment of the exposure instant by a time-delay circuit triggered 
by the explosion light is used for synchronization. Optical systems of focal 
lengths of 6 in. to 6 ft have been employed. Examples are given of pentolite 
and TNT explosions. 



E 



IXPERIMENTS with high explosives 
using a previously described mag- 
netooptic shutter* indicated that a 
shorter exposure time would be advan- 
tageous in studying high-velocity shock 
waves and flame fronts. Accordingly 
the equipment herein described was de- 
signed with every effort to obtain a sim- 
ple, rugged field instrument with a l-/*sec 
shutter open time. 

The Magnetooptic Shutter 

The complete camera assembly as 
used for field work is shown in Fig. 1. 
The microsecond shutter is located in the 



Presented on May 1, 1953, at the Society's 
Convention at Los Angeles by Harold E. 
Edgerton (who read the paper) and Ken- 
neth J. Germeshausen, Edgerton, Germes- 
hausen & Grier, Inc., 160 Brookline Ave., 
Boston, Mass. 

(This paper was received March 27, 1953.) 
* Harold E. Edgerton and Charles W. 
Wyckoff, "A rapid action shutter with no 
moving parts," Jour. SMPTE, 56: 398-406, 
Apr. 1951. 



square-shaped aluminum casting. On 
the back of this casting is a mounting 
position to accept a 4 X 5 in. Eastman 
view camera, although almost any 
camera can be used with slight modifica- 
tion of the base. Provision is made on 
the back side of the magnetooptic shutter 
to fit the lens ring of a Wollensak shutter 
containing a 163-mm focal-length lens. 
The "X" synchronizing contacts on the 
Wollensak shutter enable the operator to 
fire his explosive charge without a long 
open time which might fog the film due to 
light leakage through the closed polar- 
izers. An image of a subject illuminated 
by direct sunlight will be dimly exposed 
in 10 sec with fast film even if the polar- 
izers are accurately crossed. 

The magnetooptic shutter described 
in this paper was the result of a redesign 
of the previously designed 4-/tsec model 
in the following ways : 

1. The aperture was reduced from 1 
in. in diameter to 1 cm. 

2. A single pair of Polaroids instead of 
two crossed pairs was used. 



286 



September 1953 Journal of the SMPTE Vol. 61 



3. The capacity was decreased from 4 
to 0.3 fjif. 

4. A spark gap and capacitor assembly 
was designed to eliminate as much cir- 
cuit inductance as possible. 

The main capacitor circuit consists of 
ten 0.03-/if capacitors in parallel, ar- 




Fig. 1. One microsecond shutter in 
square case in front of a 4 X 5 in. view 
camera. Note photoelectric cell on side of 
shutter for triggering from the light 
pulses from explosions. The box at the 
bottom includes power supplies and 
control circuits. 



ranged to have a low interconnecting 
inductance. Figure 2 shows the assem- 
bly in the casting that encloses the 
capacitors and the magnetooptic shutter 
together with the gaps and associated 
pulse transformers. 

Figure 3 shows a cross section of the 
magnetooptic shutter as well as details 
of the electrical circuit that pulses the 5- 
turn coil around the extra-dense flint- 
glass magnetooptic element. The glass 
is constructed of Bausch & Lomb Type 
EDF-4 annealed glass in the form of a 
cylinder 1 cm in diameter and 2 cm long. 
The two-gap circuit is used to excite the 
shutter coil for a half-cycle as has been 
described in the reference given above. 
These two gaps are shown in the dia- 
gram, Fig. 3, together with the pulse 
transformers that trigger them. 

The "A" pulse coil initiates the dis- 
charge of the 0.3-/zf capacitor into the 
coil around the glass element. The "B" 
pulse coil triggers the quench airgap 
which short-circuits the main capacitor 
into a damping resistor after a half-cycle 
of operation. In this manner, the energy 
in the circuit is removed so that the 
capacitance, C, and inductance, L, will 
not oscillate. 

The light-time transmission of the 
shutter under normal operating condi- 
tions is shown in Fig. 4, as sketched from 
oscillographic observations. The 100% 
light transmission refers to the trans- 
mission with the polarizers (Type HN23) 
in a parallel position which corresponds 
to a density of about 1. The transient 
open-transmission density is close to that 
of the uncrossed condition since the rota- 
tion is about 90. 

Electrical cables connect the camera 
and shutter portion to the power supply 
and control unit, which are in the box 
shown on the floor in Fig. 1 . Details of 
the delay and trigger circuits in the con- 
trol unit are given in Fig. 5. The trigger 
portion of the circuit is usually a photo- 
electric tube, marked 929 on Fig. 5, 
although a "make" circuit or a positive 
voltage pulse is equally effective. The 



Edgerton and Germeshausen: Microsecond Still Camera 



287 




Fig. 2. Inside view 
of the magnetooptic 
shutter showing 

capacitors, spark 
gaps, trigger trans- 
formers, etc. 



Fig. 3. Cross-sectional view of 
magnetooptic shutter and driv- 
ing circuit. 




0.5 1.0 

TIME IN MICROSECONDS 

Fig. 4. Transmission of the 
magnetooptic shutter as a 
function of time. 



288 



September 1953 Journal of the SMPTE Vol. 61 




- 

- 



Edgerton and Germeshausen: Microsecond Still Camera 



289 




Fig. 6. Composite photos. Below: a square stick of Pentolite -4- in. on a side and 6 in. 
long. Note fractured portion repaired with scotch tape. Above left: a 1-jusec. 
exposure with an EG&G Type 2208-0 Rapatronic camera timed 15 yusec following initia- 
tion. Note ripple in shock flame front corresponding to fracture. Also note that 
luminosity does not start at the detonation front on the stick. Above right: end view 
of a similar explosion. (Photos taken at the Ballistic Research Laboratory, Aberdeen 
Proving Ground.) 



flash of light from a subject illuminates 
the photocell creating a voltage pulse 
which trips the thyratron (VI 02) and the 
delay RC network. A dial on the unit 
controls the resistance (50 K variable) 
of the RG coupling portion of the circuit. 
The pick-off thyratron (VI 03) triggers 
after the time delay as determined by the 
pick-off voltage on the adjustable resistor 
(10K). The coil "A" exciting thyra- 
tron, VI 04, triggers instantaneously with 
VI 03 followed in about f jwsec by VI 05 
which triggers the quench gap and coil 
"B." 

Examples showing f-in. square sticks 
of pentolite as they explode are shown in 
Fig. 6. These photographs were made 
with the camera of Fig. 1 with the time 
delay set at 15 ;usec. The explosions 
were in a heavy-walled concrete chamber 
at the Terminal Ballistic Laboratory at 
Aberdeen, Md., where a thick glass win- 



dow of the shatter-proof type permitted 
the camera to be placed close to the ex- 
plosions without danger. 

An interesting and often useful effect 
results when the quenching gap is pre- 
vented from firing. One method of 
accomplishing this is to remove the 
thyratron VI 05 from its socket. If the 
quench gap does not operate, then the 
current through the shutter coil will 
oscillate at the natural frequency of the 
circuit consisting of the capacitance, C, 
and coil inductance, L, as given by 

f = 1/27T VLC cycles/sec 

The shutter does not depend upon the 
polarity of the current, therefore the 
shutter will open twice per cycle. The 
frequency is about one million times per 
second. Figure 7 shows the same sub- 
ject as Fig. 6 when photographed with an 
undamped shutter. Note the interesting 



290 



September 1953 Journal of the SMPTE Vol. 61 




Fig. 7. Below: two 3-in. sections of J-in. square Pentolite 
sticks taped together with scotch tape. Above: same subject 
photographed by EG&G Type 2208-0 Rapatronic with shutter 
oscillating 1 me. (Tube V105 has been removed so that the 
quench gap does not fire.) Note high velocity of products from 
the end of the explosion. 



end effects when the explosion reaches 
the end of the explosive. 

Teletronic Assembly 

The shutter previously described has 
been used also with two telescope types of 
mirror optical systems of long focal 
length. In this way large explosions can 
be studied photographically from a safe 
distance. 

One of the telescopes was a Wollensak 
40-in. Mirrortel. The primary image 
was formed in the magnetooptic glass 
element and subsequently enlarged twice 
on a 35mm Exakta Camera. The reflex 
features of this camera were used for 
initial alignment and focus. A "before" 
photograph was taken immediately prior 
to detonation to show size and any un- 
usual features. 



A photomultiplier tube was used to 
trigger the magnetooptic shutter for the 
distance photographs (approximately 
750ft). A tube with small holes at both 
ends was used to exclude most of the 
daylight that would saturate the tube. 

The other telescope was a Newtonian 
system of about 6-ft focal length. The 
primary image was again brought out at 
the front of the telescope by means of a 
small right-angle mirror into the mag- 
netooptic shutter. As before, the image 
was then enlarged twice on a 35mm 
Exakta Camera. 

Photographs of one of the telescope 
cameras and examples taken with it at 
the Aberdeen Proving Ground are given 
in accompanying figures. 

Often a series of accurately timed 
photographs is desired when an explosive 



Edgerton and Germeshausen: Microsecond Still Camera 



291 




Fig. 8. Wollensak Mirrortel (40-in.) mounted on a 1-jusec 
shutter with an Exakta Camera. Below is photomultiplier trigger. 



event is studied. To accomplish this, a 
series of several magnetooptic cameras 
can be used, each with a different time 
delay. A sequence of pictures like these 
can be compared to a motion-picture 
record, except that the rate may be 
irregular as set on the time-delay dials 
and the pictures can be taken with 
different lenses. Furthermore, very few 
motion-picture cameras can operate at 
cycling rates or individual exposure 
times corresponding to those obtainable 
from the magnetooptic shutter. The 
focal lengths of the lenses can be changed 
to cover the subject properly at the re- 
quired instants of time. Stereoscopic 
photographs of explosions can also be 
taken by using two cameras that have 
the same delay but with different posi- 
tions of the cameras in space. 

The 1-jusec magnetooptic shutter with 
photoelectric triggering and time-delay 
circuits provides a convenient new field 
research tool for the explosive engineer 



and scientist. Especially with long focal- 
length optics, excellent resolution of ex- 
plosions in space can be obtained at a 
safe distance and without the necessity of 
elaborate protection. Shutter syn- 
chronization by means of light from the 
explosion is most convenient since no 
electrical or mechanical connection to 
the explosion is required. 

Discussion 

Anon: Has any attempt been made to 
synchronize the optical shutter technique 
with moving film? 

Dr. Edgerton: No. 

Anon: It sounds as though it would be a 
very potent idea. 

Dr. Edgerton: Compared to the Kerr cell 
our exposure is very long. As we saw the 
other day, it is possible to get very sharp 
definition with the Kerr cell, while the 
duration of the magnetooptic shutter is 
quite a bit longer. 

Anon: One of the major advantages that a 
d-c driven motion-picture camera has to 



292 



September 1953 Journal of the SMPTE Vol. 61 




25 blocks of TNT (above) 
and (below) detonation. 



65-lb pentolite sphere (above) Cylindrical charge 
and (below) 30 /zsec after (above) and (below) 
detonation. after detonation. 



Fig. 9. Teletronic photographs taken with Wollensak 40-in. Mirrortel and l-/zsec 
shutter shown in Fig. 8, at a distance of about 750 ft (Ballistic Research Laboratory, 
Aberdeen Proving Ground). 



offer all the way along is that it permits 
higher and higher camera speeds resulting 
in shorter and shorter exposures. 

Dr. Edgerton: Well, we get shorter ex- 
posures another way. The Rapatronic 
camera is simple. The 110-v a-c power 
supply weighs only 35 Ib and the camera 
weighs less. When a picture interval in 
milliseconds is required with a total of 50 
pictures, just get 50 of these, line them up, 
set the lights, and all 50 of them will go. 
If you want 100 of them, get 100. What 
difference does it make? 

With this approach to the problem, you 
get as many pictures as you need. Every 
effort has been made to get the simple, 
reliable field tool ; not a complicated thing 
with jets, turbines and other fancy affairs. 
This 1 -isec shutter has been designed in an 
effort to get an everyday working tool, just 
like your automobile or jacknife. For ex- 
plosion engineers it seems to me it's a 
natural. Up to now there was no tool ex- 
cept slit-type cameras to measure the 
velocity, so they have been living on a one- 



dimensional world. All the data are 
merely recorded on a slit to get velocity of 
the detonation. The Rapatronic camera 
records a two-dimensional world, with an 
excellent, clear image. 

Anon: Did you take the before-and-after 
pictures through the same optics, and, if so, 
did this require moving the optical shutter 
out of the path? 

Dr. Edgerton: Yes, with the earlier model 
used at that time. It's very important to 
get a complete still picture of the subject for 
reference. We used to do it by shining 
stroboscopic light on the subject and then 
triggering the shutter. On the current 
model one simply rotates the lever and the 
optical shutter is open, permitting focus on 
a ground glass. 

In fact, you use the mechanical shutter 
just like you would in normal photography. 
The only difficulty you have is that in the 
"open" position two polarizers are parallel 
and produce a density of approximately 
one, and experience dictates the excess 
exposure required. Then you have to re- 



Edgerton and Germeshausen: Microsecond Still Camera 



293 



member, of course, to close the optical 
shutter. That is like pulling your dark 
slide ; it is very important. 

Lawrence F. Brunswick (Colorvision Inc.}'. 
Is it possible that the apparent lack of 
luminance at the point of explosion in these 
photographs is actually a result of consider- 
able over-exposure and consequent re- 
versal? 

Dr. Edgerton: Mr. Sultanoff, would you 
answer that? 

Morton Sultanoff (Aberdeen Proving Ground} : 
We have experienced this condition, and 
I would say quite positively that it is not the 
result of reversal from over-exposure. 
Much more work on this matter was pub- 
lished recently in open literature by the 
Bureau of Mines. I think this was in their 
October-December "Physics and Chemis- 
try of Explosive Phenomena" progress 
report. Their explanation is based on 
theory which predicts that a rarefaction 
wave moves in from the surface and causes 
the pressure in the detonation front near the 
surface to be reduced in bare charges. 
This makes the detonation velocity lower, 
and consequently results in a front that 
curves back at the surface. The appear- 
ance of the shock not joining the detonation 
front at the surface is explained in the 
Bureau of Mines report as the result of that 
curvature. If you are interested you 



might contact them the group under 
Dr. Bernard Lewis for more information. 

Wallace Allan (Naval Ordnance Test Sta- 
tion, Inyokern, Calif. } : Does the field of view 
of the shutter have any advantage over the 
Kerr cell? The Kerr cell is limited to a 
rather small field of view. 

Dr. Edgerton: No, these pictures are taken 
with a standard 4X5 camera with fixed 
lens. The image size on the film is about 
an inch. 

Mr. Allan: That is a fairly small angle, if 
you desire as much as 60-70. 

Dr. Edgerton: The shutter will accept 70. 
A 6|-in. lens and 4X5 plate can record a 
maximum of 50. It is the object that 
must then be big enough. 

Anon: Gould your system find applica- 
tion, perhaps, in photographing the burn- 
ing of kerosene? 

Dr. Edgerton: There are two functions of 
this shutter: One is to keep the light out 
for exposure. You might want to use one 
of these shutters to eliminate light. That is 
like the example of the firecracker that I 
showed you. The other is when you photo- 
graph the light from the explosion. Now I 
doubt whether burning kerosene has a high 
enough light level to record during this 
relatively short exposure time. This shut- 
ter is a new thing, and we are still looking 
for new uses for it. There aren't too many 
people who shoot off explosions. 



294 



September 1953 Journal of the SMPTE Vol. 61 



Benefits to Vision 
Through Stereoscopic Films 



By REUEL A. SHERMAN 



This paper emphasizes the need for good engineering in the production of 
stereo films to insure conformity with normal patterns of psycho-physiological 
functions of binocular vision. It describes the impact of stereoscopic motion 
pictures on the ophthalmic world and outlines some of the therapeutic benefits 
from viewing stereoscopic motion pictures. An orderly program is needed 
to inform the public of the potent stimulation to good binocular vision which 
results from viewing properly produced and projected stereoscopic motion 
pictures. 



J_JET us LOOK IN at a Main Street 
theater in our average American 
city. The last row of seats is 75 ft 
and the front row is 22 ft from the screen. 
John and Jane Doe have come to see the 
new stereoscopic feature. They have 
taken the average seat 50 ft from the 
screen. 

John is a skilled mechanic, an aver- 
age American citizen, 35 years of age, 
in good health. He has good vision, 
eyes that are skillful. They function 
smoothly, effortlessly and instantly. 
The glasses he wears help to give him 
this efficiency. 

Jane is the same age, and a good 
housewife. She wears no glasses. She 
has been told by her doctor that she 



Presented on April 27, 1953, at the So- 
ciety's Convention at Los Angeles by 
Reuel A. Sherman, Bausch & Lomb 
Optical Co., Rochester 2, N.Y. ; previously 
published in part in the Bausch & Lomb 
Magazine, vol. 29, No. 1. 
(This paper was received April 19, 1953.) 



should wear a prescription but she 
doesn't. Her trouble is not in her 
ability to see clearly because her acuity 
in each eye is excellent, but for other 
reasons she is visually uncomfortable. 

The feature starts. John and Jane 
put on their polarizing spectacles and 
settle back comfortably for an evening 
of thrilling entertainment. Before the 
show is over, John is having trouble. 
His ordinarily skillful, efficient, binocular 
vision is causing him obvious discom- 
fort. On the other hand, Jane who 
usually experiences difficulty is enjoying 
the performance with greater freedom 
from symptoms of visual disturbance than 
she ordinarily has in her daily occupa- 
tions. 

The cause of this apparent incongruity 
is in the vertical displacement of the two 
images. By not keeping the two images 
in frame, the projectionist has put an 
unnecessary burden on 98% of the 
patrons in the theater. By so doing he 



September 1953 Journal of the SMPTE Vol. 61 



295 



has made it easier for the remaining 
2% including Jane. The screen image 
from the right-eye projector is not framed 
vertically with the screen image from 
the left-eye projector. Jane has a right 
hyperphoria. The visual axis of her 
right eye tends to be above that of her 
left eye. The improperly projected 
picture automatically compensates for 
her visual impediment. 

On the other hand, the 2% of the 
patrons in the theater who have a 
left hyperphoria are penalized even more 
than John who represents the 96% with 
correct vertical phorias. 

John's eyes were not harmed even 
though he experienced discomfort from 
the abnormal visual gymnastics which 
they performed in maintaining fusion 
of the improperly aligned frames. No 
physiological damage could have re- 
sulted. Nevertheless the discomfort was 
unwarranted. 

Vertical alignment of the frames and 
synchronization of the two projected pictures 
must be exact. Had the right-eye and 
left-eye frames been precisely and cor- 
rectly aligned, Jane probably would have 
had considerable discomfort while 96% 
of the customers, including John whose 
eyes were in normal balance vertically, 
would have been comfortable and happy. 
This would have re-emphasized to Jane 
her need for professional, ophthalmic 
services for her own general well- 
being both in and out of the theater. 
The stereoscopic pictures could have 
been the stimulus needed for her to put 
her visual house in order. 

The illumination from the two projectors 
should be matched as equally as possible. If 
relative illumination between right- and 
left-eye images varies more than 12%, 
some individuals may find that interfer- 
ence with their binocular vision results. 

A small number, approximately 2% 
of the population, have better and more 
efficient binocular vision when the right- 
eye visual image is more luminous than 



the left-eye visual image. Another 2% 
have more efficient binocular vision when 
the left-eye image is more luminous than 
the right-eye image. 

Slight differences between the visi- 
bility of right- and left-eye stereoscopic 
pictures do not seem to bother the aver- 
age individual. But when the 2% whose 
eyes perform better with less luminosity 
in the right eye get more of it by un- 
equally balanced illumination in the 
projectors, the tendency is to aggravate a 
latent condition which interferes with 
binocular efficiency. 1 ' 2 - 3 

The projection lenses should be matched. 
It is recommended that variances between the 
right- and left-eye lenses do not exceed plus 
or minus 0.5% in focal length. For an- 
other example, let us consider a second 
couple sitting in the Main Street theater 
at a distance of 50 ft from the screen. 
He has excellent visual acuity in each 
eye, good binocular functional ability, 
while she has difficulty with any visual 
task that requires or induces sustained 
visual concentration such as an auto- 
mobile trip, watching television, attend- 
ing the conventional movies, or sitting 
through a lecture or sermon. 

Again, viewing the stereoscopic mo- 
tion picture brings comfort and satis- 
faction to her, while to him it brings a 
visual disturbance. Again the pro- 
jectionist in this particular theater has 
something wrong with his equipment. 
The projection lenses are not matched. 
The right eye projected image is larger 
than the left eye projected image. In 
her case there was a disparity in the size 
of her retinal images which has not been 
corrected through ophthalmic care. 
The improperly matched projection 
lenses favored her condition so that she 
experienced a false sense of comfort 
while he who was not accustomed to 
disparity in size of images was irritated. 
This failure to match the lenses had 
benefited 1% of the audience and penal- 
ized 99%. 

It seems that we have picked on the 



296 



September 1953 Journal of the SMPTE Vol. 61 




The focus mechanism of a normal pair of eyes is 
relaxed and the visual axes are practically parallel 
when viewing objects at Ions distances. 




When looking at a near point, the 
focusing mechanism accommodates 
and the visual axes converge at 
the point of regard. 

Figure 1 



2 /3 of convergence 

is stimulated 

through accommodation. 

It is referred 

to as accommodative 

convergence. 

!/3 of convergence is 
stimulated by desire 
to fuse right and left 
eye images. It is referred 
to as fusional 
convergence. 



projectionist in the Main Street theater 
as having committed mechanical errors. 
Surely we can conceive of no combina- 
tion of all such circumstances happening 
in any one theater during the exhibition 
of any one feature. Nevertheless, one 
of them can easily happen if conditions 
are not checked carefully. 

The penalizing of producers, theater 
owners and the public through lack of 
attention to these details is unfortunate. 
A small percentage of patrons with visual 
difficulties will be favored by such errors, 
while the majority with normal binocular 
vision will be disturbed. These condi- 
tions should be reversed so that those 
with normal binocular vision will be 
stimulated to even greater enjoyment of 
the feature, while those who should do 
something about their visual perform- 
ance will receive the incentive to act 
in their own behalf. 

Of the customers who view stereo- 
scopic motion pictures 85 to 88% can 



enjoy them without feeling visual tension 
or discomfort, providing consideration 
is given to those projection problems 
which we have covered, and providing 
the films are properly produced. The 
relationship between two visual functions, 
accommodation (focus) and convergence, 
probably is one of the important factors 
to consider in the production process. 
An understanding of the inter-relation- 
ship between these two visual functions 
may help in outlining certain rules. 
The accommodative-convergence rela- 
tionship in a pair of human eyes will 
be considered only as it relates to the 
production of stereoscopic pictures and 
as the viewing of the pictures influences 
these functions. 

Figure 1 illustrates the relationship 
between the focusing of a pair of eyes 
and their converging toward and on the 
point of regard. As the normal pair of 
eyes changes fixation from a "long shot" 
to a "close-up," or from a far point to 



Sherman: Vision Benefits Through Stereo 



297 



a near point, two demands must be met 
to obtain single, clear binocular vision: 

1 . The focusing action of the eyes must 
adjust so that a sharp image will appear 
on each retina. 

2. The 12 extra-ocular muscles must 
coordinate to turn each eye so that it 
will look precisely at the object of regard. 

To a large extent binocular seeing is a 
learned function. 19 Some of us learn to 
see with skill and efficiency; others do 
it clumsily, haltingly, and inaccurately. 
In the average individual these complex 
adjustments are made instantly and with 
effortless facility. Through the condi- 
tioning of reflexes or other psycho- 
physiological functions, a stimulation to 
convergence induces accommodation and 
inversely a stimulation to accommoda- 
tion induces convergence. 

Two-thirds of the amount of conver- 
gence required for fixation ordinarily is 
induced by the effort to accommodate. 
In Fig. 1 the shaded area represents this 
amount, which usually is referred to as 
accommodative convergence. The re- 
maining third usually is referred to as 
fusional convergence. Fusional conver- 
gence is a reflex action induced by the 
mental desire for a single image. It is 
achieved by the eyes turning so that the 
image of regard is on corresponding 
points of each retina. Most of us with 
binocular vision demonstrate varying 
degrees of this accommodative conver- 
gence relationship with the great major- 
ity grouped around the limits indicated 
by this figure. 21 

We have emphasized the importance 
of accommodation in stimulating con- 
vergence but conversely the effort to 
converge also stimulates accommodation. 
This accommodation convergence which 
works both ways has been established 
through habit and learning. Those of 
us with effortless, skillful binocular co- 
ordination will converge when a stimulus 
is applied and still maintain our accom- 
modation at the point where it is re- 
quired for sharp focus. Others have 
little latitude between their accommo- 



dation and convergence. They have 
what might be referred to as a "tight 
hook-up" between the two functions. 
They cannot relax one function easily 
while stimulation of the other is main- 
tained. 

Such individuals usually have the 
ingredients for very efficient seeing, 
but interfering reflexes in their accommo- 
dative-convergence habits cause func- 
tional opposition often associated with 
discomfort. Their convergence may be 
overstimulated by their accommodation. 
In other cases there is little or no inter- 
functional stimulation. Their accom- 
modative effort does not induce con- 
vergence, nor does their convergence 
effort induce accommodation. 

These abnormal situations are prob- 
lems for the skilled ophthalmic practi- 
tioner. The accommodative-conver- 
gence relationship, however, has an 
engineering connotation in the produc- 
tion and projection of stereoscopic 
motion pictures. 

More often than not, those who lack 
flexibility between the functions of 
accommodation and convergence have 
excellent acuity with each eye. Judging 
their visual abilities solely by the sharp- 
ness of their sight, such individuals are 
lulled into a false sense of security 
into a feeling that such excellent acuity 
precludes any need for professional serv- 
ices. Such subjects probably will be 
identified as needing professional at- 
tention by discomfort resulting from their 
viewing of stereoscopic motion pictures. 

Figure 2 illustrates the impact of 
viewing stereoscopic motion pictures on 
the accommodative-convergence func- 
tions. It also illustrates the impor- 
tance of considering these factors in 
producing films. In binocular perform- 
ance, our accommodation gives us 
our sharp clear images by which we 
identify the object of regard; whereas 
convergence enables the two eyes to 
fixate or center upon the object of re- 
gard, so that single vision is maintained. 
In stereoscopic motion pictures our ac- 



298 



September 1953 Journal of the SMPTE Vol. 61 



Left 




Uncrossed disparity on 
Long Shots or Far Points 



here 




Crossed disparity on 
"Close lips" or "Near Points 
Figure 2 



Ri 9 ht eye 



Right eye image 



Left 



eye image 



commodation gives us our sharp clear 
images. Our convergence localizes the 
objects in space either in front of or 
behind the screen (stereo windows). 
Efficient and effortless viewing demands 
new and independent responses from the 
two functions. Accommodation (or 
focus) must be maintained constantly 
on the surface of the screen if the in- 
dividual is to see a sharp image. Con- 
vergence must act with independent flexi- 
bility so that each eye will point to its 
own image without the aid of accommo- 
dation, or conversely without inter- 
fering with the maintenance of it on the 
surface of the screen (stereo window). 

In other words, those people who con- 
verge skillfully, independently of their 
focus, get a stimulating calisthenic ex- 
perience from viewing properly made 
stereoscopic motion pictures. Such 
practice teaches them to converge when 
the stimulus to convergence is presented 
and to accommodate when the stimulus 
to accommodation is presented. View- 
ing stereoscopic pictures provides an 
excellent exercise in developing flexi- 



bility between the two functions and 
precision in each one. Fortunately 
such individuals are by far in the major- 
ity. On the other hand, those who 
have a "tight hook-up" between their 
accommodation and convergence should 
profit greatly from ophthalmic attention 
and from the visual "setting up exer- 
cises" provided by the same pictures. 

The optometrist or ophthalmologist 
whose help is sought as a result of dis- 
comfort experienced from viewing prop- 
erly made stereoscopic motion pictures 
will make careful tests of the refractive 
condition of each eye, and of the func- 
tional pattern of seeing. His prescrip- 
tion may include simple or complex pre- 
scription lenses different for each eye, 
specifically designed for the condition of 
the individual. Such lenses may serve 
several very useful purposes. They may 
balance the acuity of the two eyes. 
They may also stabilize the accommo- 
dative-convergence relationship. 

In addition, the professional man may 
prescribe a series of training procedures 
to teach each eye to function efficiently 



Sherman: Vision Benefits Through Stereo 



299 



rf 




SCREEN 



Foresround 
Disparity 



Figure 3 



by itself. When this is accomplished 
he may then continue the training so as 
to teach the two eyes to function together 
effortlessly and skillfully. A part of this 
training procedure may well be the recom- 
mendation to see stereoscopic motion 
pictures periodically once a day or 
once a week for example. It may be 
that he will recommend to his patient 
that he choose a seat in the front row 
for the first day and, as he improves in 
visual performance, that he move pro- 
gressively back a row or two of seats, so 
that eventually he can sit in the rear row 
and view the full feature with comfort 
and satisfaction. For other patients he 
may reverse the prescription, suggesting 
that they start in the back row and 
periodically move closer to the screen. 

The disparity of the projected images of 
close-ups should not exceed 1/20 of the dis- 
tance between the screen and the closest 
spectators. For example it should not ex- 
ceed 72 in. in theaters where patrons will be as 
close as 20 ft from the screen. A fore- 
ground (crossed) disparity of 12 in., 
viewed from a distance of 20 ft will 
mean that the individual will need to 
converge as though looking a I a point 
approximately 4 ft in front of him while 
still maintaining his focus on the surface 
of the screen 20 ft away. 20 The average 
person will be able to do this with ease 
provided such stimulation is momentary 
and infrequent. It would be difficult for 



most of us to maintain this convergence 
over a long period of time. 

The close-up disparity can be increased 
or decreased in direct ratio to the distance 
of the nearest seats to the screen. As a 
further example, if the nearest point of 
observation from the screen is to be 30 
ft, the foreground disparity can be as 
high as 18 in. and still remain within the 
range of tolerance of the average indi- 
vidual. 

The background (uncrossed} disparity 
should not be more than 2^ in. in pictures 
produced for entertainment. This holds 
true regardless of the size of the screen 
or of the distance from the screen to the 
audience. As the distance increases, 
however, the objectionable reactions of 
some individuals will be less, but the 
undesirable situation will still be there. 

Consideration should be given to the 
various sizes of screens upon which stereo- 
scopic motion pictures will be projected. 
The producer considers this variance in 
screen sizes in preparing the films for 
distribution. 

Figure 3 shows the convergence re- 
quired of three individuals sitting in a 
theater viewing a stereoscopic picture 
with a close-up (crossed) disparity of 6 
in. "A" sitting 75 ft from the screen, 
"B" 50 ft from the screen, and "C" 25 
ft from the screen. The 6-in. foreground 
disparity will cause A, B and C each to 
see the object of regard at the point where 



300 



September 1953 Journal of the SMPTE Vol. 61 




Unequal focus often is a cause 

of binocular disturbances. 

Figure 4 



SCREEN 



the visual axes of each cross. C must 
converge over three times as much as A 
to fuse the two pictures. 

Figure 4 illustrates the effect of back- 
ground disparities on the accomoda- 
tive-convergence relationship. Accom- 
modation must be maintained on the 
surface of the screen while convergence 
relaxes. If the background disparities 
are greater than the interpupillary dis- 
tances of the theater customers then an 
unnatural demand for divergence is 
made upon them. Such a demand is 
undesirable for the average individual. 

Out of focus or "soft focus" photography 
should be avoided in all stereoscopic work. 
All details on the screen must be sharp and 
clear to avoid disturbances to the accommo- 
dative-convergence associations of the audience. 

Let us take another example of a 
customer sitting in the middle of the 
theater 50 ft from the screen. This man 
has never had a professional eye examina- 
tion. He has gone blithely along under 
the assumption that his vision was effi- 
cient because he was comfortable. The 
facts of the case are that his two eyes do 
not focus at the same plane. While one 
of them is looking at the screen, the 
other theoretically will be out of focus. 
In ordinarily occupations this person has 
learned to suppress mentally the vision 
of, say, his right eye. Had he not 
learned to do this at an early age he 



surely would have been uncomfortable 
because the images of the two eyes were 
not compatible. Confusion as well as 
discomfort would have resulted. 

He puts on his polarizing spectacles. 
The powerful stimulus of a large stereo- 
scopic picture with motion, sound and 
color, suddenly hits him. His habitually 
suppressing eye cannot ignore it. Con- 
fusion in his seeing, with resulting dis- 
comfort, begins to plague him. Surely 
he should not blame the producer, the 
exhibitor or the stereoscopic system. 
He is in need of visual attention, and the 
stereoscopic motion pictures should re- 
ceive credit for identifying this need. 
Previously he was comfortable but in- 
efficient in some of his visual skills. 

The chances are nine to one in his 
favor that a visit to an ophthalmic 
practitioner will bring many benefits to 
him. After proper lenses have been 
fitted, one of these benefits should be 
the ability to view three-dimensional 
films with comfort and full appreciation 
of true stereoscopic seeing. The doctor 
may wish to prescribe frequent attend- 
ance at stereo features so that the two 
eyes will be further stimulated to work 
together as a team. 

Stereoscopic motion pictures will brini 
to the public many benefits which go 
far beyond the enteriuinmrni farior. 
For example, facts gathered over the p.tsi 
14 years of extensive research at Purdue 



Sherman: Vision Benefits Through Stereo 



301 



University under the direction of Joseph 
Tiffin, have demonstrated that our binoc- 
ular seeing performance is related 
directly to out occupational perfor- 
mance. 11 Some of these relationships 
are: 

1. Freedom from accidents. 4 - 5 

2. Productiveness. 6 - 7 ' 8 ' 17 

3. Freedom from discomfort on visual 
tasks. 7 . 8 * 17 

4. Accuracy in assembly, inspection 
and other fine work. 9 - 10 - 17 

5. Like, or dislike, of certain activi- 
ties. 8 . 16 ' 17 

Seeing is something we do. It doesn't 
just happen to us. It is a complex act 
and not a unitary function such as the 
ability to see clearly with each eye at a 
distance. Some of us see skillfully and 
well. Others do it clumsily and in- 
efficiently. Some of us do it effortlessly 
while others do it with apparent diffi- 
culty and discomfort. 18 

Furthermore, seeing is different from 
other measurable human character- 
istics such as finger dexterity, tempera- 
ment, motivation, intelligence or height 
and weight. Something can be done to 
improve it when it is below desirable 
standards. The ophthalmic practitioner 
can, in a high percentage of cases, 
transform inefficient, clumsy or uncom- 
fortable visual performance into smoothly 
performing, effortless and skillful seeing. 
With the advent of stereoscopic motion 
pictures he will find facilities which 
will help him with many of these cases. 

Fortunately for the segments of the 
motion-picture industry concerned with 
stereoscopic productions, the trend to- 
ward the diagnosis and treatment of 
binocular imbalances has proceeded at a 
very rapid rate during the past two dec- 
ades. The benefits are not one-sided. 
Those pioneers in the ophthalmic field 
who long have recognized the importance 
of efficient binocular vision will now have 
a powerful ally to help focus attention on 
stereoscopic seeing. The public will 
be the beneficiary from this added at- 
tention to its visual needs. 



This is the age of vision. It is the 
age of speed and precision. The work 
load has been lifted from men's backs 
and placed on their eyes. In our fac- 
tories, offices and schools, and on our 
highways, the need is for visual skill 
and for judgment based on visual per- 
ceptions. We read gauges, make ad- 
justments of delicate instruments, in- 
spect through microscopes, move levers 
which guide rapidly moving machines. 
The task of reading reports and prepar- 
ing blue prints is never done. The com- 
mon laborer who can rely on casual 
vision is becoming rare. The farmer 
can no longer plod wearily behind the 
plow. He drives machines, keeps books. 
This is the age of TV and 3D. 

The ophthalmic professions and the 
ophthalmic industry have met the chal- 
lenge. As an example, Bausch & Lomb 
Optical Co. initiated research in the 
field of vision as it relates to our occupa- 
tions, and established a research grant at 
Purdue University. The ophthalmic 
professions gave active support. 15 Man- 
agements of many of our leading indus- 
trial and commercial companies co- 
operated by testing the visual perform- 
ance of thousands of employees on a 
large variety of jobs. They assembled 
measures of employee success, such as 
accident experience, records on absen- 
teeism, hospital visits, tenure on the 
job, earnings, quality and quantity of 
work. 13 . 14 The statistical analysis of 
these data provided factual evidence to 
establish : 

1. That stereoscopic testing instru- 
ments are necessary to provide an ac- 
curate profile of an individual's binocular 
performan ce . 12 

2. That stereoscopic factors of vision 
are important in our everyday occupa- 
tions. 13 - 14 

3. That giving consideration to each 
eye independently, without also giving 
equal attention to how the two eyes 
perform as a team, can be unfair to the 
individual. 11 



302 



September 1953 Journal of the SMPTE Vol. 61 




Fig. 5. The Ortho-Rater: a stereoscopic instrument for testing visual skills. 



The visual testing instrument that 
resulted from these extensive investiga- 
tions was the Ortho-Rater (Fig. 5). It 
provides highly reliable tests of 12 of 
the most important visual skills. 12 

Instruments of this type are used 
widely in industrial and commercial 
companies, in the military forces, and 
other areas. When one thinks of the 
motion-picture industry, the question 
might well be asked, "Do all of the indi- 
viduals concerned with the production 
and projection of stereoscopic films 
possess the visual qualifications which 
will permit them to handle the job most 
efficiently?" Tests such as are contained 
in the Ortho-Rater might provide re- 
vealing information. 

It is conceivable that the use of an 
instrument of this type will enable one 
to predict the probabilities of an indi- 
vidual's sitting through a 90-min stereo- 
scopic feature without apparent visual 
discomfort. On the assumption that 



such a visual standard could be estab- 
lished, we could then say that those who 
meet the standard could probably view 
the stereoscopic pictures without dis- 
comfort or effort, and that those who 
fail the standard should seek professional 
eye care for the sake of their own health 
and general well-being, even though 
they are not planning to view stereo- 
scopic motion pictures. We also could 
tell them that, according to the laws of 
probability the chances are nine to one 
that they would be benefited by pro- 
fessional eye care. In addition, a small 
but very important percentage of those 
who fail to meet the standard, and who 
consult a professional man, will dis- 
cover that the cause of their low visual 
performance is a pathological difficulty 
not originating in the eyes even though 
it reflects in impaired visual functioning. 
During the period between 1850 and 
1870, Dr. Oliver Wendell Holmes did 
much to popularize the stereoscope which 



Sherman: Vision Benefits Through Stereo 



303 




Fig. 6. The Holmes model of the 
Brewster Stereoscope. 

bears his name (Fig. 6). This instru- 
ment occupied a prominent place on 
the parlor table of every cultured home 
at the turn of the century. In the At- 
lantic Monthly of 1859 Dr. Holmes wrote, 
"The Stereograph is to be the card of 
introduction to make all mankind ac- 
quainted." In response to this statement 
of nearly 100 years ago, some have smiled 
and said that Dr. Holmes did not fore- 
see the impact of rotogravure, motion 
pictures, radio and television. Others 



today can smile and say that his prophecy 
is being fulfilled now that the stereo- 
scope has come to motion pictures, and 
in the future* may come to television. 

Dr. Holmes saw the educational value 
of the stereoscope but he did not fore- 
see it as a therapeutic instrument. 
Javal first used the stereoscope for the 
treatment of crossed eyes (squint) as 
as early as 1895. 22 Since that time it 
has been the accepted means for visual 
training (orthoptics) . In fact, some 
form of the stereoscope is the only means 
known for developing good binocular 
habits in those individuals who have the 
basic ingredients for normal two-eyed 
seeing but who have not learned to use 
them efficiently. 

Motion pictures greatly extend the 
use of the stereoscope in this important 
field. They remove one of the restrain- 
ing barriers that have limited visual 




Fig. 7. An Ortho-Fuser in use. The kit contains 5 vectograms of stereoscopic design, 
bound with instruction sheets in booklet form, and a pair of polarized spectacles. 



304 



September 1953 Journal of the SMPTE Vol. 61 



training. Previously the monotony of 
the treatment and lack of interest on 
the part of the patient in viewing dia- 
grams and charts in a stereoscope 
challenged the ingenuity, resourceful- 
ness and patience of the practitioners 
and technicians. Now for the first 
time thrilling drama, with color and 
stereoscopic effect combined, can be used 
as a valuable supplement to the specific, 
controlled, clinical procedures in the 
professional office. 

In view of the widespread use of stereo- 
scopic testing and training instruments 
today, and in view of the imminent 
wide-spread use of stereoscopic motion 
pictures, we believe we can paraphrase 
Dr. Holmes' prophecy and state, "The 
stereoscope will be the card of intro- 
duction to make those who need visual 
attention acquainted with the ophthal- 
mic professions." 

When one considers the superb enter- 
tainment, educational, cultural and 
therapeutic values of properly produced, 
properly projected and properly viewed 
stereoscopic motion pictures, he can 
justifiably ask, "why should not every 
school child have the opportunity of 
viewing them periodically?" The 
powerful stimulus to better binocular 
vision will in this way be brought to the 
child during the formative years, while 
he is developing the pattern of seeing 
habits that may stay with him through 
life. Our first consideration, however, 
is to be sure that his eyes are right. The 
nation-wide showing of stereoscopic 
motion pictures will help to create the 
desirable awareness of the need for more 
attention to our children's vision. In 
consequence it will hasten the day when 
we can be sure that their vision is ade- 
quate for their various activities. 

The educational job must not be a 
publicity program. It must be an 
orderly and constructive procedure that 
will earn the cooperation of the many 
strong allies who also are keenly inter- 
ested in the success of the motion-picture 
field's program. 



References 

1. H. Grimsdale, "A note on Pulfrich's 
Phenomenon with a suggestion on its 
possible clinical importance," Brit. J. 
Ophthalm., 9: 63-65, 1925. 

2. R. M. Hall, "Pulfrich's Phenomenon," 
Am. J. Optom., 15: 2; 42-46, Feb. 
1938. 

3. F. H. Verhoeff, "Effect on stereopsis 
produced by disparate retinal images 
of different luminosities," Arch. 
Ophthalm., 70: 640-645, Nov. 1933. 

4. N. F. Stump, "A statistical study of 
visual functions and industrial safety," 
J. Appl. Psych., 29: 6; 467-470, Dec. 
1945. 

5. N. C. Kephart and Joseph Tiffin, 
"Vision and accident experience," 
National Safety News, 62: 90-91, Oct. 
1950. 

6. A. K. Peterson and Frank Noetling, 
"Preliminary report of progress of the 
eye programs at R. R. Donnelley & 
Sons," Trans. Am. Acad. Ophthalm. and 
Otolaryng.: 270-275, Jan.-Feb. 1950. 

7. E. W. Howard, "Fulton study relates 
vision and efficiency," Textile World, 
99: 97-99, July 1949. 

8. G. W. Morgan and N. F. Stump, 
"Benefits from professional eye care 
for workers with lowered visual per- 
formance," Trans. Am. Acad. Ophthalm. 
and Otolaryng.: 99-105, Sept.-Oct. 
1949. 

9. Leon D. Gruberg, "Effects of a vision 
program in a TV plant," Opt. J. and 
Rev. Optom., 89: 36-37, Feb. 1952. 

10. E. J. McCormick, "An analysis of 
visual requirements in industry," J. 
Appl. Psych., 34: 1 ; 54-61, Feb. 1950. 

11. H. S. Kuhn, Eyes and Industry, 2d ed., 
The C. V. Mosby Co., St. Louis, 
1950, pp. 53-71, 97, 108, 110, 145. 

12. F. W. Jobe, "Instrumentation for the 
Bausch & Lomb Industrial Vision 
Service," Bausch <2f Lomb Magazine, 
20: 1; 6-7, Feb. 1944. 

13. Joseph Tiffin, Industrial Psychology, 3d 
ed., Prentice Hall, New York, 1952, 
pp. 194-241. 

14. C. H. Lawshe, Jr., Principles of 
Personnel Testing, McGraw-Hill, New 
York, 1948, pp. 96-122. 

15. R. A. Sherman, "Ophthalmic science 
and practice applied to vision in 



Sherman: Vision Benefits Through Stereo 



305 



industry," Bausch & Lomb Magazine, 
20: 1; 1-9, Feb. 1944. 

16. N. G. Kephart, "Visual skills and labor 
turnover," J. Appl. Psych., 32: 51-55, 
Feb. 1948. 

17. J. H. Goleman and Richard Feinberg, 
"Vision tests for inspectors insure good 
placement," Factory Management and 
Maintenance, 103: 106-110, Jan. 1945. 

18. G. F. Shepard, "Visual skills," Opto- 
metric Weekly, 34: 1465-1466, Jan. 
1944. 

19. Julia E. Lancaster, A Manual of 
Orthoptics, Charles G Thomas, Spring- 
field, 111., 1951; The Sight Saving Rev. 
of the National Society for the Prevention 
of Blindness, 22: 125-126, 1952. 

20. J. A. Norling, "The stereoscopic art 
a reprint," Jour. SMPTE, 60: 268-308, 
Mar. 1953. 

21. E. F. Tait, "Accommodative con- 
vergence," Am. J. Ophthalm., 34: 
1093-1107, Aug. 1951. 

22. James E. Lebensohn, "Louis Emile 
Javal, a centenary tribute," Arch. 
Ophthalm., 21: 650-658, Apr. 1939. 

Discussion 

Lt. Col Robert V. Berrder (U.S. Air Force, 
Wright Air Development Center, Dayton, Ohio}: 
Since, when we are looking at physical 
objects at say 10 ft, objects further in the 
distance appear relatively in focus, is it not 
true that we could have convergence up to a 
point 10 ft from our position in the theater 
and still be relatively focused for image 
matter on the screen without discomfort? 

Mr. Sherman: Yes, if you mean that the 
camera can be as close as 10 ft; was that 
your point? 

Lt. Col. Bernier: No, Sir, I mean if the 
displacement of images for the crossover, as 
you mentioned, was such that the converg- 
ence occurred at 10 ft from your viewpoint, 
as you're sitting in the theater, would not 
the subject matter or the image on the 
screen be in relatively good focus even 
though we were converged and accommo- 
dated for that 10-ft position? When we 
look at physical things in real life, 10 ft 
away, objects in the medium and far dis- 
tance up to infinity appear relatively in 
good focus. 

Mr. Sherman: Yes, I get your point. 
When you look at an object suppose I 
look at Dr. Frayne, 10 ft away. I have to 



accommodate to see him sharply. I need 
to converge. I need to do both. Now, if 
I converged on Dr. Frayne and focused on 
the wall over there, which I am doing now, 
he's very blurred. Or if I converge on the 
wall and focus on Mr. Frayne, I see two of 
him. Is that bad? 

Lt. Col. Bernier: No, I didn't mean that. 
I mean to imply that this thing of optical 
infinity, you consider what? 20 ft? 

Mr. Sherman: Let's say 20 ft. 26 ft 
rather. 

Lt. Col. Bernier: That means that for 
objects in physical life beyond 20 ft, every- 
thing as far as the individual is concerned is 
in focus regardless of where you are con- 
verged. Isn't that true? Then that would 
imply that in three-dimensional motion pic- 
tures you could have objects appearing as 
close as 20 ft from your position in the 
theater and still be in focus for the image 
which is on the screen. 

Mr. Sherman: Yes. I think I get your 
point. The only difference is that I change 
both my accommodation and my converg- 
ence when I change fixation from a dis- 
tance to him. However, if I were looking 
at a projected stereo picture taken of him 
with the camera placed where I am stand- 
ing, my accommodation would need to be 
on the surface of the screen while my con- 
vergence is directed toward the picture in 
front of the screen. This would not be an 
undesirable situation and should cause no 
discomfort. 

Charles Smith (Stereo Techniques, Ltd.): 
Dr. Sherman listed among his requirements 
for properly projected and properly pro- 
duced pictures that on background objects 
the displacement of the two image points 
should not be greater than 2 in., which 
causes the eyes to squint outwards. Now, 
as we know, on some of the pictures that 
we've seen this limit of 2\ in. is very greatly 
exceeded on background objects, with un- 
pleasant results. I'd like Dr. Sherman to 
tell us whether he considers that in this 
case the results are actually harmful to the 
eyes, or merely unpleasant. 

Mr. Sherman: They are only unpleasant. 
The eyes are not hurt by diverging. The 
physical eye cannot be hurt by viewing 
stereoscopic motion pictures providing 
there is no pathology that requires absti- 
nence from normal seeing tasks. Discom- 
fort is all that might be induced. 



306 



September 1953 Journal of the SMPTE Vol. 61 



Edward Stanko (RCA Service Company, 
Camden, N.J.): Isn't it possible to overdo 
the stereoscopic effect? Recently I noticed 
that in some of the 3-D pictures they'll have 
a tree or some other object very close to the 
camera, then there will be a set 1 5 or 20 ft 
away, and then further back there will be a 
background scene. Now that's a consider- 
able distance for the eye to cover. Do you 
think that sustained photography under 
such conditions might produce eyestrain? 

Mr. Sherman: Yes, it might cause a little 
discomfort and particularly with those 
individuals who do not have adequate 
flexibility between the functions of accom- 
modation and convergence. 

Mr. Stanko: In regard to your suggestion 
that stereoscopic pictures are beneficial to 
the eye, I've had some personal experience 
with my own son. When he was a small 
boy he had one crossed eye. By using 
these stereoscopic pictures and eye exer- 
cises he was able to improve his vision con- 
siderably. 

Mr. Sherman: Well, that's interesting. 
We should keep in mind that flexibility in 
visual functions can be developed through 
some of the stereo pictures which at first 
might cause some discomfort. 

Nie Archer (Univ. of California Student}: 
Do you consider the Viewmaster Stereo 
Viewer to be of an optical quality to be 
beneficial to small children? 

Mr. Sherman: Those I have seen have 
been excellent. 

Lawrence Brunswick (Colorvision Inc.}: 
Following up Mr. Stanko's mention of the 
sets with the very great depth, I think that 
brings out the aspect that so much of our 
stereo work is done with too great an inter- 
pupillary distance between the two lenses, 
and that causes that great disparity. 
That has to be carefully watched, I believe. 
Mr. Sherman: That's one of the points of 
properly produced stereo pictures that we 
have stressed in this paper. Yes, desirable 
interaxial distances in the stereo camera are 
an essential ingredient. 

Dr. Feinberg (Northern Illinois College of 
Optometry): I wish you would amplify a 
comment you made about vertical imbal- 
ance or the effects induced by improper 
displacement vertically by the projection- 
ist. 

Mr. Sherman: There are 2% of us in this 
room, if we're average individuals, and I 
assume we are, whose right eyes tend to tilt 



upward; another 2% whose left eyes tend 
to tilt upward. If for example, the left-eye 
frame is higher on the screen than the right- 
eye frame, the 2% of us in this room whose 
left eye tends to tilt upward would have 
their condition eased while the 2% whose 
right eye tends to tilt upwards plus the 96% 
whose two eyes are in normal vertical bal- 
ance would be penalized. I have a friend 
with a Stereo Realist camera and a 3D 
Stereo Projector. He has a right vertical 
imbalance and when we visit him he tries 
to project his pictures with the right-eye 
frame slightly higher because he sees them 
comfortably that way. For the sake of the 
96% of the people who have normal verti- 
cal balance, let's keep the frames in syn- 
chronization in vertical alignment. Then 
the identifying finger is going to be on the 
4% that ought to see some of these eminent 
professional men who are here this after- 
noon. Otherwise the other 96% are likely 
to go. 

Mr. Stanko: Mr. Sherman, could you 
give a brief explanation of why a stereo- 
scopic picture appears to be smaller the 
minute that you add depth to it? I've 
noticed that the large screens that were 
used in theaters, which apparently seem to 
be large for 2-D pictures, but the minute 
that you put a 3D picture on it, it shrinks 
right down and comes right to you and gets 
smaller. Can you give a brief and simple 
explanation of that? 

Mr. Sherman: Very briefly, this phenom- 
enon is in the field of our psychological 
factors of vision. We converge on an ob- 
ject when it is near to us. Interpretatively 
we think of it as being nearby and at the 
point where our visual axes cross. It's in 
the mind, strictly, and it's related to our 
convergence interpretations. The factors 
of convergence and accommodation con- 
trol the suggestion of relative sizes. 

John G. Frayne (Westrex Corp. and Chair- 
man of the Session) : I think that that question 
will be answered in more detail tomorrow 
afternoon in the paper by Dr. Hill of the 
Research Council. 

Mr. Sherman: Dr. Frayne, may I make 
one other comment. Were we to get into 
the clinical aspect of visual performance 
and of how we see, I'm not the one who 
should answer that. Rather it should be 
the men in clinical practice who are in the 
audience. When it comes to the relation- 
ship between how we see, and how we per- 



Sherman: Vision Benefits Through Stereo 



307 



form at occupations we will try to answer 
questions. 

Winton C. Hock {Cinerama Productions): 
How much convergence disparity can your 
80% of well-adjusted people accommodate? 

Mr. Sherman: In a well-conducted clinical 
study of around 4,800 cases, Dr. Tait 
plotted the latitude between accommoda- 
tion and convergence. It ranged all the 
way from zero people who seem to have 
no latitude, at one extreme, to the other ex- 
treme where there was a very high latitude. 
In other words, with some individuals the 
stimulation to one function does not affect 
the other. But the average latitude is 
about 8 prism diopters. Now the recom- 
mendation that we made this afternoon that 
the crossed disparity or near-point dis- 
parity should not exceed 1/20 of the 
distance from the nearest spectator to the 
screen, requires only about 4| prism diop- 
ters of latitude as we refer to it. So the 



limits I have indicated still leave an ample 
latitude between what 80% of the people 
have and the limits I indicated. 

Mr. Hoch: Could you restate that in 
terms of an illustration? If a person were 
sitting in the middle of the audience, say 50 
ft from the screen, how close could the 
image appear stereoscopically to him, and 
satisfy your requirement? 

Mr. Sherman: Within 4 ft. 

Mr. Hoch: That would apply to, say, 80% 
of the viewing audience? 

Mr. Sherman: About 80% will have the 
visual mechanism and the performance to 
do that, providing it is not sustained, pro- 
viding it's momentary. 

Mr. Hoch: Then there is a time element 
also included? 

Mr. Sherman: Oh, yes. If it were to be 
there for a minute or two at that one spot, 
why some people would feel it, even among 
the 80%. But if it's momentary there 
should be no problem. 



308 



September 1953 Journal of the SMPTE Vol. 61 



Visual Monitor for Magnetic Tape 



By ROWLAND L. MILLER 



This monitor presents visually the information recorded on magnetic tape 
without employing auxiliary equipment such as movable scanning heads, 
amplifiers, etc. The presentation is a variable-area display that indicates 
frequency and amplitude. The display remains stationary as long as the tape 
is motionless in the Magnescope, but movement of the tape is accompanied by 
corresponding movement of the display. Magnescope consists of a unique 
cathode-ray tube and its associated power supply. The cathode-ray tube is 
so constructed that the magnetic fields from the tape directly influence a beam 
of electrons which produces the variable-area display. 



JL HE MAGNESCOPE is a visual monitor 
for magnetic tape. It gives visual pres- 
entation of the information recorded on 
the tape without employing auxiliary 
equipment such as movable scanning 
heads, amplifiers, etc. The presentation 
is a variable-area display and thus gives 
indication of frequency and amplitude. 
The display remains stationary as long as 
the tape is motionless in the Magnescope, 
but movement of the tape is accompanied 
by corresponding movement of the dis- 
play. 

Magnescope consists of two units con- 
nected by a single cable (Fig. 1). One of 
these units houses a unique cathode-ray 
tube which produces the visual display. 
This unit is equipped with proper guides 
to accommodate various magnetic tapes. 
A hold-down mechanism is provided. 



Presented on April 30, 1953, at the Soci- 
ety's Convention at Los Angeles by Row- 
land L. Miller, Magnescope Corp., 1147 
N. McCadden PI., Hollywood 38, Calif. 
(This paper was first received on March 25, 
1953, and in complete form on July 29, 
1953.) 



which, in conjunction with the guides, 
assures correct positioning of the tape. 
Since this unit would normally be in 
front of the user it includes an On-Off 
switch, pilot lamp and fuse. The second 
unit is the power supply and includes all 
adjustable controls. Once the controls 
are adjusted for a particular cathode-ray 
tube there is apparently no reason for re- 
adjustment for the life of that tube. This 
unit normally rests on the floor or any 
other convenient place. 

The cathode-ray tube which produces 
the display is similar in shape to electro- 
static deflection tubes of comparable 
size. At one end of the tube is a gun 
structure. At the other end is a medium 
persistence screen. In between these 
extremities is a metallic section about 4 
in. long which makes the operation of the 
tube possible. 

The gun structure consists of a heater, 
cathode, grid and first accelerating anode 
and, as in conventional cathode-ray 
tubes, the structure supplies the electrons 
and shapes them into a suitable beam. 
The potentials on these various elements 



September 1953 Journal of the SMPTE Vol. 61 



309 





Fig. 1. Experimental demonstration model of the Magnescope. 







Fig. 2. 2-in. and 3-in. tubes. The second anode and saddle can be seen 
near the center of each tube. 



310 



September 1953 Journal of the SMPTE Vol. 61 



are adjusted so that the electron beam 
leaving the gun structure is cone-shaped, 
with the apex of the cone at the first 
anode. 

The forementioned metallic section 
near the center of the tube is the second 
anode, which is specially designed and 
serves several functions. It positions the 
tape (in conjunction with the guides and 
hold-down mechanism), forms the elec- 
trons into a properly shaped beam, and 
accelerates the electrons toward the 
screen after they have been deflected by 
the magnetic fields of the tape. Near 
the center of the anode and at right 
angles to its axis there is a cylindrical 
trough known as the saddle. Figure 2 
shows the second anode and the saddle. 
In the bottom of this saddle is a thin 
window of nonmagnetic material. 
When the Magnescope is in use the mag- 
netic tape passes through the saddle with 
the recorded area directly against the 
window. The magnetic tape, therefore, 
passes through the saddle and at right 
angles to the axis of the tube. 

The cone-shaped beam of electrons 
entering the second anode is formed into 
a ribbon-shaped beam by suitable ele- 
ments in the anode and the electrons in 
this ribbon pass directly underneath the 
window in the saddle. The potential on 
this anode is such that the electrons are 
accelerated toward the screen. The 
electrons, upon striking the screen, pro- 
duce an illuminated band across the 
center of the screen which is parallel to 
the window. In the absence of mag- 
netic tape in the saddle the electrons 
travel in trajectories which are deter- 
mined by the beam-forming elements 
only and pass through the tube to form 
the illuminated band as outlined above. 
However, when the recorded area of the 
tape is placed at the window in the sad- 
dle the magnetic fields surrounding the 
tape extend through the window and 
into the ribbon of electrons directly be- 
low. The introduction of these fields 
changes the trajectories of the electrons 
and the upper edge of the illuminated 



band is now distorted. The amount of 
distortion is a function of the size and 
strength of the individual fields. 

It is not the purpose of this paper to 
analyze the magnetic fields produced by 
the recording on the tape, but the track 
acts almost as if it consisted of very small 
magnets placed laterally across the track 
area and adjacent along its length. 
Continuing this analogy further and 
considering a single frequency only, each 
magnet would be magnetized and have a 
dimension of one-half wavelength in the 
longitudinal direction of the track. 
Furthermore, the magnets would be 
placed with like poles adjacent. ' Each 
magnet (half-wavelength) would have a 
closed external magnetic field between 
its poles, but, due to the placement of the 
magnets with like poles adjacent, the 
directions of these fields will be reversed 
for consecutive magnets. Thus there is a 
reversal of field for each half-wavelength. 

As the electrons enter these fields they 
are deflected toward the tape or away 
from it, depending upon the direction of 
the magnetic field. Since the electron 
deflection is always normal to the direc- 
tion of the field, the deflection upward 
and downward will not be symmetrical 
about an axis. The reason for this is 
that for a recorded sine wave each half- 
wavelength field acts as if it were 
approximately semicircular in shape. 
For a field direction which deflects the 
electrons away from the tape, the elec- 
tron deflection assumes this semicircular 
shape and the bottom half of the cycle is 
approximately semicircular. For the 
other half of the cycle where the field 
direction is such that the electrons are 
deflected toward the tape a different 
situation exists. Because the deflection 
is normal to the semicircular field the 
electrons are deflected toward the center 
of the field as well as upward and this 
half of the cycle assumes a spike shape. 

The net result of this is that for re- 
corded sine waves the display is a series of 
cusps one for each cycle. This effect 
diminishes with decreasing frequency 



Miller: Visual Monitor for Magnetic Tape 



311 




Fig. 3. 100 cycles/sec as seen on the Magnescope. The recording 
circuit was turned on at the peak of the cycle (left side). 



and at frequencies of 100 cycles/sec or 
less the display assumes a sine-wave 
shape (see Fig. 3). At frequencies of 
several thousand cycles/sec the display 
appears almost as a series of spikes. This 
effect is not detrimental to the purpose 
for which the tube is intended, however. 

The area scanned at any one time is 
slightly more than one frame. The 
limit of resolving power is about 6000 
cycles/sec for a 3-in. tube. The ampli- 
tude of the display is about f-in. for a 
100% modulated track. A signal 30 db 
below 100% modulation can be seen. 

Experimental tubes with 2-, 3-, and 5- 
in. screens have been made. In each 
case the geometry of the gun structure 
and second anode is identical. The 2- 
in. tube is about 8J in. long and is in- 



tended to be adapted to existing film 
editing machines to give visual monitor- 
ing for film editors. The 3-in. tube has 
applications outside of the motion-pic- 
ture industry. The 5-in. tube was de- 
veloped for research in cardiology. In 
each case one frame covers the face of 
the tube. The tubes will handle all 
existing track including the "three 
strip." 

Only experimental tubes have been 
made up to the present time and the 3-in. 
tube has been incorporated into the 
Magnescope for display and demonstra- 
tion purposes. The final form of the 
Magnescope has not been determined. 
The needs of the industry must be served 
and these needs will determine its final 
outcome. 



312 



September 1953 Journal of the SMPTE Vol. 61 



Discussion 

George Lewin (Signal Corps Pictorial 
Center)'. Have you given any thought to 
making the track that you're looking at 
audible at the same time, so that it would 
be an additional help to editing? 

Mr. Miller: Yes, we have. However, 
this tube is a static device as well as a 
dynamic one. In other words, the display 
is visible when the track is motionless and 
you see a variable-area picture on the 
tube of what's recorded on the track. Now 
the disadvantage of coupling this directly 
to some audible reproducer is the fact 
that for audible reproduction the track 
must be moving, which, in a sense, defeats 
the purpose of the tube. 

Mr. Lewin: Can't you pick up the beam 
just as you pick up the scanning beam in 
an iconoscope and just the part that's 
stationary would then be repeated over 
and over again if you scanned it slowly 
enough? If you could scan at the speed 
corresponding to its normal tape motion, 
then it ought to give you an intelligible 
reproduction of the particular syllable or 
words that are in the aperture at that 
moment. 

Mr. Miller: Yes. You mean incorpo- 
rate a photoelectric cell into the beam 
somehow. Is that what you meant? 

Mr. Lewin: Either that, or the beam 
itself could be fed into a tube, and ampli- 
fied as it's scanning so as to give you an 
audible signal, provided the scanning is 
kept down to about the speed of the 
normal tape motion. 

Mr. Miller: Yes, that could be done, 
except that there again the tape must 
move at some speed, the speed at which 
it was recorded and when that happens, 
you will not see the pattern of the tape. 
The tube was made to find footsteps, all 
kinds of sound effects, beginnings and 
endings of music and words and blank 
spaces. If the tape moves slowly through 
the tube you can see all of those things. 
If you move the tape at the speed at which 
it was recorded in order to reproduce it, 
then the tube is ineffective. Do you see 
my point? 

Mr. Lewin: Yes, I see your point. It's 
entirely possible that what I have in mind 
is impossible to accomplish. What I 
picture in my mind is that you have this 



electron beam scanning across, say, a 
short piece of the tape. 

Mr. Miller: It's continuous. The elec- 
tron beam is a solid ribbon of electrons 
that goes directly beneath the tape and is 
about a frame wide. There is no scanning. 

Mr. Lewin: I see. I thought it was the 
electron beam scanning across it. 

Mr. Miller: No. We tried using a beam 
and scanning but the resolving power was 
not good, so we gave that idea up. 

Mauro Zambuto (IFE Studios, N.Y.C.): 
I would like to know what happens when 
this gadget is used in connection with 
multiple tracks? Because if I understand 
it correctly, the direction of motion of the 
electrons in the beam is across the width 
of the tape. Therefore if we have a tape 
that has three tracks, one beside the 
other, the beam would be modulated in 
sequence by the signals of each of these 
tracks so that we would have practically 
a mixed signal of the three tracks. 

Mr. Miller: This is a curved section (the 
saddle) and the film follows that curve. 
Now, the track that you are interested in 
is placed directly over this window. The 
other two are far enough removed so 
that they do not deflect the electron beam. 
Then to see either of the other two tracks 
you merely need to re-position the tape 
to select the track you desire to see. 

Mr. Zambuto: That means that the 
active part of the tube is limited to about 
100 mils or less. 

Mr. Miller: That's right. 

Mr. Zambuto: What is the order of 
magnitude of the accelerating voltage in 
the tube? 

Mr. Miller: You mean the speed of the 
electrons? 

Mr. Zambuto: That's right. I mean 
first of all the speed of the electrons near 
the window, and then the speed of the 
electrons when they hit the screen. Is 
there any difference between the two? 

Mr. Miller: They move slowly in this 
region (near the first accelerating anode) 
and then are accelerated after deflection. 

Mr. Zambuto: So the main acceleration 
would happen after this deflection? 

Mr. Miller: That's right. 

Mr. Zambuto: May I ask the order of 
magnitude again? 

Mr. Miller: They hit the screen with a 
velocity of about 20,000 to 25,000 miles 



Miller: Visual Monitor for Magnetic Tape 



313 



per second and in this region near the 
saddle they're traveling about 4000 miles 
a second. If you're interested, a 100% 
track, according to calculations, has an 
external magnetic field of about 1.6 gauss. 

Mr. Zambuto: Exactly 1.6 gauss? 

Mr. Miller: That's what it's calculated 
to be. 

Mr. Zambuto: By external field you 
mean field at the surface of the window? 

Mr. Miller: That's right. 

Mr. Zambuto: And, of course, there is 
something to keep the film in close contact 
with the window? 

Mr. Miller: That's right. There is a 
hold-down mechanism plus some guides 
that rotate and have proper width slots to 
select films of various widths. 

Mr. Lewin: Is there any clear indication 
that can be seen in the display when 100% 
modulation or any specific level on the 
tape is attained? What I'm thinking of 
is whether it can be used to tell how near 
your are to the overload point of the tape. 

Mr. Miller: 100% modulation of the 
tape has been arbitrarily defined as the 
point where 12% intermodulation is 
present when the track is reproduced. 
That has been called 100% modulation 
and represents a certain amount of audio 
power into the recording head. However, 
this power can be exceeded considerably 
without getting too much additional 
distortion. Due to the latitude of the tape, 
it is impossible to determine 100% modula- 
tion precisely by observation. However, 
if you just keep putting on more and more 
level you will come to a point where the 
film evidently becomes saturated, but 
that is way above what is called 100%. 

Mr. Lewin: Do you foresee any possi- 
bility of modifying the tube so the display 
would look like a sine wave? 

Mr. Miller: That's very difficult to do. 
In fact, Dr. A. M. Zarem has asked the 
same question but it's an extremely difficult 
problem. In fact, it may be impossible. 

Francis Oliver (Imperial Productions}: 
Could you tell me what order of magnitude 
of wavelength the tube would be able to 
stand? 

Mr. Miller: At a speed of 90 fpm, 
which is standard motion-picture speed, 
the resolving power is about 6000 cycles. 
Now if the film is recorded at a slower 
speed, say at 45 fpm, the resolving power 



would drop down to approximately 3000 
cycles. This is not a deficiency in the 
tube. It's a deficiency of the eye. You 
just can't see the spikes because they're 
beyond the human resolving power. 

Mr. Oliver: Would there be a possibility 
of spreading this out or magnifying it 
electronically so it could be seen? 

Mr. Miller: Yes. In fact, we made a 
5-in. tube which is being used for research 
in cardiology. Just make the screen larger 
and the tube correspondingly longer and 
the resolving power goes back up. 

Mr. Oliver: I don't know if your com- 
pany has thought about it or not, but the 
computer field probably would have some 
interest in this for read-out equipment to 
display magnetic pulses. That is why I 
was interested in the magnitude of wave- 
length would you estimate 2 mils, 3 
mils, 8 mils in length? 

Mr. Miller: Let's see 6000 cycles is 
what in terms of 90 fpm? 

Mr. Oliver: A mil and a half, something 
like that. 

Mr. Miller: If you use that as a basis .... 

Mr. Oliver: You say 9000? 

Mr. Miller: 6000. Now 7000 and 8000 
are on the tube, but you can't see them with 
the naked eye. 

Mr. Oliver: Well then, you'd say that 
it will resolve, say, 7000 or 8000, and then 
we could magnify it so that we could 
actually display it? 

Mr. Miller: That's right. You could 
do that. 

C. E. Cunningham (U.S. Navy Electronics 
Lab., San Diego, Calif.): So far the device 
described is a qualitative device. Do 
you hope you can make quantitative 
measurements with it? That is, will 
you have a calibration scale on the front 
of the tube? 

Mr. Miller: Yes, a calibration scale 
can be put on it, both in terms of frequency 
and in terms of amplitude. 

Mr. Cunningham: Secondly, what about 
dynamic range? Will it cover the full 
dynamic range of the tapes now in use? 

Mr. Miller: Well, the tube will go up to 
8000 cycles. It is fundamentally an 
electron microscope, and the thing that 
limits its resolving power is the screen 
material. At about 8000 cycles the de- 
flections are comparable to the size of the 



314 



September 1953 Journal of the SMPTE Vol. 61 



material of which the screen is composed 
and the resolving power then disappears. 

Mr. Zambuto: I wanted to know whether 
varying the wavelength affects the vertical 
displacement of the beam on the screen, 
my point being that very high frequencies 
on a tape produce a field that is much closer 
to the tape surface than the field produced 
by a low-frequency signal. Does that 
influence the displacement of the electrons? 

Mr. Miller: Yes it does. For 100% 
recorded levels at all frequencies the 
amplitude is greater at low frequencies 
than at high frequencies. 

Mr. Zambuto: Then it seems to me that 
that would be the element limiting the 
frequency response of the apparatus. 
Because, granted that you can spread the 
beam horizontally by an electronic device, 
you would still be limited by the maxi- 



mum vertical displacement that you can 
get out of a certain wavelength. 

Mr. Miller: That is true, but you will 
still get a usable vertical displacement up 
to 8000 cycles and then the distance 
between the wavelengths becomes com- 
parable to the particle size that makes up 
the screen. Now, by making a longer 
tube and getting effective magnification 
in both directions, vertical and horizontal, 
then you can go on up in frequency. 

Mr. Oliver: Could you tell me the 
diameter of the scanning beam the 
electron beam? 

Mr. Miller: There's a continuous ribbon 
of electrons about a frame wide in the 
horizontal direction and about \\n. thick 
in the vertical direction, and the tape 
rides across the top of that ribbon and 
deflects the upper edge. 



Miller: Visual Monitor for Magnetic Tape 



315 



Westrex Film Editer 



By G. R. CRANE, FRED HAUSER and H. A. MANLEY 



This paper describes a film-editing machine which employs continuous projec- 
tion resulting in quiet operation. It accommodates standard-picture and 
photographic or magnetic sound film as well as composite sound-picture film. 
Differential synchronizing of sound and picture while running, automatic fast 
stop and simplified threading features in the film gates with finger-tip release 
materially increase operating efficiency. 



JL HE WESTREX EDITER has been de- 
veloped to provide facilities for editing 
35mm motion-picture film, in a single 
integrated unit, for meeting the various 
and often conflicting requirements of 
the motion-picture field. The unit de- 
scribed in this paper is the result of exten- 
sive field surveys supplemented by con- 
sultations with many members of the 
film-editing profession in Hollywood. 
Noteworthy among the many improve- 
ments offered by this machine is the 
elimination of noisy operation by the use 
of continuous optical projection and the 
substitution of timing belt drives for 
gear-driven mechanisms. 

It was generally accepted that the 
picture should be projected from the rear 
on a conveniently located screen and 
should be visible through a fairly wide 



Presented on April 29, 1953, at the Soci- 
ety's Convention at Los Angeles by G. R. 
Crane (who read the paper), Fred Hauser 
and H. A. Manley, Westrex Corp., Holly- 
wood Div., 6601 Romaine St., Hollywood 
38, Calif. 
(This paper was received on June 5, 1953.) 



viewing angle and with sufficient screen 
brightness to permit operation in a nor- 
mally lighted room. It is felt that this has 
been accomplished to a very satisfactory 
degree. In addition, means have been 
provided for projecting an enlarged pic- 
ture on a wall, the projection distance 
and resultant picture size being accom- 
modated by the selection of a simple 
spectacle lens. Considerable attention 
has been given to simplicity and 
efficiency in operation and to the con- 
venience of the operator. Threading of 
film has been reduced to a minimum of 
effort. Placing the film in the film trap 
automatically locks the film to the drive 
sprocket so that the position of the film 
cannot be lost inadvertently. Closing 
the film gate completes the operation. 
Removal of the film is accomplished with 
one sweeping motion of the hand. As 
the hand approaches the film, a flat lever 
is depressed which completely releases 
the film. The hand continues in the 
same direction and removes the film. 
Touching a different lever opens the film 
gate without releasing the film from the 
sprocket to permit the film to be inspec- 



316 



September 1953 Journal of the SMPTE Vol. 61 



ted or marked without possible loss of its 
position in the film trap. 

A differential synchronizer permits the 
position of the sound film to be continu- 
ously changed with respect to the picture 
film while the machine is either in mo- 
tion or at rest. Associated with the 
differential synchronizer is a dial which 
counts the number of frames required for 
synchronism in either direction. 

The sound sprocket is driven by a sub- 
stantially constant-speed motor which is 
controlled by a foot-pedal switch op- 
erated by the left foot. The picture 
sprocket is driven by a variable-speed 
torque motor which is controlled by a 
foot-pedal switch and rheostat operated 
by the right foot. The film sprockets 
can be operated independently by their 
respective motors, or the two sprockets 
can be mechanically interlocked by the 
operation of a lever and driven by either 
motor in the forward or reverse direction. 
Four illuminated arrows indicate whether 



each motor circuit is set for forward or 
reverse operation and a fifth arrow indi- 
cates whether the two sprockets are inter- 
locked. 

General Description 

Figure 1 is a front view of the Editer. 
The main housing is an aluminum cast- 
ing which is supported by two formed 
sheet-metal legs. The height is adjust- 
able over a range of 5 in. to accommodate 
the operator in seated or standing posi- 
tion. The two foot pedals are also ad- 
justable back and forth to suit the oper- 
ator. Four castors provide mobility 
while two jack screws insure operation in 
a stationary position when desired. The 
large raised section at the center of the 
main casting houses the viewing screen 
and two of four take-up spindles which 
are optional accessories for operation 
with 10-in. film reels. An incandescent 
lamp, located within this housing and 
operated by a push-on, push-off button 



Fig. 1. Front view showing 
operation with film reels and 
bag at the rear for collecting 
film if reels are not used. 




Crane, Hauser and Manley: Westrex Film Editer 



317 




Fig. 2. Close-up of front showing operating controls. 



switch, provides a shadow box for view- 
ing film. The hood over the viewing 
screen is useful where a high level of 
room lighting exists, but is readily folded 
back or removed. 

The lower take-up assembly between 
the legs is likewise optional and not pres- 
ent if operation without reels is desired. 

A sheet-metal box connects the two 
legs at the rear near the floor, which pro- 
vides structural stiffness and convenient 
housing for most of the electrical com- 
ponents. A removable rear panel gives 
ready accessibility to fuses, relay and 
amplifier. All wiring to the upper hous- 
ing passes through plug connectors. 

Controls 

Figure 2 is a close-up view of the main 
housing showing the location of the parts 
of the equipment and the controls which 
are used in normal operation of the 



Editer. The center section starting from 
the top contains the viewing screen, the 
five indicator lights, the light-box lamp 
switch and the circuit control panel. 
This panel is equipped with sound and 
projection-lamp switches, a photo- 
graphic-to-magnetic sound-transfer 

switch, a switch which operates the con- 
stant-speed motor or transfers the con- 
trol to the foot pedal, a main power 
switch, a volume control and a jack for 
phones. To the left of the center section 
are the reversing switch and handwheel 
for the constant-speed motor and the 
differential-synchronizing control. In 
front of these is the monitor loudspeaker. 
To the right of the center section are the 
reversing switch and handwheel for the 
variable-speed motor, and the framing 
control. In front of these is the footage 
counter reading in feet and frames. An 
optional, additional counter reading sec- 



318 



September 1953 Journal of the SMPTE Vol. 61 




Fig. 3. Close-up showing removable, prefocused lamp mounts. 



onds of time is mounted just below the 
footage counter. The sound and projec- 
tion lamps are mounted in cartridge-type 
lamp mountings which are quickly re- 
movable from the front of the machine 
for replacement of lamps, as shown in 
Fig. 3. Both holders are keyed for 
registration and held by detents so that 
no tools or readjustments are required. 

Just above the control panel is a lever 
which rotates through 180 to interlock 
the sound and picture drive mechanisms. 
It operates a coupling consisting of an 
internal gear meshing with an external 
gear of the same number of teeth, and a 
one-tooth interval in mesh is equivalent 
to one sprocket hole. The engagement 
is spring loaded by the control lever and 



the indicator light is lighted only when 
actual mesh is achieved, which may 
require the rotation of one shaft by a frac- 
tional tooth pitch. A high-speed rewind 
flange is located on the left side of the 
machine and is normally operated by the 
constant-speed motor. Several features 
of the Editer are sufficiently interesting to 
merit a more detailed description. 

The picture system employs continu- 
ous projection by means of a rotating 1 2- 
sided prism, thus eliminating the noise 
introduced by the conventional type of 
intermittent movement. The picture 
image is projected from the rear on a 
translucent screen with sufficient light 
intensity to permit operation in the 
presence of normal room illumination. 
The image is 3f X 5 in. of the same 



Crane, Hauser and Manley: Westrex Film Editer 



319 



OPTICAL 




Fig. 4. Optical schematic, simplified by the omission of several mirrors. 



orientation as the image on the film; 
that is, the film in the gate is threaded so 
as to appear upright and properly ori- 
ented from left to right and this relation- 
ship is maintained in the projected image 
on the screen. The quality of the image 
is comparable to that obtained with inter- 
mittent-type systems. The movement of 
a lever shifts the picture to the right 
enough to include a view of the sound 
track of a composite print. 

If desired, an enlarged image can be 
projected on a wall or screen by operating 
two controls. A knob control inserts a 
simple spectacle lens in the optical path 
below the projection lens and a second 
knob tilts one mirror. This supplemen- 
tary lens is introduced to focus the pro- 
jected picture without disturbing adjust- 
ments of the normal optical system, and 
its focal length may be chosen to accom- 
modate any given distance. In this case 
the orientation of the projected image is 
also the same as that of the image in the 
gate. The image size is a function of the 
distance between the machine and the 
screen, and for a distance of 10 ft the 
picture is approximately 15 X 20 in. 

Optical System 

The continuous-projection optical sys- 
tem is shown schematically in Fig. 4. 
The filament of the projection lamp is 
imaged in the objective lens by a three- 
element condenser lens. Two heat- 



absorbing filters are located between the 
elements of the condenser lens, and these 
filters are sufficiently effective to permit 
the film to remain stationary in the pic- \ 
ture gate for an indefinite period without 
causing damage to the film. A blower 
passes sufficient air over the lamp and 
condenser-lens assembly to remove heat 
and keep the entire assembly cool. A 
mirror in the picture gate bends the 
optical axis at a right angle and directs it 
through a rotating 12-sided prism. A 
second mirror deflects the light beam 
into the objective lens which focuses the 
film image on the viewing screen. Two 
additional mirrors (not shown in the 
schematic) fold the beam for conve- 
nience. The prism is driven directly from 
the picture-sprocket shaft by right-angle 
helical gears. Framing is accomplished 
by sliding the drive gear along the shaft 
to alter the angular relationship between 
the prism and the sprocket. Several re- 
finements in design reduce gear backlash 
to a minimum to insure picture steadi- 
ness. 

The function of the prism in this sys- 
tem for continuous, nonintermittent 
projection is similar to systems employed 
in high-speed cameras and projectors, 
and the fundamental design considera- 
tions have been well covered in previous 
articles 1 and will, therefore, not be re- 
peated here. The authors also acknowl- 
edge the significant contribution of L. B. 



320 



September 1953 Journal of the SMPTE Vol. 61 




FREE ON SHAFT 



Fig. 5. Simplified mechanical schematic to illustrate use of epicyclic gears 
to permit changing the position of one film sprocket relative to the other. 



Browder in the design of this optical sys- 
tem. 

The various considerations of perform- 
ance and manufacture indicate that the 
best compromise is a prism having 12 
faces. Each face is active for a total 
rotation of the prism of 30 or plus and 
minus 15 from normal, plus the angle 
subtended by the objective-lens aperture. 
This aperture takes the form of a slit with 
its long dimension parallel to the axis of 
the prism to keep its subtended angle at a 
minimum, consistent with reasonable 
light conservation. However, due to 
this aperture effect, successive frames are 
projected as lap dissolves, the overlap 
being of short duration, representing the 
time required for the edge between two 
prism faces to pass across the effective 
width of the lens aperture. The prism is 
shown in Fig. 6 with the adjacent mirror 
D which turns the axis downward 
through the objective lens. This mirror 



is rotatable between stops to shift the 
image for viewing the sound track. The 
shift lever is shown as E. 

Synchronization Control 

Differential synchronization between 
the sound and picture films is accom- 
plished by a series of gears on the jack 
shafts in the sound and picture film 
drives. With the two shafts interlocked, 
synchronization may be changed by 
indicated amounts while the machine is 
in operation or at standstill. Figure 5 is 
a simplified mechanical schematic of the 
differential synchronizer. A represents 
the sound jack shaft on which a gear B is 
mounted ; G represents the picture jack 
shaft on which a gear D is mounted. 
The gears B and D are coupled through 
an integral pair of epicyclic gears E, the 
shaft of which is mounted on the carrier 
F. This assembly floats on the jack 
shaft and may be rotated about it by the 



Crane, Hauser and Manley: Westrex Film Editer 



321 




Fig. 6. Close-up of picture film trap, showing method of threading film. 



worm and gear H and G and the manual 
indexed control I. The pair of epicyclic 
gears have different gear ratios and in 
consequence, when the carrier is rotated 
about the jack-shaft center, the sound 
film is advanced or retarded with re- 
spect to the picture film. 

Film Traps 

Figure 6 is a view of the picture-film 
trap and gate and illustrates the method 
of threading. The film is held between 
the two hands and laid in the film trap 
under light tension to sense the engage- 
ment of the sprocket teeth with the holes. 
The thumb is then in a position to press 
the film down and operate a trigger but- 



ton shown at A which causes two film- 
retaining slides to move over the edges of 
the sprockets and retain the film in en- 
gagement. One of these slides may be 
seen as B. Closing the gate F com- 
pletes the threading. The latter is held 
closed by the lever G, which may be 
operated at any time to release the gate 
but not the film-retaining slides. This 
permits ready access to the full area of 
the film for marking without losing syn- 
chronization. Depressing the upper 
lever C opens the gate and releases the 
film simultaneously. 

For synchronizing purposes, the hand- 
wheel is turned to index any one frame 
with a reference arrow located in the 



322 



September 1953 Journal of the SMPTE Vol. 61 



center of the picture aperture, the arrow 
also being projected onto the viewing 
screen. The picture gate contains only a 
mirror for bending the light path. As 
shown by Fig. 3, the single screw A per- 
mits removal of the entire lamp mounting 
assembly, and the screw B releases the 
complete condenser and heat filter 
assembly for cleaning. 

Sound Reproduction 

The quality of reproduced sound is 
considerably better from the standpoint 
of frequency characteristic, signal-to- 
noise ratio and flutter than that which is 
usually associated with film-editing de- 
vices. The optical-scanning system is 
substantially the same as that in general 
use in theater reproducers. The mag- 
netic head is a conventional commercial 
type. A four-stage amplifier is used for 
photographic sound reproduction and 
one additional stage is connected for 
magnetic reproduction with magnetic- 
reproducing equalization provided. 
The photographic input circuit contains 
a narrow dip filter tuned to 1 20 cycles to 
attenuate the light modulation resulting 
from operating the sound lamp on a-c. 
This feature combined with the relatively 
high thermal inertia of the 7.5-amp lamp 
gives a saitsfactory signal-to-noise ratio 
for this use. A tone control is provided 
on the amplifier and its knob appears 
through the top of the equipment box. 
An output jack is also provided at this 
point to plug in an extension speaker to 
be used with wall projection if desired. 

Motors 

The picture film is driven by a vari- 
able-speed torque motor which in com- 
bination with the foot-pedal resistance 
control is capable of driving the film at 
variable speeds from essentially stand- 
still to double normal speed and is in- 
stantly reversible while running. 

The sound film is driven by an induc- 
tion motor, which is substantially con- 



stant speed, and is equipped with an 
electrical brake. A circuit is arranged 
to charge a condenser with rectified a-c 
from the line. When the foot pedal is 
released, back contacts on the switch 
connect the charged condenser to a relay 
coil and operate it for a short intri\,il 
which is determined by the discharge 
rate of the condenser and (lie associated 
circuit. The relay momentarily con- 
nects a second charged condenser across 
the field winding of the motor, and, de- 
pending on the adjustment of a current- 
limiting resistor, the motor can be 
stopped within two picture frames. This 
type of braking is fully automatic and 
has the advantage of having no braking 
torque applied when the machine is 
turned by the handwheel. 

In conclusion, it is felt that the Westrex 
Editer will fill a long-existing need of the 
motion-picture industry for modernized 
film-editing facilities with increased 
efficiency and improved convenience in 
operation. 



References 

1. F. Ehrenhaft and F. G. Back, "A non- 
intermittent motion picture projector," 
Jour. SMPE, 34: 223-231, Feb. 1940. 

2. F. Tuttle and C. D. Reid, "The problem 
of motion picture projection from con- 
tinuously moving film," Jour. SMPE, 
20: 3-30, Jan. 1933. 

3. Howard J. Smith, "8000 pictures per 
second," Jour. SMPE, 45: 171-183, 
Sept. 1945. 

4. J. Kudar, "Optical problems of the 
image formation in high-speed motion 
picture cameras," Jour. SMPE, 47: 400- 
402, Nov. 1946. 

5. J. L. Spence, "An improved editing 
machine," Jour. SMPE, 31: 539-541, 
Nov. 1938. 

6. John H. Waddell, "Design of rotating 
prisms for high-speed cameras," Jour. 
SMPE, 53: 496-501, Nov. 1949. 

7. Charles W. Wyckoff, "Twenty-lens 
high-speed camera," Jour. SMPE, 53: 
469-478, Nov. 1949. 



Crane, Hauser and Manley: Westrex Film Editer 



323 



A Nonintermittent Photomagnetic 
Sound Film Editor 



By W. R. HICKS 



The editing of magnetic sound tracks by visual and aural methods has become 
increasingly important because of the rapid adoption of the magnetic system 
by the industry, both for primary recordings and theater release. Three- 
dimensional theatrical and multicamera television films have also stressed 
the need for editors which show more than one picture. A solution is sug- 
gested for these problems and a system of electronic editing is proposed, 
leading to an enlargement of editing processes to include sound recording, 
re-recording and dubbing, formerly limited to the sound studio. 



JL HE DEVELOPMENT of magnetic sound 
recording has greatly influenced the 
technical handling and treatment of 
sound tracks following the general 
acceptance of the magnetic system by 
motion-picture producers. Initially, the 
magnetic track was approved for primary 
recordings because of its high signal-to- 
noise ratio, low distortion and ease of 
playback. But invisible magnetic tracks 
were impossible to edit by conventional 
sight methods, and magnetic recording 
required transfer to photographic tracks 
for subsequent editing, mixing and 
release on photographic equipment. 
Various systems for visualizing the re- 
corded magnetic track were tested to 
facilitate direct track editing. Some 
early methods featured the use of 
magnetic inks and wet solutions con- 
taining carbonyl iron, but these were 
in general awkward and sometimes 
messy and were superseded by auxiliary 

Presented on April 29, 1953, at the Society's 
Convention at Los Angeles by W. R. Hicks, 
Centaur Products Corp., Manhasset, N.Y. 
(This paper was first received May 5, 
1953, and in revised form July 2, 1953.) 



visual track systems, including a combi- 
nation of parallel magnetic and photo- 
graphic sound tracks or companion 
inked tracks traced directly on the 
magnetic film, this system being known 
as modulation writing. 

With these aids the motion-picture 
editor now cuts and assembles magnetic 
tracks in much the same manner as 
photographic tracks, on familiar equip- 
ment adapted for magnetic-track scan- 
ning. Editing by sight methods, he 
depends upon his magnifying glass or 
optical loop, but he must still check 
finished cuts audibly on machines with 
low-quality sound-reproducing elements 
and high flutter and mechanical noise. 
The word endings of a photographic 
track or visualized magnetic sound track 
are not easily seen when the frequency 
is high and modulation low. Cutting 
errors often result which are difficult 
to detect audibly on small loudspeakers 
and amplifiers of limited frequency range 
and when mechanical noise reduces 
intelligibility. Later listening under the 
high-quality conditions of a mixing 
room or theater often discloses missing 



324 



September 1953 Journal of the SMPTE Vol. 61 



"ess" sounds, faultily de-blooped splices 
and unwanted stage background noise. 
In many cases, after preliminary re- 
hearsal a reel with its multiple sound 
tracks must be returned to the cutting 
room for further work. 

For critical listening the editor needs 
equipment with performance at least 
comparable to the machine and elec- 
tronic elements of the mixing room. 
This is especially true when auxiliary 



sight-cutting tracks are unavailable be- 
cause of added cost, and the invisible 
magnetic track must be edited directly 
by listening methods alone. 

The editor described has been de- 
signed to meet these requirements. 
Mechanical noise has been reduced by 
minimizing gear components. Uniform 
film motion with low flutter is stressed, 
and the reproducing amplifier, power 
supply and loudspeaker system are 




Fig. 1. Editor twin with sound side threaded and mounted 
on barrel pedestal with foot-treadle and touch-plate controls. 



Hicks: Nonintermittent Photomagnetic Editor 



325 



/K\ 




Fig. 2. Editor twin showing sound side threaded, footage counters, motor 
and lamp controls, screen and loudspeaker frames. 



engineered to equal the performance of 
similar units in a studio equipment 
group. Film scratches, abrasions and 
perforation deformation are minimized 
by the wide use of fluoroethylene plastic 
in rollers and shoes, combined with a 
dependable, nonintermittent system of 
picture projection. A welded metal 
case houses all drive components and 
electronic equipment and encloses the 
picture-projection path. Operating con- 
trols are grouped on the front of the 
case which contains a rear-vision screen, 
loudspeaker and footage counters. The 
case sides serve as mounting walls for 
separate work-print and sound-track 
film transports complete with torque- 
motor driven reel spindles and cast 
assemblies for the alignment of sprockets, 



pad rollers, photographic and magnetic 
sound-scanning units and the picture- 
projection and imaging optical systems. 
Coupling knobs on each side select 
either or both transports, with per- 
manently linked footage counters for 
record purposes. In addition, a com- 
pact assembly on the sound side facilitates 
aural magnetic-track editing. 

Dynamic Scanning 

Magnetic tracks are normally re- 
produced or scanned by running film at 
a uniform speed past a stationary 
magnetic head in contact with the 
magnetic' coating. Track scanning is 
also feasible if the film is held stationary 
and the head moved while maintaining 
contact with the coating. This method 



326 



September 1953 Journal of the SMPTE Vol. 61 



is used in the editor dynascanner, which 
employs a magnetic head rotating 
within a film-wrapped drum and con- 
tacting the magnetic coating along a 
film length corresponding to from two 
to five spoken words. Twin guide rollers 
determine the drum wrap which is an 
integral part of the film path. Head 
rotation is controlled by a small syn- 
chronous drive motor operated by a 
switch on the control panel. 

In operation, a magnetic track roll 
is threaded on the sound side and run 
against the work print with the scanner 
drum rotating and the head stationary. 
Word endings are located by stopping 
the machine, decoupling the sound side 
and powering the head drive motor. 
The drum is now stationary and the 
head rotates continuously, reproducing 
only the portion of the magnetic track 
which wraps the drum. A knob on the 
film sprocket is then turned slowly to 
position the exact word end at a point 
on the drum where the moving head 
leaves the coating. Engraved frame 
lines on the drum face assist the editor 
in marking the film for future cutting. 
Word beginnings are found and marked 
in the same manner. 



Recording and Copying 

The producer who cannot assume the 
risk of cutting an irreplaceable original 
magnetic sound track must re-record, 
or copy it. The copying process requires 
a magnetic reproducing or "dubbing" 
machine, an electronic audio-control 
channel, a magnetic recording machine 
and a monitor system. The producer 
usually rents the facilities of a sound- 
service studio and pays rental fees plus 
film costs for the copying service. If 
he uses the auxiliary sight-cutting track 
method he finds his track-cutting costs 
rising sharply above the standard photo- 
graphic sound work-print costs which 
were part of his earlier budgets. 

Should he decide to do his own mag- 
netic-track copying and edit the copied 
track by dynamic-scanning methods 
without visual aids, he must have 
equipment which technically approaches 
the quality of units in the service studio. 
This equipment requisite, with one 
addition, is supplied by the basic editor 
twin, which has been designed to operate 
with a small, complementary console 
recording amplifier (Fig. 3), to perform 
a wide range of recording and re- 
recording operations. 




Fig. 3. Mite recording amplifier showing control panel and input and 
output receptacles. 



Hicks: Nonintermittent Photomagnetic Editor 



327 



The console amplifier is housed in an 
aluminum case with detachable cover, 
with carrying handle and neck strap 
for transport. Power is supplied from 
dry batteries of the portable type but 
large enough for operation over an 
extended period. The amplifier gain 
is in excess of 100 db, and contains a 
high-frequency oscillator and mixer 
stage for direct cabling to a magnetic 
recording head. Output cable lengths 
up to 25 ft in length are practicable, as 
the bias voltage is read on the panel 
volume-indicator meter and is adjustable 
from a panel knob. Input im- 
pedances of 50, 250 and 500 ohm are 
available for low-impedance micro- 
phone use. A record-re-record switch 
on the panel is provided for microphone 
recordings or editor copying work. In 
the re-record position only the output 
stage and bias oscillator are powered. 
A second record-rehearse switch powers 
the oscillator for extended rehearsal 
periods, and also disconnects the volume 
indicator. Oscillator tank and coupling 
coils are of high Q, mounted in a shielded 
case containing tunable capacitors. Re- 
cordings cannot be made with the switch 
in the rehearsal position, and the opera- 
tor is always certain recording is taking 
place when the volume indicator is 
operating. Batteries are accessible by 
removing a screw and folding back half 
of the amplifier control panel. Amplifier 
response is flat to 9000 cycles/sec and 
intermodulation products are less than 

1%. 

The case cover contains a crystal 
earwig monitor unit with cord and 
jack, microphone and output cables, 
microphone, desk stand and a tripod 
capable of elevating the microphone 
7 ft above floor level. The tripod is 
also adaptable for use as a hand-held 
microphone extension pole 8 ft in length. 
The complete case is 10.5 in. long, 3 in. 
wide and 8.5 in. high, and weighs 
10.25 Ib. 

There are many uses for a recording 
editor and console which do not demand 



personnel with engineering experience. 
The film editor employs the magnetic 
track for voice comments and advice 
to the producer at a rough work-print 
showing, to the composer who will 
write a score, or to the special-effects 
department for spotting wipes and 
dissolves. With even reasonable care 
it is a simple matter to record a narration 
track, and a variety of sound effects can 
be made, synchronized with work-print 
action, if desired. The console amplifier 
suffices for this work, and is suitable 
for basic stage-dialogue recording. 

More complicated mixing consoles 
are necessary for involved procedures, 
as are additional sound reproducers. 
Matching sound twins are provided 
for this purpose, serving as additional 
editing heads in the cutting room and as 
multiple copying machines when 16mm 
magnetic-striped release prints are 
needed in quantity. Each machine is 
equipped with the synchronous-interlock 
variable-speed motor developed es- 
pecially for the editor twin, insuring 
frame-for-frame synchronism between 
all machines without additional dis- 
tributor or master control equipment. 
Any combination of 16mm, 17.5mm 
and 35mm tracks is possible for multireel 
editing and synchronizing. 

When a sound twin is used in interlock 
with a twin editor many unusual combi- 
nations are available for projection, 
recording and re-recording. One of 
the most interesting from the standpoint 
of the film cutter and sound engineer 
is the possibility of "cutting" sound tracks 
electronically, without having recourse 
to the scissors or film splicer. An entire 
dialogue reel can be assembled by 
matching the opening picture scene 
with its associated photographic or 
magnetic sound track on the editor, 
followed by re-running and re-recording 
to a separate magnetic film on the sound 
twin, used as a recorder. Following 
picture scenes are cut and spliced as 
desired, then matched with sound tracks 
which are reproduced on the editor 



328 



September 1953 Journal of the SMPTE Vol. 61 



and recorded magnetically on the sound 
element. Previously recorded tracks are 
played back with previously cut and 
spliced picture scenes of the roll under 
assembly, and the following track is re- 
produced, recorded and monitored in- 
stantaneously when the rehearse-record 
switch on the control console is operated. 
In this manner original magnetic sound 
tracks can be preserved on the same 
film roll on which they were originally 
recorded. 

Such a system is especially valuable 
for the assembly of sound tracks which 
have been recorded against picture loops 
in the well-known dubbing, or foreign- 
version scoring process. The illuminated 
footage counter with frame wheel is an 
accurate manual-switching reference, 
but sound sequences separated by five 
frames may be re-recorded automatically 
when a splice-actuated microswitch 
on the editor picture side is used. This 
switch controls a speech relay of the 
sequence type, which also stops the 
recording when the scene ends. All 
tracks are reproduced by the standard 
editor amplifiers, and the auxiliary 
recording console connects directly to 
the erase and record heads of the sound 
twin during recording. 

Editor Amplifier 

A fully equipped editor twin is fur- 
nished with separate photographic and 
magnetic scanning elements on the 
sound and picture sides. The head and 
photocell leads connect to inner 
case receptacles mating with connectors 
on the plug-in amplifier chassis. The 
chassis and amplifier control panel are 
combined in an assembly for case 
closure, with jacks, volume controls, 
switches and fuses appearing on the 
panel. Power and motor-control re- 
ceptacles are divorced from the amplifier 
and mounted on the rear of the case 
above the amplifier panel. Four two- 
stage preamplifiers, each with low- 
and high-frequency compensating feed- 
back loops, are used to amplify the 



output signal of the magnetic heads 
and photocells. Individual potentiom- 
eters control loudspeaker editing vol- 
ume, or track levels during re-recording. 
Photocell volume controls are combined 
with exciter lamp switches; lamp cur- 
rents are not changed when one or both 
lamps are used. 

Closed circuit jacks on the panel 
connect the magnetic heads to the pre- 
amplifier inputs, so that either head 
may be cabled to the output of the re- 
cording console by a phone plug and 
cord. Separate 8-ohm, 500-ohm and 
headset jacks terminate the amplifier 
output. The 500-ohm circuit is used 
for re-recording with the console and 
for connection to the power amplifier 
and loudspeaker of monitor or review- 
room equipment. The 8-ohm jack 
normals to the speaker in the editor case 
and is used for external connection to 
a larger loudspeaker. Provision is 
made for the use of a headset when 
circumstances prohibit loudspeaker 
operation in a cutting room where 
several machines are active. The ampli- 
fier tube heaters as well as the exciter 
lamps are supplied with d-c from 
separate rectifier systems. The amplifier 
plate rectifier tube and filter components 
are on the chassis but the power trans- 
formers, selenium stacks and low-voltage 
filter components are remotely mounted 
in the editor case, connected to the 
amplifier through the mating receptacles. 
A neon pilot lamp on the panel lights 
to indicate failure of the amplifier fuse. 

At the 2-w rated output, a signal-to- 
noise ratio in excess of 55 db is achieved, 
with intermodulation products of less 
than 1%. Amplifier gain is 105 db 
with a flat response from 30 to 10,000 
cycles/sec. Output power is more than 
ample for operation of the case loud- 
speaker, and is sufficiently high to drive 
a remote speaker of larger size at sound 
levels associated with medium review 
rooms. 

Lower-performance amplifiers are also 
furnished with integral power supplies. 



Hicks: Nonintermittent Photomagnetic Editor 



329 



Frequency response and distortion are 
similar but signal-to-noise ratio is limited 
to 35 to 40 db. Noise ratings include 
magnetic heads connected to the ampli- 
fier inputs. 

Design Elements 

The exciter lamp, sound optical 
system and magnetic head needed for 
photographic and magnetic track re- 
producing have been combined in a 
compact assembly with all requisite 
focusing and adjustment controls. The 
prefocused exciter-lamp mount includes 
a push button which relieves spring 
pressure for replacement. A slitless 
lens system has accurate azimuth adjust- 
ing screws, and the entire assembly is 
movable micrometrically for focus and 
track location. The emulsion planes 
of standard and nonstandard prints are 
selected quickly by a limited-throw 
angle lever. 

A subassembly mounts the retractable 
magnetic head, with adjustments for 
azimuth, track location, tangent posi- 
tioning and film-plane contact. The 
head is controlled by a detented selector 
knob on the assembly-casting cover. 
A single knurled screw fastens the cover, 
which is grilled for lamp ventilation. 

In combination with a photoemissive 
cell on the film-transport assembly and 
the compensated preamplifier the photo- 
graphic scanning system reproduces 
16mm tracks with a range of 40 to 7000 
cycles/sec without deviation. The mag- 
netic scanning head and its associated 
preamplifier reproduce magnetic sound 
tracks faithfully over a range of 40 to 
9500 cycles/sec. A complete photo- 
magnetic scanner assembly is furnished 
on the sound and picture sides of a 
fully equipped editor twin. 

Projection and Imaging Optics. A separate 
assembly houses the projection lamp, 
reflector, heat absorbing phosphate and 
aspheric-condenser lens for projection. 
The standard 100-w prefocused lamp 
may be replaced by 200- and 300-w 
lamps for large-screen wall projection. 



The aspheric-condenser element images 
the lamp filament in the aperture of the 
objective lens. Two first-surface mirrors 
in slab mountings reflect the illuminated 
film frame to a rear-vision daylight 
screen 5 X 7.5 in. A 90 rotation of 
the initial mirror reflects the picture at 
right angles to a wall screen. All glass 
parts are accessible for cleaning. 

Nonintermittent Picture Projection. The 
continuous projection of a motion- 
picture frame sequence with a multi- 
faceted prism has depended on the 
principle of control of prism rotation by 
the moving film, and has demanded 
gearing of extreme precision. The editor 
operates with a conventional twelve- 
sided prism, gear connected to two film- 
registering sprockets. A Gilmer pulley 
on the prism shaft is connected by a 
timing belt to a low-speed motor-driven 
pulley, and a combination aperture 
plate and pressure shoe produces tension 
in the film which cancels gear backlash. 
The film is side guided at the shoe to 
eliminate weave. 

Drive Motor. For flexible operation, 
either alone or with other units, a single 
drive motor was developed for the editor 
by W. R. Turner. The motor runs 
synchronously at 1800 rpm, variably 
over a range of to 3400 rpm and in 
synchronous interlock with the motors 
of other machines. Forward and reverse 
operation is controlled manually by a 
toggle switch on the front panel or by 
treadle switches or foot touch plates 
mounted in several types of pedestal 
bases. 

Because of the positive nature of 
the interlock design all machines can 
be started, stopped and restarted without 
loss of synchronism. Machines of various 
types may thus be grouped for operation 
without dependence on coupling shafts, 
common bases or tables. The motor 
is powered from standard 110/115-v, 
1 -phase, 60-cycle mains, and is also 
supplied for 50-cycle use. 

Decoupler Knobs and Footage Counters. 
The picture and sound sides may be 



330 



September 1953 Journal of the SMPTE Vol. 61 



run in mechanical lock or individually, 
by operation of the decoupler knobs. 
A slight pull out and 90 twist dis- 
connects the film-transport sprocket shaft 
from the low-speed motor shaft, allowing 
the sprocket knob to be turned freely 
for film movement. Cove-mounted 
footage counters are permanently con- 
nected to the sprocket shafts of the 
sound and picture drives, operating 
independently of the decouplers. The 
counters have four digit wheels and a 
forty-frame wheel, and are illuminated. 

Reel Spindles and Controls. The spindle 
torque motors are powered by the action 
of lift rollers on the case sides. After 
threading, the operator rotates the film 
reels manually to eliminate slack, raising 
the lift rollers. As the rollers lift, micro- 
switches supply power to the spindle 
motors, maintaining the film to and from 
the sprockets under tension. When 
film runs out the falling lift rollers dis- 
connect the motors and the reels come 
to rest. The lift rollers are also used 
for high-speed rewinding and winding 
under the control of a panel toggle 
switch. Each motor is cradled in a 
bracket for axial tilting against a balance 
spring. A weight increase of the reel 
due to added film lowers the motor 
position and actuates a microswitch on 
the bracket. Spindle torque is influenced 
by two capacitors, selected by the switch. 
The motors are not connected with the 
wiring of the drive motor, and do not 
operate when hand-held rolls are 
threaded. The spindles accept standard 
400-, 800- and 1200-ft reels. 

Pedestals. Hand-held rolls exit from 
the machine directly downward to 
eliminate lengthy guide chutes. Picture 
and track takes double wound on a 
single roll are easily fanned out and 
side threaded, dropping into twin 
cotton barrel liners in the base. The 
barrel bottom contains five single-ball 
antifriction casters for floor clearance, 
movement and rotation. A circular 
floor mat with double race rails may be 
used under the barrel for rapid center 



swiveling. Handles and foot-operated 
locking pads are standard equipment. 

A metal-case pedestal matching the 
dimensions of the editor base is also 
supplied with a tilting top and formed 
rods for side cotton bags. Both bases 
are fitted with foot touch plates vertically 
mounted for start-stop and forward- 
reverse motor control. Receptacles par- 
alleling the touch-plate switches are 
provided for connecting sloping foot 
treadles or hand-held pear-button 
switches. The base design accepts indi- 
vidual splicers on folding drop leaves 
for direct film cutting without removal 
to a splicing table. 

Rollers and Shoes. The tetrafluoro- 
ethylene resin (Teflon) used in the con- 
struction of the rollers and shoes possesses 
several remarkable properties. It has 
high adhesive resistance, with a waxy 
surface on which nothing will stick. It 
is highly inert chemically. Machined 
in roller form it repels dirt particles 
that might scratch film emulsions. In 
shoe form it safely changes film direction 
without scoring or unusual deformation. 
It is nonflammable and has a service 
range of from minus 320 to plus 500 F. 
The Teflon rollers used are bushed 
with oilless bearings and have pressed 
anodized Duralumin side flanges. 

The editor case design and picture- 
projection system permit the use of 
either side, or both, for picture-film 
transport and projection. By increasing 
the case width, two picture screens may 
be installed for the simultaneous pro- 
jection of long shot and close-up camera 
takes. The production of films for 
television stresses the two-camera tech- 
nique, and the editing of both films on 
a common machine with side-by-side 
pictures aids the cutting process. An 
interlocked sound twin is used for sound- 
track matching. 

The double-side picture-projection 
system has also lessened the difficulty 
of editing and assembling three-dimen- 
sional 35mm films. A single screen is 
used with the projection throws super- 



Hicks: Nonintermittent Photomagnetic Editor 



331 



imposed, and the screen is viewed con- 
ventionally through polarized glasses 
or through an extension jib-mounted 
polarized septum viewer. An inter- 
locked sound twin for three-track mag- 
netic-track reproduction is supplied, 
with three loudspeakers in a composite 
wall baffle. The review of films with 
high aspect ratios requires only the cor- 
rect aperture and the addition of any 
specified magnetic-head type with mul- 
tiple amplifiers and speakers. 

Magnetic sound tracks were once 
considered valuable only as a pre- 
production aid. Their eventual use 
on release prints, either 16mm or 35mm, 
was discounted because of the vast 
problem of equipment modification and 
replacement. It is now apparent that 
this problem may be solved in the very 
near future. Magnetic projectors for 
reproducing 16mm magnetic edge- 
striped prints are already in wide use. 
Multiple magnetic stripes on 35mm 
prints are featured by CinemaScope and 
similar systems and theaters are now 
being rapidly equipped to show these 
films. Cinerama has demonstrated the 
practicability of recording and playing 
back with six magnetic sound tracks in 
a system which has discarded photo- 
graphic sound completely. Three-di- 
mensional films have been released 
accompanied by separate magnetic sound 
rolls using three tracks which require 
a magnetic reproducing machine inter- 
locked with a projector in the theater 
booth. A large number of theaters are 
now making such installations. Tele- 
vision networks depend upon an inter- 
locked magnetic sound reproducer for 
kmescoped programming and will un- 
doubtedly adopt the magnetic-striped 
release print at a later date. 

Because of its adaptability to the 
many phases of picture and sound edit- 
ing, sound recording, re-recording and 
magnetic-print production, the editor 



and its associated units would appear 
to merit the close study of motion- 
picture producers. 

Acknowledgments 

The author sincerely appreciates the 
assistance of G. J. Badgley, U.S. Naval 
Photographic Center, Dr. E. C. Fritts 
of the Eastman Kodak Co., and Dr. 
Franz Ehrenhaft of Scanoptic, Inc. 

Discussion 

George Lewin (Signal Corps Photographic 
Center): Could you clarify the function of 
the rotating head on the side? Is that for 
repeating a word for spotting purposes? 

Mr. Hicks: We are stressing the im- 
portance of determining precisely the 
beginning and end of words. Visualizing 
devices such as modulation writing and 
combinations of magnetic stripes with 
photographic sound tracks do not always 
provide a definite indication of word 
endings visually, as most endings are low 
in level, high in frequency or a combina- 
tion of both. These sounds are very diffi- 
cult to see, and it is not unusual for the 
film editor to cut a track and lose an 
"ess" or a similar sound. He also often 
fails to see or hear low-level modulations 
which are a part of stage background 
sounds and leaves them in the track. 
These must then be further edited after 
they have been noticed during a rehearsal 
mixing session. 

With the dynamic scanner the film 
stands still while the head is rotated. The 
head reproduces only the words or parts 
of words which wrap the scanner drum, 
and film on the drum can be shifted by the 
editor until the word beginning or end 
is heard. After the exact spot is deter- 
mined the film is marked and cut in the 
usual way. The drum wrap allows from 
two to five words to be scanned, depending 
on the speed of the original speech. Scan- 
ning sound tracks in this manner helps 
the film editor considerably, especially 
when high-quality sound reproduction is 
combined with low machine noise. 



332 



September 1953 Journal of the SMPTE Vol. 61 



Automatic Film Splicer 



By A. V. JIROUGH 



An automatic film splicer is described in which an accurate join is obtained 
rapidly by the movement of two levers. The essential requirements of a 
modern splicer and their practical fulfillment are discussed. 



AERHAPS BECAUSE a splice is such a 
small thing very little attention has been 
given to the matter of splicing in the 
motion-picture industry. Improvements 
have been suggested from time to time 
in new patents and in the technical 
literature, but few have actually been 
put into effect. The result is that in 
spite of the vast progress made in the 
industry generally many of the same 
splicing problems that were experienced 
45 years ago are still being encountered 
today. The work of the SMPE Sub- 
committee on 16mm Film Splices 1 may 
be considered as the first serious discus- 
sion of the problems in this field with 
practical suggestions for improvement. 

Work was begun in 1945 to design a 
splicing machine which would cut, 
scrape and apply cement and appropriate 
pressure through a limited number of 
operations to ensure a perfect splice 

Presented on October 7, 1952, at the 
Society's Convention at Washington, D.G., 
by A. V. Jirouch, Cine Television Equip- 
ment (Overseas) Ltd., 317 Belle Grove 
Rd., Welling, Kent, England (paper 
read by Harry Teitelbaum, Hollywood 
Film Co., 5446 Carlton Way, Hollywood 
27, Calif.). 

(This paper was received October 7, 1952, 
and in revised form March 16, 1953.) 



without dependence on the skill of the 
operator. The first prototype was an 
electrically driven machine. 

Scraping. Different types of scraping 
tools, both static and rotating, were 
tested, the surface of each scrape was 
photographed and solubility tests made 
on different bases. During the progress 
of the work these tests gave good ex- 
perience with different mixtures of 
practically all known solvents. Samples 
of the splices made were stored and later 
gave valuable information with respect 
to ageing of different types of film base 
and durability of joins. 

As the number of samples increased 
it became more and more evident that 
the best results were achieved with tools 
removing the emulsion, substratum and 
skin of the base with one stroke, leaving 
the base rough, clean and open for 
penetration of solvents. It was not 
until six prototypes were built that it 
was possible to solve the question of 
uniform depth of scrape. This was 
achieved through a combination of 
specially shaped cutting tools, each one 
removing a part of the emulsion only 
(see Fig. 1 at E 41, 42). 

To determine the optimum width of 
join about 2500 different samples were 
used to show that joins ranging from 



September 1953 Journal of the SMPTE Vol. 61 



333 




Figure 1 



45 to 70 thousandths of an inch had the 
same tensile strength. It was not 
difficult to produce an overlap 20 
thousandths of an inch wide with a 
tensile strength greater than that of 
the base itself. It is not proposed at 
this time to discuss the different standards 
and widths of overlap used at present, 
but further data will be published on 
the durability of joins of different 
widths of overlap after completion of 
full-scale tests. 

The application of cement. Experience 
gained during the tests just mentioned 
showed that superior results were ob- 
tained when the cement was applied 
on the glossy surface of the base, instead 
of on the scraped area (see Fig. 3 at 
D, A 52, B 19). 

It was found that even better results 



could be obtained by applying the 
cement with a roller applicator of 
special surface and tension (see Fig. 3 
at 37, 38). The repeated passage of 
this roller across the surface of the film 
base not only applied the correct 
quantity of cement but also increased 
the penetration of solvents by agitation 
of the cement layer. In this way the 
base was dissolved to a sufficient depth 
to ensure a perfect weld. This principle 
of application has also solved the 
difficulty of anti-halo coating on several 
materials so that separate scraping of 
the coating is no longer required. 

Controlled pressure. Throughout the 
years various improvements have been 
made, but pressure control has become 
more and more important. Much 
attention was therefore given to the 



334 



September 1953 Journal of the SMPTE Vol. 61 




Figure 2 



cam-locking mechanism and the dia- 
gram (see Fig. 3 at C 28, 53, etc.) 
shows that the actual pressure is applied 
at the moment when the cam is locked. 

Suitable universal cement. The general 
use of safety base has introduced certain 
difficulties with regard to film cement. 
Cellulose acetate is a linear high polymer 
and displays the remarkable properties 
of a long-chain molecule, but the general 
solubility is somewhat more limited 
than that of cellulose nitrate. The fast 
mechanical operations of the machine 
permitted the use of low-viscosity solvents 
of balanced evaporation time. In this 
way no additional heating is required 
and the cement maintains its characteris- 
tics throughout the application and 
storage. 

Tests were made to prove that evapo- 
ration of solvents and loss of plasticizers 
from the base do not affect the durability 
of a splice made with this cement in 
conjunction with the mechanical proper- 



ties and speed of this machine. Several 
loops each with six joins were incu- 
bated by Kodak Limited, Harrow, 
England, and the effective ageing was 
observed by measuring the loss of 
solvents. All samples, even when pre- 
pared under different working condi- 
tions (room temperature and relative 
humidity), have shown greater tensile 
strength than the base itself. Seventeen 
of these samples were presented with 
the paper and it was found impossible 
to separate the splices by any means. 

Details of operation. It is well known 
that a good scrape with poor application 
of cement, uneven pressure or an un- 
satisfactory quality of cement will never 
give a reliable splice. And, of course, 
a poor splice is obtained with any 
combination of these factors. 

Recognizing the problems, all the 
above considerations were considered 
in designing the Robot Automatic Film 
Splicer which integrates the scraping, 



Jirouch: Automatic Film Splicer 



335 




Figure 3 



the application of cement and control of 
pressure, thereby providing the perfect 
splice on all types of film base presently 
in use. It is simple to operate and the 
influence of the human element is limited 
to the movement of the two levers only. 

The forward and backward movement 
of the rocking block (Fig. 1 at A) 
scrapes the emulsion to uniform depth 
and at the same time applies cement to 
the opposite part of the film. The up- 
and-down movement of the right sliding 
block (Fig. 3 at B) cuts both ends of the 
film squarely and applies the pressure. 

The machine is sturdily built, all 
important parts being made of stainless 
steel, ground and lapped, and both 
rocking and sliding movements are 
compensated for wear by spring-loaded 
tension (see Fig. 1 at A 1, A 2; Fig. 2 at 



20, 21, 22). The three-point register 
pins allow both negative and positive 
film to be spliced without adjustment 
being required. 

The cement tank holds sufficient 
cement for approximately 50 splices 
and a special adaptor can be fitted so 
that the machine can be operated all 
day without refilling. 

The scraping tools of high-speed steel 
will never require replacement and 
seldom require sharpening. Machines 
in practical use for 36 months far ex- 
ceeded the originally claimed 50,000 
operations without resharpening. 

The Robot II weighs 38 Ib and is 
equipped with a metal dust-proof cover 
(see Fig. 1 at 58, 59, 60) and can be 
operated anywhere without being at- 
tached to the bench (see Fig. 1 at 61, 



336 



September 1953 Journal of the SMPTE Vol. 61 




Fig. 4. The Robot II Splicer Mark V 35mm model 
56). Its dimensions are 7J- X 8f X References 



Acknowledgment. The author would 
like to express his appreciation to Messrs. 



1. Report of the Subcommittee on 16mm 
Film Splices, SMPE, 47: 1-11, July 
1946. 



Kodak Limited, Harrow, England, for 2. Pierre Jacquin, "Collures et colleuses," 



their cooperation and assistance in the 
preparation of samples. 



La Technique Cinematographique^ Sept. 
1948. 



Jirouch: Automatic Film Splicer 



337 



Revision PH22. 11 - 1953 

16mm Motion Picture Projection Reels 



THIS AMERICAN STANDARD was republished in the September 1952 Journal 
on pp. 233-237. Dimension S was incorrectly designated as an inside 
dimension in the drawing on p. 1 of the Standard (Journal p. 234). The 
complete Standard has been processed as a revision and the full Standard, 
ASA's PH22.11-1953 (officially a revision of PH22.11-1952), is published 
on the following pages. 



338 September 1953 Journal of tho SMPTE Vol. 61 



American Standard 
for 

16-Millimeter Motion Picture 
Projection Reels 


A5A 

Krt. V. S. Pal. Oj. 

PH22.11-1953 

Reviiion of 
Z22.IM94I 
and 
Z52.33-I945 


UDC 778.55 


Pag. 1 of 4 peg., 








hw 
w- 

ZZZ2 


- AT PERIPHER 

-AT CORE 

^AT SPINDLE 
HOLES 

> 


' ; OJ ; 




( /"~\T 

( Q ) <: 


) 


R 
f 


ENLARGED VIEW OF HOLE N 
FLANGE ON LEFT N SECTIONAL 
VIEW SHOWN ABOVE 


^ 
ZZZT 


'[gj> 




\^_ ^^X 




-s- 













ENLARGED VIEW OF HOLE IN 
FLANGE ON RIGHT IN SECTIONAL 
VJEW SHOWN ABOVE 


Table 


1 See page 3 for notes. 






Dimension 


Inches 


Millimeters 


A 


0.319 


-fO.OOO 
-0.003 


8 - 10 o$ 




B 


0.319 


+0.000 
0.003 


8 - 10 i8 






R 1 


0.790 


maximum 


20.06 maximum 






S 2 (including flared, 
rolled, or beveled 
edges, if any) 


0.962 


maximum 


24.43 maximum 






T (adjacent to 
spindle) 


0.027 
0.066 


minimum 
maximum 


0.69 minimum 
1.68 maximum 






U 


0.312 


0.016 


7.92 0.41 






V 




25 


+0.005 
-0.000 


3 ' 18 J2 






W, at periphery 3 




S60 


+0.045 
0.025 


1A7A + 1 ' 14 

16 ' 76 -0.64 






at core 4 


0.660 


0.010 


16.76 0.25 






at spindle holes 
Flange and core 
concentricity 5 


0.660 
0.031 


0.015 


16.76 0.38 
0.79 






Approved September 11, 1953, by the American Standards Association, Incorporated 
Sponsor: Society of Motion Picture and Television Engineers T,m,,..i Dim.i ciu.ific.tu>. 



Copyright, 1953, by American Standards Association, Inc.; reprinted by permission of the copyright holder. 

339 



American Standard 


ASA 

Ree. U. S. Pat. Off. 


for 




16-Millimeter Motion Picture 


PH22.1 1-1953 


Projection Reels 




Page 2 of 4 pages 


Table 2 




Capacity 


Dimension 


Inches 


Milli- 
meters 


Capacity 


Dimension 


Inches 


Milli- 
meters 






200 feet 6 


D, nominal 


5.000 


127.00 


1200 feet 


D, nominal 


12.250 


311.15 






(61 meters) 


maximum 


5.031 


127.79 


(366 meters) 


maximum 


12.250 


311.15 








minimum 


5.000 


127.00 




minimum 


12.125* 


307.98* 








C, nominal 


1.750 


44.45 




C, nominal 


4.875 


123.83 








maximum 


2.000* 


50.80* 




maximum 


4.875 


123.83 








minimum 


1.750 


44.45 




minimum 


4.625* 


117.48* 








Lateral 








Lateral 












runout/ 


0.057 


1.45 




runout, 7 


0.140 


3.56 








maximum 








maximum 










400 feet 6 


D, nominal 


7.000 


177.80 


1600 feet 


D, nominal 


13.750 


349.25 






(122 meters) 


maximum 


7.031 


178.59 


(488 meters) 


maximum 


14.000* 


355.60* 








minimum 


7.000 


177.80 




minimum 


13.750 


349.25 








C, nominal 


2.500 


63.50 




C, nominal 


4.875 


123.83 








maximum 


2.500 


63.50 




maximum 


4.875 


123.83 








minimum 


1.750* 


44.45* 




minimum 


4.625* 


117.48* 








Lateral 








Lateral 












runout, 7 


0.080 


2.03 




runout, 7 


0.160 


4.06 








maximum 








maximum 










800 feet 


D, nominal 


10.500 


266.70 


2000 feet 


D, nominal 


15.000 


381.00 






(244 meters) 


maximum 


10.531 


267.49 


(6 10 meters) 


maximum 


15.031 


381.79 








minimum 


10.500 


266.70 




minimum 


15.000 


381.00 








C, nominal 


4.875 


123.83 




C, nominal 


4.625 


117.48 








maximum 


4.875 


123.83 




maximum 


4.875 


123.83 








minimum 


4.500* 


114.30* 




minimum 


4.625 


117.48 








Lateral 








Lateral 












runout, 7 


0.120 


3.05 




runout, 7 


0.171 


4.34 








maximum 








maximum 








*When new reels are designed or when new tools are made for present 


reels, the cores and flanges should be made to conform/ as closely as prac- 


ticable, to the nominal values in the above table. It is hoped that in some 


future revision of this standard the asterisked values may be omitted. 



340 



American Standard Kt v s r 01 



for 

16-Millimeter Motion Picture 
Projection Reels 



PH22.11-1953 



Pag* 3 of 4 P o 8 t> 



Note 1 : The outer surfaces of the flanges shall be flat out to a diameter 
of at least 1 .250 inches. 

Note 2: Rivets or other fastening members shall not extend beyond the 
outside surfaces of the flanges more than 1 732 inch (0.79 millimeter) and 
shall not extend beyond the over-all thickness indicated by dimension S. 

Note 3: Except at embossings, rolled edges, and rounded corners, the 
limits shown here shall not be exceeded at the periphery of the flanges, 
nor at any other distance from the center of the reel. 

Note 4: If spring fingers are used to engage the edges of the film, dimen- 
sion W shall be measured between the fingers when they are pressed out- 
ward to the limit of their operating range. 

Note 5: This concentricity is with respect to the center line of 'the hole for 
the spindles. 

Note 6: This reel should not be used as a take-up reel on a sound projector 
unless there is special provision to keep the take-up tension within the 
desirable range of 1 Vz to 5 ounces. 

Note 7: Lateral runout is the maximum excursion of any point on the flange 
from the intended plane of rotation of that point when the reel is rotated 
on an accurate, tightly fitted shaft. 



341 



American Standard 
for 

16-Millimeter Motion Picture 
Projection Reels 


ASA 

Kri. V. S. Pal. Of. 

PH22.11-1953 



Pag.4of4pag.* 



Appendix 

(This Appendix is not a part of the American Standard for 16-Millimeter 
Motion Picture Projection Reels, PH22.11-1952.) 

Dimensions A and B were chosen to give sufficient clearance between the 
reels and the largest spindles normally used on 16-millimeter projectors. 
While some users prefer a square hole in both flanges for laboratory work, 
it is recommended that such reels be obtained on special order. If both flanges 
have square holes, and if the respective sides of the squares are parallel, the 
reel will not be suitable for use on some spindles. This is true if the spindle 
has a shoulder against which the outer flange is stopped for lateral position- 
ing of the reel. But the objection does not apply if the two squares are ori- 
ented so that their respective sides are at an angle. 

For regular projection, however, a reel with a round hole in one flange is 
generally preferred. With it the projectionist can tell at a glance whether or 
not the film needs rewinding. Furthermore, this type of reel helps the pro- 
jectionist place the film correctly on the projector and thread it so that the 
picture is properly oriented with respect to rights and lefts. 

The nominal value for W was chosen to provide proper lateral clearance 
for the film, which has a maximum width of 0.630 inch. Yet the channel is 
narrow enough so that the film cannot wander laterally too much as it is 
coiled; if the channel is too wide, it is likely to cause loose winding and ex- 
cessively large rolls. The tolerances for W vary. At the core they are least 
because it is possible to control the distance fairly easily in that zone. At the 
holes for the spindles they are somewhat larger to allow for slight buckling 
of the flanges between the core and the holes. At the periphery the toler- 
ances are still greater because it is difficult to maintain the distance with 
such accuracy. 

Minimum and maximum values for T, the thickness of the flanges, were 
chosen to permit the use of various materials. 

The opening in the corner of the square hole, to which dimensions U and 
V apply, is provided for the spindles of 35-millimeter rewinds, which are- 
used in some laboratories. 

D, the outside diameter of the flanges, was made as large as permitted 
by past practice in the design of projectors, containers for the reels, rewinds, 
and similar equipment. This was done so that the values of C could be macle 
as great as possible. Then there is less variation, throughout the projection 
of a roll, in the tension to which the film is subjected by the take-up mech- 
anism, especially if a constant-torque device is used. Thus it is necessary to 
keep the ratio of flange diameter to core diameter as small as possible, and 
also to eliminate as many small cores as possible. For the cores, rather widely 
separated limits (not intended to be manufacturing tolerances) are given in 
order to permit the use of current reels that are known to give satisfactory 
results. 



342 



74th Convention 



The Society's 74th Convention was just 
one month away as this issue of the Journal 
went to press; and it is therefore a very 
real pleasure to report that the Papers 
Program for this five-day affair that begins 
on Monday, October 5th, did not suffer 
seriously from the unseasonable summer. 
Skip Athey, Program Chairman, made the 
grade. He just beat our publication dead- 
line with an optimistic report on the success 
of papers procurement efforts. The titles 
so far assembled are in goodly number and, 
equally important, are closely tied to the 
more notable technical developments of 
recent months. 

Skip assures all readers that the follow- 
ing list of topics is firm and you will see 
for yourself that this schedule of events is 
as meaty and well balanced as any. Those 
who have handled similar program assign- 
ments in the past, however, will agree with 
Skip and his hard working assistants Bill 
Rivers, Joe Aiken, George Colburn, Gerry 
Graham, Charles Jantzen, Ralph Lovell, 
Glenn Matthews, Walt Tesch and John 
Waddell that credit for the resulting 
program is hardly recompense for effort ex- 
pended. 

Stereophonic sound reproduction and 
the projection of wide-screen pictures will 
be lead-off topics for the opening technical 
sessions on Monday, October 5th. The 
afternoon will be devoted to "basic prin- 
ciples," and the following morning, 
Tuesday, October 6th, there will be a 
group of papers on new sound and pro- 
jection equipment. In their commercial 
applications these processes represent the 
latest thing in motion pictures, so at- 
tendance at these sessions should be large. 
From present predictions it will include 
heavy representation from among Ameri- 
can and foreign theater owners. Monday 
evening will be reserved for the presentation 
of awards. 

This convention will have a session on 
high-speed photography, now set for 
Tuesday morning, to run concurrently 



jection equipment. The Tuesday after- 
noon session will be devoted to motion- 
picture laboratory equipment and prac- 
tices, and the evening session will include 
two groups of companion papers; one, on 
production of foreign language versions of 
American motion pictures, and the other 
on the related technicalities of magnetic 
striping. This session will be held at the 
Signal Corps Pictorial Center. 

To maintain a custom of long-standing 
there will be two paper sessions on Wed- 
nesday, October 7th, followed by a cock- 
tail party and banquet. The subject of the 
morning session on Wednesday will be 
television, with papers having mostly to do 
with films for television broadcasting. In 
the afternoon papers and discussion will 
center around theater television. The cock- 
tail party and banquet will be "informal" 
which somewhat illogically means "formal." 
In other words, if you have a dinner jacket, 
wear it ; if you don't well, do as you 
please, but by all means be comfortable 
and have a good time. 

Thursday morning, October 8th will be 
"open" so breakfast may be had at lunch 
time. Thereby we will observe once again 
a tradition of old, long hallowed in the 
hearts of Wednesday revelers, but for 
several seasons now sorely breached out of 
deference to matters technical. 

In the afternoon a general interest ses- 
sion will be held and on Thursday evening 
there will be an enlightening symposium on 
principles of 3-D. 

The session on Friday morning, October 
9th, will be devoted to the subject of new 
wide-screen techniques. Following the 
general session on Friday afternoon, 
Herbert Barnett will call for adjournment 
of the 74th Convention. 

All convention paper titles and authors 
will be listed in the Advance Program 
that is scheduled for early first-class mailing 
to all members within and without the 
United States. A few items of particular 
interest taken from that list are these: 



with the session on new sound and pro- 
"A 35mm Stereo Cine Camera" by Chester E. Beachell of National Film Board of Canada 
"Ferrite Core Heads for Magnetic Recording" by R. J. Youngquist and W. W. Wetzel 
of Minnesota Mining & Mfg. Co. 



343 



"Sensitometry of the Color Internegative Process" by C. R. Anderson, G. E. Osborne, 

F. A. Richey and W. L. Swift of Eastman Kodak Co. 
"Stereoscopic Perceptions of Size, Shape, Distance and Direction" by D. L. Mac Adam 

of Eastman Kodak Co. 
"An Auxiliary Multitrack Magnetic Sound Reproducer" by C. C. Davis and H. A. 

Manley of Westrex Corp. 
"A Film-Pulled Theater-Type Magnetic Sound Reproducer for Use With Multitrack 

Films" by J. D. Phyfe and C. E. Hittle of Radio Corporation of America 
"A New Vidicon Tube for Film Pickup" by R. G. Newhauser of Radio Corporation of 

America 



There is more to a convention than 
papers for which the chain of command in- 
cludes Norwood Simmons, Editorial Vice- 
President, and Bill Rivers, Chairman of 
the Papers Committee. Jack Servies, 
Convention Vice-President is top manager 
of the many other convention matters 
including luncheon, banquet and the so- 
essential local arrangements. His work is 
always well delegated and for 74th Conven- 
tion these are his assistants : 
Local Arrangements 

Chairman W. H. Offenhauser, Jr. 
Vice-Chairman R. C. Holslag 
Vice-Chairman S. L. Silverman 



Registration J. C. Naughton 
Hospitality Marie Douglass 
Projection Charles Muller 
Public Address George Costello and 

Dominick Lopez 

Hotel & Transportation L. E. Jones 
Luncheon & Banquet Emerson Yorke, 

J. B. McCullough and J. G. Stott 
Membership A. R. Gallo 
Motion Pictures V. J. Gilcher 
Publicity Harold Desfor and Leonard 

Bidwell 



Current Literature 



The Editors present for convenient reference a list of articles dealing with subjects cognate to motion 
picture engineering published in a number of selected journals. Photostatic or microfilm copies of 
articles in magazines that are available may be obtained from The Library of Congress, Washington, 
B.C., or from the New York Public Library, New York, N. Y., at prevailing rates. 



American Cinematographer 

vol. 34, July 1953 
Single-film, Single-projector 3-D (p. 319) N- 

Cohen 

3-D Television (p. 320) 
Vistarama Wide-Screen System for 16mm 

Movies (p. 326) H. A. Lightman 

Bell System Technical Journal 

vol. 32, July 1953 

Television Terminals (p. 915) J. W. Rieke and 
R. S. Graham 

Electronics 

vol. 26, Aug. 1953 
Standards Converter for International TV (p. 

144) A. V. Lord 
Design of Export Television Receivers (p. 174) 

G. D. Hulst 

Focus 

vol. 38, no. 13, June 27, 1953 
De Nieuwe Philips Televisie-camera (p. 267) 



Ideal Kinema (Supplement to Kinematograph 
Weekly) 

vol. 19, July 9, 1953 
Carbons to Light the Wide Screen (p. 5) R. H. 

Cricks 

The Equipment Behind CinemaScope (p. 9) 
The Mathematics of Wide Screen (p. 17) 

Proceedings of the I.R.E. 

vol. 41, July 1953 
Colorimetry in Color Television (p. 838) F. J. 

Bingley 
The PDF Chromatron A Single or Multi-Gun 

Tri-Color Cathode-Ray Tube (p. 851) R. 

Dressier 

vol. 41, Aug. 1953 

A Subjective Study of Color Synchronization 
Performance (p. 979) M. I. Burgett, Jr. 

International Photographer 

vol. 25, Aug. 1953 
Editing 3-D (p. 5) R. Fehr 
Processing Color Film, Pt. 2 (p. 22) G. Ashton 
Graphic Representation of Various 3-D and 
Wide Screen Processes (p. 23) 



344 



International Projectionist 

vol. 28, July 1953 

Round-Up of the Wide-Screen Process (p. 5) 
Visibility Factors in Projection, Pt. 3 Color 

and Nature of Projection Light (p. 11) /?. A. 

Mitchell 
Projector Carbons for New Motion Picture 

Systems (p. 14) F. P. Holloway, R. M. Bushong 

and W, W. Loner 

Kino-Technik 

vol. 7, July 1953 
Der heutige Stand der Filmwissenschaft in 

Deutschland (p. 184) E. Feldmann 
Raumfilm mit Farbe Wirklichkeitsnah (p. 

186) H. N. O'Leary 
Moglichkeiten und Grenze der Farbkorrektur 

(p. 188) A. Kocks 
Storungen bei der Vorfiihrung von Tonfilmen 

(p. 193) H. Tummel 
Die Moglichkeiten zur Vertonung von Amateur- 

filmen (p. 194) F. Frese 
Cameflex-Fernsehkamera Modell "T" 16mm 

(p. 198) 

Motion Picture Herald (Better Theatres 
Section) 

vol. 191, July 4, 1953 

Crisis in Sound, 1953 (p. 11) 

Precision Requirements of 3-D: Shutter Syn- 
chronization, Interlocking and Alignment 
(p. 15) G. Gagliardi 

vol. 191, Aug. 1, 1953 

Projection Factors of Wide-Screen Installation 
(p. 8) G. Gagliardi 



New Carbons for the New Projection System 
(p. 31) F. P. Holloway, R. M. Bushong and 
W. W. Lozicr 

Radio & Television News 

vol. 50, no. 2, Aug. 1953 
Film for TV (p. 35) H. J. Seitz 
Troubleshooting TV High-voltage Supplies (p. 

48) M. H. Lowe 
Know Your 1953 Emerson TV Receivers (p. 

52) B. Kutny 

R & TV News (Radio-Electronic Eng. Sec.) 

vol. 50, no. 2, Aug. 1953 

Pressure 1 Testing of TV Tubes (p. 8) G. D. 
Ostrander 

RCA Review 

vol. 14, June 1953 
Optimum Utilization of the Radio Frequency 

Channel for Color Television (p. 133) R. D. 

Kell and A. C. Schroeder 
Principles and Development of Color Television 

Systems (p. 144) G. H. Brown and D. G. C. 

Luck 
Color Television Signal Receiver Demodulators 

(p. 205) D. H. Pritchard and R. N. Rhodes 
Colorimetric Analysis of RCA Color Television 

System (p. 227) D. W. Epstein 

TV & Radio Engineering 

vol. 23, no. 3, June-July 1953 
Microwave Units for TV Services (p. 14) S. 

Topal and W. T. Beers 
16-mm Projector for Television (p. 17) 
Color TV Experimental Equipment (p. 19) 
Low Cost TV Camera (p. 28) 



Book Reviews 



Photoelectric Tubes 

By A. Sommer. Published (late 1952) by 
John Wiley & Sons, 440 Fourth Ave., 
New York 16. 118 pp. 27 diagrams. 
4 X 6 in. $1.90. 

It would seem improbable that this little 
volume could treat the emissive type of 
photocell from the basis for the photo- 
electric effect in Einstein's and Fermi's 
theories, through physical aspects, chemical 
nature of complex cathodes, manufacturing 
techniques, spectral response and engineer- 
ing application. Yet it does, and clearly. 

The chapter headings give further clues 
as to what is to be found in the book: 
I, Historical Introduction; II, Theories 
of Photoelectric Emission; III, Photo- 
electric Cathodes; IV, Matching of Light 
Sources and Photocathodes ; V, Vacuum 



Photocells; VI, Gasfilled Photocells; VII, 
Multiplier Photocells; and VIII, Applica- 
tions of Photocells. 

Material is included on the direct 
applications to sound motion pictures and 
television, which serves to relate all other 
material to the chief interest of the readers 
of this Journal. 

Dr. Sommer is of the EMI Research 
Laboratories in England, but it appears 
that the British electrons behave exactly 
the same as do the American ones. Fur- 
thermore, American tubes are discussed. 
A convenient table of photocathode types 
for a dozen tubes and a bibliography of 69 
entries to the scientific and engineering 
literature of both the United States and 
Europe are included. Harry R. Lubcke, 
Registered Patent Agent, 2443 Greston 
Way, Hollywood 28, Calif. 



345 



Photography, Its Materials 
and Processes, 5th ed. 

By C. B. Neblette and 14 collaborators. 
Published (1952) by C. Van Nostrand, 
250 Fourth Ave., New York 3. vii + 
490 pp. + 10 pp. index. 350 illus. 
7 X 9 in. $10.00. 

Ed. Note: We have been unable to get 
a review long ago promised for the 
Journal. Rather than let this book go 
unnoticed, we have obtained permission 
to reprint the following review by Dr. 
O. W. Richards, American Optical Co., 
Stamford, Conn., from the Journal of the 
Biological Photographic Assn., 20: 121, 
Aug. 1952. 

For twenty-five years this has been a 
standard book for photographers. Now 
it is encyclopedic and much of it has been 
written by experts including our Lloyd 
Varden. This volume of 33 chapters is 
primarily on materials and their use, shows 
the increasing technical progress in the 
field. Gone are chapters on enlarging 
and lantern slide making. Instead the 
emphasis is now on color. With the 
exception of a few chapters (including 
Varden's) the rest of the book is made 
from reference material up to about 1945 
or 1947, so that some of it is already out 
of date. The section on electronic flash, 
for example, does not mention the new 
smaller tubes and the convenient voltage 
doubler circuits. For a student textbook, 
that it still states that it is, a chapter on the 
essentials of a good picture would add to 
the usefulness of the book. While it will 
probably be rather difficult reading for 
the beginner, the advanced photographer 
will find most of his questions answered 
and no department should be without this 
remarkably complete reference book. 
O.W.R. 



Television Scripts for 
Staging and Study 

By Rudy Bretz and Edward Stasheff. 
Published (1953) by A. A. Wyn, 23 W. 
47 St., New York 36. 328 pp. + 4 pp. 
index. Numerous illus. $4.95. 

An earlier book, The Television Program 
by the same authors, was reviewed for 
this Journal with the conclusion that it 



did all that a book could do for those 
learning television production. The earlier 
reviewer emphasized the values of actual 
experience and observation. These authors 
are aware of those values for they have 
extensive experience teaching where com- 
plete equipment was a part of the school. 
They are both still teaching, between or 
along with other stints. And while their 
first book goes on being adopted as the 
text in additional dozens of schools and 
universities, this book comes as an addi- 
tional tool for the teacher and student 
director or producer. 

Considering that, in this JournaVs 
modest fan mail, the commonest specific 
reference has been to articles by Author 
Bretz, we need not here attempt to assess 
in any detail the parts of this book. Intro- 
ductory to the second and third parts of 
the book, which are "The Simpler For- 
mats" and "Full-Length Scripts," is the 
friend-of-the-engineer part, "Creative 
Camera Techniques" which includes chap- 
ters on pictorial composition (control over 
subject) and shots in sequence (cutting 
techniques). We suggest that student 
and learning directors who become aware 
of what can and cannot be done with their 
studio facilities are important contributors 
to a well-engineered picture on the air. 
V.A. 



Technical Reporting 

By Joseph N. Ulman, Jr. Published 
(1952) by Henry Holt, 383 Madison 
Ave., New York 17. i-xiv -f 284 pp. + 
5 pp. index. $4.75. 

This is a good book for the many who 
need such a book. We are in favor of all 
such books, just as all busy editors are 
against the crimes which writers attempt 
against the general welfare of the readers. 

Technical Reporting is shorter than many 
books telling engineers how to write 
because the author has followed his own 
advice: "You owe it to your reader to 
make your meaning immediately clear 
with a minimum of study on his part." 

The author does not have the futile 
ambition to make grammarians out of 
technical men. He has prepared a text 
which is worthy of study and recurrent 
browsing and is useful in a modest way as 
a reference. He lists other books which 



346 



serve standard reference purposes. This 
is not an officious apologia for a volume 
of fine points. It is an efficient presenta- 
tion of common-sense bases for effective 
technical writing. The Table of Contents 
is a pleasure to read and use for it is fully 
but not ponderously supported by the 
text. V.A. 

Television Factbook, No. 17 
July 15, 1953 

Published (July 15, 1953) by Radio News 
Bureau, Wyatt Bldg., Washington 5, D.C. 
356 pp. incl. folding wall map in color. 
8 \ X 11 in. $3.00. 

The new 1953 midyear edition of this 
vast compendium of facts about the tele- 
vision world has a number of new depart- 
ments, including sets-in-use by states and 
counties (both NBC Research's TV-&- 
radio count and CBS's TV count); the 
.1. Walter Thompson Co. study of house- 
holds and TV sets in "First 312 Markets 
of the U.S."; directory of TV stations in 
foreign countries; tables showing annual 
volume of advertising in U.S. by media, 
1946-52; tabulation of financial data on 
leading TV-radio manufacturers; and 
first detailed listings of tuner, converter 
and receiving antenna manufacturers. 

The Factbook provides personnel listings, 
facilities and ownership data and rate 
card digests of all TV networks (including 
the new Canadian), and of the 227 U.S. 
stations now operating or due to be in 
operation by August 1, and tabulations of 
new-station applications pending and out- 
standing construction permits. 

Among other features are directories of 
program sources, FCC personnel, attorneys, 
engineers, consultants, trade associations, 
unions, publications, etc. ; listings of com- 
munity antenna systems, theaters equipped 
for TV, and directories of manufacturers 
of receivers, tubes, transmitters, studio 
equipment, etc. ; channel allocation tables ; 
FCC priority lists; network TV-radio 
billings, 1949-53; and FCC reports on 
revenues, expenses and earnings of TV 
networks and stations, 1946-52. 



American Cinematographer Hand 
Book and Reference Guide 

By Jackson J. Rose. Published (1953) by 
American Cinematographer Hand Book, 
458 So. Doheny Dr., Beverly Hills, Calif. 
8th ed., 328 pp., incl. advts. 4 X 6$ in. 
Flexible binding. Price $5.00. 

The Eighth Edition of this standard 
reference guide has the charts, tabulations, 
formulas and indexes with which users of 
previous editions will be familiar. This 
edition has been announced as also cover- 
ing these new features: Cinerama, tele- 
vision photography, zoom lenses, latensi- 
fication, underwater photography, back- 
ground projection, T-stops, Ansco Color 
Negative-Positive Process, Eastman Color 
Negative and Print Film, Du Pont Color 
Release Positive Film and many new charts 
and tables. 

Workers in motion-picture and still 
photography and in television will find 
this still a very useful reference as last 
described when the seventh edition was 
reviewed in September 1950 in the 
Journal. V.A. 



"Research Film" 

The Research Film Committee of the 
International Scientific Film Association 
announces a new bulletin, Research Film, 
designed as a vehicle for the international 
exchange of information in the field of 
its title. The tri-lingual publication is 
under the editorship of Dr. G. Wolf of 
Gottingen and Jean Dragesco of Paris. 
Notices appear in French, German and 
English; articles are published in their 
original language. Reports on American 
work are sought. Further information 
can be obtained from the chairman of the 
Research Film Committee, Dr. G. Wolf, 
Institut fur Film und Bild Abt. Hoch- 
schule und Forschung, Bunsenstrasse 10, 
Gottingen, Germany. 



SMPTE Officers and Committees: The roster of Society Officers and the 
Committee Chairmen and Members were published in the April Journal. 



347 



New Members 



The following members have been added to the Society's rolls since those last published. The 
designations of grades are the same as those used in the 1952 MEMBERSHIP DIRECTORY. 



Honorary (H) 



Fellow (F) 



Active (M) 



Associate (A) 



Student (S) 



Austin, Otto, Motion-Picture Producer, Austin 
Productions, Inc., 232 f North Main St., 
Lima, Ohio. (A) 

Ayling, Russell J., Electrical Engineer, Strong 
Electric Corp., 87 City Park Ave., Toledo, 
Ohio. (M) 

Bass, Vincent F., Cinema togra pher, Photog- 
rapher. Mail: 564 Rutland Ave., San 
Jose 28, Calif. (A) 

Becker, Sherwin H., Editor, Douglas Produc- 
tions. Mail: 5214^ South Drexel Blvd., 
Chicago 15, 111. (A) 

Berliner, Oliver, Audio-Video Consulting, 
Oberline, Ltd., 6411 Hollywood Blvd., Holly- 
wood 28, Calif. (A) 

Bogardus, John O., Motion-Picture Projection- 
ist, W. S. Butterfield Theatres, Inc. Mail: 
344 Coldbrook, N.E., Grand Rapids 5, 
Mich. (M) 

Carlson, George, Television Supervisor, KSTP- 
TV, Inc., St. Paul, Minn. (M) 

Constable, James M., Producer-Director, Wild- 
ing Picture Productions, Inc., 1345 Argyle 
St., Chicago, 111. (M) 

Di Lonardo, Hugh, Motion-Picture and 
Television Films Instructor, Television Work- 
shop. Mail: 75 W. 97 St., New York, 
N.Y. (A) 

Druz, Walter S., Research Engineer, Zenith 
Radio Corp. Mail: 228 South Center St., 
Bensenville, 111. (M) 

Dyer, Robert W., Studio Manager, Motion 
Picture Advertising Service Co., Inc., 1032 
Carondelet St., New Orleans, La. (M) 

Gaines, Albert, Motion-Picture Laboratory 
Technician, DeLuxe Laboratories. Mail: 
c/o Greenwald, 3210 Perry Ave., Bronx, 
N.Y. (A) 

Grodin, Burton, President, University Camera 
Exchange. Mail: 3678 Crest Rd., Wantagh, 
Long Island, N.Y. (M) 

Herrick, Kenneth P., Field Engineer, Radio 
Corporation of America. Mail: 2516 Fulton 
St., Toledo, Ohio. (A) 

Hughes, Tom F., Motion-Picture Production 
Supervisor, American Airlines, Inc. Mail: 
44 Shadyside Ave., Port Washington, N.Y. 
(A) 

linns, Henry O., Color Camera Technician, 
Technicolor Motion Picture Corp. Mail: 
3180 Vista Del Mar, Glendale 8, Calif. (A) 

Jarrett, A. W., Motion-Picture Cameraman, 
KOB-TV. Mail: 1934 Meadow View Rd., 
Albuquerque 1, N.M. (A) 



Jensen, Peter Axel, Research Trainee, Techni- 
color Motion Picture Corp., Box 16-547, 
Hollywood 38, Calif. (A) 

Keilhack, Francis W., Representative and 
Technical Adviser, Drive-In Theatre Manu- 
facturing Co., 505 W. Ninth St., Kansas City, 
Mo. (M) 

Koerner, Allan M., Eastman Kodak Co., Kodak 
Park, Bldg. 65, Rochester, N.Y. (A) 

Krtous, George F., Engineer, De Vry Corp. 
Mail: 2547 South Harding Ave., Chicago 23, 
111. (M) 

Laby, Lawrence M., Production Manager, 
Natural Vision Theatre Equipment Corp. 
Mail: 5461 Tampa Ave., Tarzana, Calif. 
(A) 

Langendorf, Matthew P., Engineer, Ampro 
Corp. Mail: 3512 West Lemoyne St., 
Chicago 51, 111. (M) 

Lester, F. C., Broadcast Engineer, Mid-Conti- 
nent Broadcasting Co., KOWH. Mail: 3514 
N. 61 St., Omaha, Nebr. (A) 

Lovell, Herman J., Chief Engineer, WKY 
Radiophone Co., 500 East Britton Rd., 
Oklahoma City, Okla. (M) 

Lucas, James W., Aircraft and Mechanical 
Engineer, The Stephen-Douglas Co. Mail: 
311 South Amalfi Dr., Santa Monica, Calif. 
(A) 

Mavrides, William, Film Editor and Film 
Librarian, WAKR-TV, First National Tower, 
Akron, Ohio. (A) 

Merrifield, Robert C., Television Set Lighting 
Technician. KLAC-TV. Mail: 220 South 
Hoover St., Los Angeles 4, Calif. (A) 

Mirarchi, Michael R., Photographic Tech- 
nician, Signal Corps Engineering Labora- 
tories. Mail: 141 Atlantic Ave., Long 
Branch, N.J. (A) 

Navarro, Jose C , Cinematographer, Television 
Technical Director, DZAQ-TV. Mail: 1230 
Oroguieta, Sta. Cruz, Manila, Philippines. 
(A) 

Newman, Robert P., Film Executive, Telepix 
Corp., 1515 North Western Ave., Hollywood, 
Calif. (M) 

Reid, Seerley, Chief, Visual Education Service, 
U.S. Office of Education, Washington 25, 
D.C. (A) 

Reynolds, Ernest M., Mo lion-Picture and Slide- 
Film Producer. Mail: 165 E. 191 St., 
Cleveland 19, Ohio. (M) 

Richartz, Paul, Design Engineer, Bell & Howell 
Co. Mail: 87 Orchid Rd., Levittown, 
Long Island, N.Y. (M) 



348 



Richter, A. A., Service Engineer, Army and Air 
Force Motion Picture Service. Mail: 4927 
Imlay Ave., Culver City, Calif. (A) 

Rolph, Donald B., Motion-Picture Sound Re- 
cording. Mail: 15450 Pepper La., Los 
Gatos, Calif. (A) 

Schley, Norman E., Cameraman, Director, 
Picturelogue, Inc., 204 Wisconsin Ave., 
Waukesha, VVis. (M) 

Sherburne, Edward G., Jr., Navy Special 
Devices Center. Mail: 10 Clent Rd., Great 
Neck, N.Y. (M) 

Stadig, Sidney V., TV Technical Supervisor, 
Westinghouse Radio Stations, Inc. Mail: 
86 Spring St., Lexington, Mass. (M) 

Walls, Fred M., Sound Engineer. Mail: 827 
Wayne, Topeka, Kan. (M) 



Washick, Walter J., Design Draftsman, Techni- 
color Motion Picture Corp. Mail: 1931 
Lietz Ave., Burbank, Calif. (A) 

Wilson, Jimmy, Producer and Photographer, 
Jimmy Wilson Studios, 724 S. 29 St., Birming- 
ham, Ala. (M) 

Winter, A. Roane, Assistant Sound Engineer, 
Missions Visualized, Inc. Mail: 1034 East 
Walnut Ave., Burbank, Calif. (A) 

Wohler, Johann F., Optical Engineer, A. G. 
Optical Co., 5574 Northwest Highway, 
Chicago, 111. (M) 



CHANGES IN GRADE 

Clarke, Anthony, (S) to (A) 

F u Ik- r ton, Richard D., (A) to (M) 

Tinker, Clarence J., (A) to (M) 



Chemical Corner 



Edited by Irving M. Ewig for the Society's Laboratory Practice Committee. Suggestions should 
be sent to Society headquarters marked for the attention of Mr. Ewig. Neither the Society nor the 
Editor assumes any responsibility for the validity of the statements contained in this column. They 
are intended as suggestions for further investigation by interested persons. 



Saving Shipping Costs The laboratory 
plagued by high 

chemical shipping costs ought to consider 
the substitution of sodium thiosulfate- 
anhydrous for the crystalline hypo which 
contains 35% water. The ultimate cost 
of hypo can be determined on the basis 
that 65 Ib of the anhydrous variety is 
equal to 100 Ib of the common crystalline 
type. The use of anhydrous sodium car- 
bonate (soda ash) can be substituted 
effectively for sodium carbonate-mono- 
hydrate on 85:100 Ib basis. Also soda 
ash is stocked at various shipping fronts 
throughout the country. 

A Universal Adhesive A new adhesive 
that may prove 

of interest to the motion-picture and 
television industries can be used to adhere 
felt, cork, sponge, solid rubber, etc., to a 
variety of surfaces. The manufacturer, 
The Rubber Latex Go. of America, 110 
Delawanna Ave., Clifton, N.J., claims 
that their adhesive is the most universal 



one developed in recent years. The 
product, designated Rula 181-3, can be 
applied to rolls or sheets like paint and 
allowed to dry. Parts cut from the coated 
rolls or sheets can be shipped or laid aside, 
and upon being remoistened with a pe- 
troleum-type solvent or cleaning fluid, 
may be pressed into place on any surface 
such as steel, wood, paint, plaster, paper, 
glass, ceramics, etc., and become per- 
manently adhered after an extremely 
short drying period. The adhesive may 
also be used in the conventional manner 
by applying and using while still wet. 



This May Be a 
Good Film Cement 



A cement which has 
exceptionally good 
adhesive properties 

for cellulose acetate is called C D Cement 
#150. It is colorless, fast-acting and 
produces an unusually strong bond. This 
product may have possibilities as a good 
film cement and anyone interested should 
consult the manufacturer, The Chemical 
Development Corp., Danvers, Mass. 



349 



New Products 



Further information about these items can be obtained direct from the addresses given. As in the 
case of technical papers, the Society is not responsible for manufacturers' statements, and publica- 
tion of these items does not constitute endorsement of the products. 




The Bowline Screen Frame is made of 
steel tubing, reportedly can be installed 
in less than an hour without special 
skills, and weighs about a pound for each 
square foot of screen surface for a 
20 X 30 ft screen, about 600 Ib. The 
frame's adjustability is described: height, 
adjustable so that any aspect ratio can 



be obtained; tilt, degree of tilt easily 
set; curve, with radius laid off on the floor, 
the frame is set directly over the position 
line and formed. Both the tilt and the 
curvature can be varied or the frame can 
be adjusted to .provide a flat screen. It 
is manufactured by H. R. Mitchell and 
Co., Hartsell, Ala. 



SMPTE Lapel Pins 



The Society has available for mailing its gold and blue enamel lapel pin, with a screw 
back. The pin is a ? 2 -'m. reproduction of the Society symbol the film, sprocket and 
television tube which appears on the Journal cover. The price of the pin is $4.00, 
including Federal Tax; in New York City, add 3% sales tax. 



350 




The Spectra Color Densitometer, manu- 
factured by Photo Research Corp., 127 
West Alameda Ave., Burbank, Calif., 
measures black-and-white (both print and 
visual), color and sound track by infrared 
phototube. The left head is used for 
black-and-white and color; the right head 
for sound track. A special interference 
filter can be used to limit the sensitivity 
to a narrow band at the peak region of 



infrared sensitivity. Separate zero adjust- 
ments for the blue, green and red color 
positions permit readings to be taken of a 
given patch without moving the film. 
The left head is always ready for black- 
and-white and color readings and the right 
head for sound-track readings. Change 
from one to the other is made by a switch. 
Both heads have special illuminated disks 
surrounding the apertures to facilitate 
finding desired areas. 



Employment Service 



These notices are published for the service of the membership and the field. They are inserted for 
three months, and there is no charge to the member. 



Positions Wanted 

Experienced motion-picture production 
man desires connection with film company 
as producer-director or production man- 
ager. During past 12 yrs. experience 
includes directing, photographing, editing, 
recording and processing half-million feet 
finished film, including educational films, 
industrials, TV spots, package shows for 
TV and experimental films. University 
graduate, married, twenty-nine years old; 
good references. Locate anywhere conti- 
nental U.S. Write Victor Duncan, 8715 
Rexford Drive, Dallas 9, Tex. 

Film Production /Use: Experienced in 
writing, directing, editing, photography; 
currently in charge of public relations, 



sales and training film production for 
industrial organization. Solid film and 
TV background, capable administrator, 
creative ability, degree. References and 
resume upon request. Write FPF, Room 
704, 342 Madison Ave.. New York 17, 
N.Y. 

Position Available 

Wanted: Optical Engineer for permanent 
position with manufacturer of a wide 
variety of optics including camera objec- 
tives, projector, microscope and telescope 
optics, etc. Position involves design, de- 
velopment and production engineering. 
Send resume of training and experience to 
Simpson Optical Mfg. Co., 3200 W. Carroll 
Ave., Chicago 24, 111. 



351 



Department of Defense Symposium on Magnetic Recording 

A full and worth-while program has been E. W. D'Arcy will give a paper on 

arranged to be held on October 12 and 13 "Calibrated Recordings and Measurement 

in the Department of Interior Auditorium, Techniques," reviewing the Society's posi- 

Washington, D.G. The organizers plan l n , , , 

to avoid a rehash of basic theory and intend tlon M reflec u ted u b j P r ^ ess * ** SU ^ 

the symposium to be a meeting ground committee which he heads; and John G. 

where different branches of the magnetic Frayne is scheduled to present a paper on 

recording industry may exchange views "Components and Mechanical Consider a- 

for their general benefit, as well as for the tions." 

benefit of the Department of Defense. SMpTE esentative for the Armed 
Individuals from industry engaged in 

magnetic recording development are in- Forces Symposium has been Joseph E. 
vited to attend. There is no fee for Aiken, Naval Photographic Center, Ana- 
registration, costia, D.C. 



Meetings 



The Royal Photographic Society's Centenary, International Conference on the Science 
and Applications of Photography, Sept. 19-25, London, England 

National Electronics Conference, 9th Annual Conference, Sept. 28-30, Hotel Sherman, 

Chicago 

74th Semiannual Convention of the SMPTE, Oct. 5-9, Hotel Statler, New York 
Audio Engineering Society, Fifth Annual Convention, Oct. 14-17, Hotel New Yorker, 

New York, N.Y. 

Society of Motion Picture and Television Engineers, Central Section Meeting, Oct. 1 5 

(tentative), Chicago, 111. 

Theatre Equipment and Supply Manufacturers' Association Convention (in conjunction 

with Theatre Equipment Dealers' Association and Theatre Owners of America), 

Oct. 31-Nov. 4, Conrad Hilton Hotel, Chicago, 111. 

Theatre Owners of America, Annual Convention and Trade Show, Nov. 1-5, Chicago, 111. 
National Electrical Manufacturers Association, Nov. 9-12, Haddon Hall Hotel, Atlantic 

City, N.J. 

Society of Motion Picture and Television Engineers, Central Section Meeting, Nov. 12 

(tentative), Chicago 111. 

The American Society of Mechanical Engineers, Annual Meeting, Nov. 29-Dec. 4, 

Statler Hotel, N.Y. 

Society of Motion Picture and Television Engineers, Central Section Meeting, Dec. 10 

(tentative), Chicago, 111. 

American Institute of Electrical Engineers, Winter General Meeting, Jan. 18-22, 1954, 

New York 

National Electrical Manufacturers Assn., Mar. 8-11, 1954, Edgewater Beach Hotel, 

Chicago, 111. 

Radio Engineering Show and I.R.E. National Convention, Mar. 22-25, 1954, Hotel 

Waldorf Astoria, New York 

Optical Society of America, Mar. 25-27, 1954, New York 

75th Semiannual Convention of the SMPTE, May 3-7, 1954, Hotel Statler, Washington 
Acoustical Society of America, June 22-26, 1 954, Hotel Statler, New York 
76th Semiannual Convention of the SMPTE, Oct. 18-22, 1954 (next year), Ambassador 

Hotel, Los Angeles 

77th Semiannual Convention of the SMPTE, Apr. 17-22, 1955, Drake Hotel, Chicago 
78th Semiannual Convention of the SMPTE, Oct. 3-7, 1955, Lake Placid Club, Essex 

County, N.Y. 

352 



Increasing the Efficiency of 
Television Station Film Operation 



By R. A. ISBERG 



Techniques have been developed in the scheduling of film programs and the 
splicing of films which reduce the technical manpower required for operations. 
By utilizing oversize reels and remote control of the projection equipment, two 
men can easily handle audio and video control and also be responsible for 
normally unattended film projection equipment. Practical techniques of film 
splicing and editing are also described. 



M, 



.ORE than half of the average tele- 
vision station's program time is generally 
supplied by 16mm film. Film is re- 
quired from sign-on to sign-off time 
which covers a period of from ten to 
seventeen hours per day. During major 
portions of the program schedule the 
entire operation usually depends upon 
film with no live studio participation. 
In some of the smaller stations the entire 
program schedule is transmitted from 
film and network microwave, if avail- 
able. 

From the standpoint of economy, it is 
desirable to have the studio, offices and 
transmitter at one location, but in many 
areas propagation considerations require 
that the transmitter be located on a high 
hill or mountain. This almost invari- 



Presented on April 28, 1953, at the Soci- 
ety's Convention at Los Angeles by R. A. 
Isberg, Consulting Television Engineer, 
2001 Barbara Dr., Palo Alto, Calif. 
(This paper was received first on May 11, 
1953, and in revised form on August 28, 
1953.) 



ably results in separate studio and trans- 
mitter locations with a correspondingly 
increased technical staff. 

After careful consideration of operating 
costs and program plans, some television 
stations have installed their film-projec- 
tion facilities at their transmitter and 
their live studio facilities at a downtown 
location. This permits film operation 
at any time and live telecasting can be 
confined to times when a studio crew is 
available. However, it creates a minor 
film-transportation and make-up prob- 
lem, and in some ways complicates the 
integration of film with live programs, 
since the film-camera monitors cannot be 
economically duplicated at the studio. 
This latter objection applies particularly 
to the preview of visual effects by the 
producer or director at the studio prior 
to their use in an integrated live and 
film program, but it is possible to inte- 
grate films and live programs very satis- 
factorily without the studio preview 
facilities by coordinating the operations 
through a private-line telephone. If 



October 1953 Journal of the SMPTE Vol. 61 



447 



film-projection facilities are provided at 
both the transmitter and the studio the 
remaining problem is only the film make- 
up and transportation for the portion of 
the day when film is utilized exclusively 
from the transmitter. 

Initial Planning Considerations 

In planning a television station and 
determining its staff requirements it is 
necessary to define the responsibilities of 
each staff member and to select and lay 
out the facilities so that the contemplated 
program schedule can be fulfilled. The 
small station's operating requirements 
are usually quite simple and can be ade- 
quately handled by combining some of 
the operating responsibilities to save 
manpower. In some instances, the 
purchase of additional equipment will 
reduce the staff requirements, and a 
choice may be made between spending a 
salary in a short period of time or amor- 
tizing an equivalent investment in equip- 
ment over a much longer period. 

Inefficient initial planning will lead to 
difficulty in the later modification of ex- 
isting operating practices because of 
possible opposition on the part of labor 
unions or fear on the part of the employ- 
ees that the standard of operation may 
suffer. A new organization entering the 
television field is not bound by conven- 
tion or contract with respect to the 
duties of its employees and it is therefore 
free to establish its business as it chooses. 
The employees will be as anxious as the 
management to create a new business 
which will profit and with which they 
will be proud to be associated, but they 
will look with alarm upon any attempt to 
reduce personnel requirements through 
the modification of an existing plant. 

Analysis of Operating Functions 

The requirements for the various tech- 
nical operating functions in a television 
station are easily analyzed. The audio 
levels of sound on film programs have 
been previously monitored and the same 
is true of programs originating by a net- 




work or at a remote or studio broadcast. 
Therefore, except for program switching 
and initial level adjustment an audio 
man at a transmitter has little to do un- 
less he is playing a record, making a re- 
cording, or monitoring a studio program. 
His attention may be intense for a few 
seconds or minutes each hour but the re- 
mainder of his time can be utilized for 
other duties. 

The transmitter man has little to do 



448 



October 1953 Journal of the SMPTE Vol.61 



SWITCH BOARD 


















TELEVISION 
TRANSMITTER 








f.OJtCTOt ICMOTt 



*M ANC It CONTROL 



X 




"'" 


.uo,o 


ALL AUQ 


K> fc*r 


o 




I! 



i 




STUDIO 12 19 USED 
FOR LIVE COMMERCIALS. 
NEWS ETC 



MODIFIED 
AUTO SLIDE 
PROJECTOR 



D 




Q MODIFIED 

-_ AUTO SLIDE 
Q PROJECTOR 



Fig. 1. Floor plan of KRON-TV transmitter building on San Bruno Mountain, 
showing the arrangement of its facilities. The audio and video control equipment 
is arranged in a U-shaped console in the transmitter room. The film equipment in 
the adjacent room is remotely controlled and is usually unattended. The auxiliary 
live studio is used for late-at-night programs. The main studios and offices are located 
in downtown San Francisco. 



Isberg: TV Station Film Operation 



449 



other than to check filament voltages, 
read the essential meters, be cognizant 
of the operating condition of the trans- 
mitter and to keep the FCC engineering 
log. The duties of audio switching and 
monitoring as well as the responsibility 
for the transmitter can be assigned to one 
man provided the audio equipment is 
located in the transmitter control room. 

The addition of a video program source 
such as test pattern or microwave to the 
same man's responsibilities is no hardship 
provided the switching equipment for 
video and audio are conveniently ar- 
ranged. 

If film or live-camera programs are to 
originate at the transmitter it will be 
necessary to provide another man be- 
cause the combination audio and trans- 
mitter man will not be able to devote 
enough time to shading and video levels 
unless the video programs are short. 
However, film programs of approxi- 
mately ten minutes in a one-hour period 
may be handled by one combination 
audio-video-transmitter man provided 
the switching sequences are simple, and 
the film-camera control unit is con- 
veniently located adjacent to the audio 
equipment in the transmitter room. 

If the projection equipment is noisy, 
it should be located in an adjoining 
acoustically treated room and should be 
operatable by remote control. If quiet 
equipment is available, it may be located 
in the control room near the console. 
By careful program planning and by pro- 
viding remotely controlled motion-pic- 
ture and automatic slide-projection 
equipment as well as specially designed 
95-min film reels, the manpower require- 
ments for the film room can be reduced 
to only the loading of the projectors be- 
tween shows. This can be easily accom- 
plished by either the audio man or the 
video man during the course of a pro- 
gram. 

Emergencies such as lamp failure in 
the projectors, loss of film loops, tearing 
of splices, etc., are relatively infrequent 
and can be controlled by replacing the 



lamps before they have been used for 
their expected life and by careful inspec- 
tion of the film for torn sprocket holes, 
poor splices, etc. It is desirable to 
assign a person to film-room duty if the 
film operating load is heavy, and if 
opaque projection equipment requires 
frequent changing of slide material. It 
is also desirable for the person assigned 
to film-room duty to be responsible for 
the make-up of the film programs but if 
the film room is not easily accessible to 
public transportation or air express de- 
livery service this work may have to be 
done at a downtown studio. In actual 
operating practice it is usually possible to 
utilize a maintenance man for film-room 
duty during periods of peak activity. 

Description of KRON-TV 

KRON-TV in San Francisco is an ex- 
ample of a station which was planned for 
maximum utilization of manpower with- 
out sacrificing operating standards. 
The floor plan and facilities arrangement 
of the transmitter building are shown by 
Fig. 1. 

Prior to construction, the functions of 
the personnel were carefully analyzed 
and the equipment was laid out in a full- 
scale mock-up for operational analysis. 
After construction of the station, several 
small modifications of the plan have been 
made to suit operating convenience, but 
several years' successful operation has 
shown the plan to be sound, and the per- 
sonnel are contented and have developed 
additional labor-saving innovations. 

All equipment having controls is 
located in the U-shaped operating area 
designed for two-man operation when 
programs originate at the transmitter as 
shown in Fig. 2. During test pattern, 
downtown studio programs or network, 
only one man was initially required and 
he was responsible for the television 
transmitter, the film cameras, micro- 
wave facilities and audio equipment. 
Later additional operating requirements 
and other considerations resulted in the 
scheduling of two men during all broad- 



450 



October 1953 Journal of the SMPTE Vol. 61 




Fig. 2. The KRON-TV control area, seen from the auxiliary studio. 



cast periods. The second man is re- 
sponsible for video control and the load- 
ing of the projection equipment. When 
a live camera in the transmitter studio is 
utilized, a third technician is assigned to 
operate it. The transmitter studio is 
only 12 X 19 ft in area, but it is very 
adequate for live demonstrations using 
simple props and title cards. This 
studio is used principally for live com- 
mercials late at night, on holidays and 
week ends when the two large downtown 
studio facilities may not be available. 
Only one five-man studio crew was 
initially required to cover the entire 
week's live programs from the down- 
town studio. 

Live programs are broadcast nightly 
from the transmitter studio utilizing one 
camera. This camera is usually kept in 
motion to add interest to the live pro- 
gram. It is regularly used in conjunction 
with 3-min film shorts featuring orches- 
tras and talent, interspersed with a live 
master or mistress of ceremonies. 

A staff announcer-producer is assigned 
at the transmitter during evening operat- 
ing periods or when the downtown studio 
is not in operation. He is responsible 
for the program log, station identification 



and coordination of programs. Addi- 
tional talent is customarily used for 
commercial demonstrations. 

The left end of the U-shaped operating 
area includes the rack mounted equip- 
ment minus the power supplies. The 
studio-type synchronizing generator is 
contained in one rack; the video equip- 
ment including two microwave receivers, 
two stabilizing amplifiers, a video jack 
panel and two distribution amplifiers 
comprise an adjoining rack; and the 
audio equipment including the limiting 
amplifier, pre-emphasis network, mag- 
netic tape recorder, audio jack panel, 
audio equalizer, and video bar generator 
is located in a third rack. The trans- 
mitter power console is next, and the 
space below the operating shelf is utilized 
for a studio lighting switch panel so that 
the technicians have control of the pre- 
set lights. Next is the "on the air" pic- 
ture and waveform monitor, and then 
the transmitter audio-video control 
panel. Under the operating shelf of this 
console are located the power switches 
for the video and audio equipment. An 
intercommunication panel for talking to 
the film room, the studio, the office, shop 
and front door is located between the 



Isberg: TV Station Film Operation 



451 




Fig. 3. Close-up of the projector remote control and two-channel audio mixer 
panel, located between the line monitor and film camera No. 2. The two large knobs 
at the top control variacs for the fixed slide-projector lamps; the upper bank of 
switches and tally lights are for controlling the automatic slide projectors; and the 
lower bank of switches and tally lights are for controlling the 16mm motion-picture 
projectors. 

The lower part of the panel has two audio mixers, each with a choice of five inputs 
selected by pushbutton, and a VU meter. Below the audio mixer is a panel provid- 
ing remote Start and Stop buttons for the two turntables and a magnetic tape recorder. 



transmitter audio-video control panel 
and the control consoles for the two film 
cameras. Adjacent to the second film- 
camera control is a special console (Fig. 
3), containing two variacs for the slide 
projectors, controls for the two auto- 
matic and fixed-slide projectors and the 
opaque projector, remote controls for the 
two 16mm film projectors, and a two- 
mixer audio channel providing a choice 
of ten audio inputs. This audio console 



permits one-man operation of video and 
audio switching since it places faders, 
selector switches, and remote controls for 
starting and stopping the turntables and 
magnetic tape recorders within easy 
reach of the operator. Since two men 
are usually available, the one-man 
operation is infrequently used. The 
video switcher and program monitor is 
next in line followed by a field-type 
camera control unit for the studio 



452 



October 1953 Journal of the SMPTE Vol.61 




Fig. 4. One of the KRON-TV film cameras is used in conjunction with a 16mm 
film projector, a remotely controlled turret-type 2X2 slide projector, and a "Pro- 
jectall" opaque or baloptican projector. The opaque projector is utilized to project 
a i : 7j-in. news tape over the bottom side of a test pattern. The bottom of the test 
pattern is masked out with opaque tape and is projected as a transparency through 
the automatic slide projector. The news tape is projected as an opaque against a 
black background and is optically superimposed on the test pattern. The light 
intensities of the projectors can be controlled by variacs so that optimum repro- 
duction will result. 



camera. Relay switching of the audio 
and video simultaneously has also been 
installed in the RCA TS10A switcher. 

Completing the "U" on the righthand 
side is a six-channel audio console con- 
taining the equivalent of a relay rack 
full of audio equipment, all of the plug-in 
variety, and two turntables with special 



cuing systems and modifications for re- 
mote relay control. 

The audio system provides two sepa- 
rate program channels, one for the two- 
channel mixer and the other for the six- 
channel mixer, and the outputs of the 
two channels can be combined to feed 
the transmitter. This flexibility is also 



Isberg: TV Station Film Operation 



453 




Fig. 5. The 95-min 16mm film reels are shown on the RCA modified TP16B pro- 
jectors, with Bill Sadler, left, formerly KRON-TV supervisor, and Donald Anderson, 
KRON-TV engineer. This second camera is used with a 2 X 2 slide projector and 
an automatic slide projector. 



utilized in playing recordings through 
one channel feeding a speaker in the 
studio, so that an artist may sing to the 
accompaniment of a recorded orchestra 
without danger of acoustic feedback 
since his voice is amplified by a separate 
channel. 

The film-room equipment at KRON- 
TV is remotely controlled and is nearly 
automatic in operation. The auto- 
matic slide projectors (Fig. 4) have been 
modified for remote control from the 
operating console, and special cams and 
reversible motors have been installed. 
Thus it is unnecessary for a man to be in 
the film room to change slides and since 
each automatic projector is associated 
with one film camera, the video operator 
can easily preview and shade each slide 
before switching it on the air. The film- 



room equipment is laid out for maximum 
efficiency and continuity of operation. 
Since duplicate equipment is provided, 
protection in case of equipment failure is 
assured. 

The original RCA TP16B 16mm film 
projectors have been modified by ex- 
tending the reel arms and by providing 
specially designed Goldberg 95-min film 
reels as shown in Fig. 5. The new 
Eastman projectors are designed to be 
used with 4000-ft reels. Thus a one- 
hour kinescope recording or film feature 
may be spliced to film station identifica- 
tions, film spot announcements and 
another half-hour show and run con- 
tinuously on one projector. The film 
editing and make-up are done by the 
program department downtown, and the 
film is delivered to the technicians at the 



454 



October 1953 Journal of the SMPTE Vol.61 



Film 
Camera Time Program 


Visual 
Source 


Aural 
Source 


1 9 : 29 : 30 Sponsored Announcement 
6 (20) 
1 Station Identification (10) 


F 

XA-2 


SOF 
BM 


1 Q "^0 50 ^0 Frt'rrn Frnnlcir 


Studio B 
Open 1 Cam 
F 
F 
Close 
1 Cam 


SM ET672 
SOF 
SOF 

SM 


6 2 Approx. 9:43 Film Commercial (60) 
f. 


1 Sponsored Announcement 
(20) 
- 1 Sponsored Station Identifica- 
tion (10) 


F 
F 


SOF 
SOF 


- 1 10: 00-1 : 29 : 30 Files of Snoopy Smith 
6 Approx. 10:16 Live Commercial (60) 


Studio B 
F 
Live 
2 Cam 


SOF 
Boom 


Public Service Announcement 
(20) 
1 Sign Off (10) 


XB37 

XA-2 


BM 
BM 



Fig. 6. Example of Operating Work Schedule. 



Explanation of Fig. 6 

Line at left shows film-splicing order as 
assigned by the video-control supervisor; 
during this time segment all film is on one 
reel with black leader spliced in as indi- 
cated by wavy line (number of seconds of 
black leader indicated by adjacent num- 
ber). Black leader provides time to stop 
and start projector for station identifica- 
tion, commercial or another program. 
The Sponsored Announcement (20-sec 
duration) at 9:29:30 is a film (F) and the 
audio is sound on film (SOF). The Sta- 
tion Identification is from a slide (XA-2) 
with an aural announcement from the 
announce booth microphone (BM). It is 
projected while a 6-sec black leader, 
spliced between the sponsored announce- 
ment and the feature film, is run through 
the film projector and is stopped. The 
opening live commercial is done on one 
camera (1 Cam) with a studio microphone 
(SM) and an electrical transcription ET672 
for a theme. The film feature is started on 



a cue from the Program Director and runs 
until 9:43 when a 6-sec black leader pro- 
vides time to stop and start the projector 
for a one-minute film commercial in film 
camera 2 having sound on film (SOF). 
The close of the program is also live and 
another 6-sec stop down black leader 
provides time to stop and start the projec- 
tor. 

Following the closing live commercial, 
the projector is again started on cue to pre- 
sent a 20-sec sponsored announcement, a 
10-sec sponsored station identification both 
with sound on film (SOF) and the next 
feature film. At approximately 10 : 16 a 6- 
sec black leader provides time for stopping 
and starting the projector for a live one- 
minute commercial requiring 2 cameras 
and a microphone boom. Following the 
commercial, the film feature is resumed on 
cue from the Program Director, and at its 
conclusion, a slide XB37 in camera 2 and a 
sign off slide XA-2 in camera 1 with audio 
from the Booth Microphone is utilized. 



Isberg: TV Station Film Operation 



455 




Fig. 7. After films are checked in by the station, the reels are 
placed in bins to await preview screening. The bins are arranged 
in vertical rows by the day of the week, with shelves marked for 
the hour the film is to be shown. 




Fig. 8. Facilities for editing and splicing 16mm films. Each splicing table is 
equipped with one motor-driven rewind and one hand-cranked rewind. The film 
is spliced in accordance with instructions from the video-control supervisor as noted 
on the left margin of the daily work schedule shown in Fig. 6. Reel sizes are 
selected for the particular operating requirement. 



456 



October 1953 Journal of the SMPTE Vol. 6 1 



transmitter by a messenger service. 
Facilities for the film make-up are in- 
cluded in the transmitter film room, and 
all technicians are familiar with the 
techniques. 

Film Program Coordination 
and Responsibility 

In order to achieve a semiautomatic 
film-room operation, it was necessary to 
devise a simple and complete operating 
work schedule. A simplified version of 
the schedule is shown in Fig. 6. 

This work schedule was designed by 
KRON-TV technical operating and 
program personnel and includes all the 
necessary information regarding any 
equipment or facility requirements for a 
given program. The schedule is pre- 
pared several days in advance of the 
broadcast day by the Traffic Department 
from information supplied by the Sales 
and Program Departments. It is sub- 
mitted to the transmitter video-control 
supervisor who checks the schedule with 
respect to film and slide equipment and 
personnel requirements and for any situa- 
tions which are apt to cause operating 
difficulty. Such situations might be the 
scheduling of the use of a 35mm film- 
strip or opaque projection material at 
times when only two technicians are 
assigned at the transmitter. Such a 
situation may require the scheduling of 
another technician to cover the film 
room since the film-strip and opaque 
projectors are manually operated. Their 
use is infrequent, hence there has been no 
need for adding automatic features to 
them. 

While checking the work schedule, the 
video-control supervisor marks it to 
assign the slides to the remotely con- 
trolled slide projectors and to indicate the 
desired splicing order for the various 
films. It is common practice to have a 
10-sec film station identification spliced 
to a 20-sec commercial spot which is in 
turn spliced to a feature film or kine re- 
cording. With the large reels, over an 
hour and a half of film including spots, 




Fig. 9. When the reels are ready, 
they are placed in these "cans" which 
are then locked and shipped to the 
station's transmitter by a messenger serv- 
ice. Transcriptions, records and mail 
are also inserted in these "cans." 



station identifications, etc., can be spliced 
together. This work is normally done 
by full-time film editors at the downtown 
studios (Figs. 7 and 8). The responsi- 
bility for the receiving, inspection, clean- 
ing, editing, splicing and shipping of the 
film is thus principally that of the pro- 
gram department, and the technicians 
treat the prepared film program material 
as though it were a transcription. The 
degree to which the large reels are used 
and the amount of splicing required de- 
pends upon the availability of technical 
personnel. If an extra man is available 
for film-room duty, he can be assigned 
and the film room can be operated on the 
basis of numerous short reels in succes- 
sion. However, the smooth integration 
of 10-sec and 20-sec commercials into a 
30-sec station break is greatly simplified 
by splicing them to the longer films. 



Isberg: TV Station Film Operation 



457 



In the event that a program change 
requires that a film be moved in the 
schedule, deleted or substituted, such a 
change is easily made since splicing 
equipment is available at the transmitter 
film room. In fact, it is not uncommon 
for numerous spots which are used during 
the Friday program to be removed by the 
technicians and spliced to the Saturday 
or Sunday film. Last-minute rearrange- 
ment of slides, or any other equipment 
requirement, has never created serious 
scheduling problems. 

Television Film and Splicing Practices 

The same spots and station identifica- 
tions are used many times. Since they 
are customarily spliced by cementing 
them to another film, they frequently are 
supplied with opaque leader at both 
ends. These leaders are initially 
trimmed to 6 in. and a number of splices 
can be made before it is necessary to add 
additional black leader for splicing. 
Each splice results in the loss of one 
frame-width of film. Obviously if the 
splicing was not done on the opaque 
leader, the film would soon lose either 
visual or aural content. 

Operating experience has indicated 
that splices should not be spaced closer 
than 3 in., otherwise there is danger of 
splice breakage. Some spots are sup- 
plied with "hen scratches" or writing 
on the black leader. This must be 
masked out. Black cellophane adhesive 
tape has been found to be suitable for 
such masking. 

Blooping Sound Tracks. Sometimes it is 
necessary to "bloop" a sound track to 
overcome an objectionable noise when a 
splice passes through the sound head. 
A triangle of black cellophane tape 
applied over the sound track has been 
found very effective. Commercial bloop 
inks require more time because they 
must dry and they are most effective if 
applied with a spray gun and a mask. 
In practice a good audio man can mini- 
mize "bloops" with his fader after a few 
days' experience. He must, of course, 



know when they will occur in order to 
anticipate them. 

Stop-Down Leader. In many instances 
it is necessary to insert an appropriate 
length of opaque leader in the film make- 
up to provide for the showing of another 
film or slide while the film projector 
continues to run without interruption. 
When it is necessary to stop a projector 
to show another film on another projec- 
tor or to utilize another source of pro- 
gram material, approximately 4 ft of 
opaque leader is spliced in the film make- 
up to allow for stopping and starting the 
projector. Such a leader would be 
"cue" marked in the middle by the 
punched hole method. 

Cue Marks. Adequate cue markers for 
16mm film have not been generally 
available. The customary hole punches 
are large and are objectionable to the 
viewer. A small cue marker which 
punches four frames in the upper right- 
hand corner, outside of the television re- 
ceiver mask area, has been made on a 
custom basis and an aural cue marker 
utilizing prerecorded adhesive magnetic 
tape will soon be available. The aural 
cue marker will create a signal which 
only the station personnel can hear and 
will therefore overcome the objectionable 
features of the visual cue. 

Film Splicing Technique. Good cemented 
film splices are easily made and require 
only simple techniques which must be 
thoroughly understood and appreciated. 
The Griswold R-3 Splicer is very ade- 
quate and is used by many television 
stations. It is essential that the emulsion 
on the film be carefully scraped clean. 
This is easily done by clamping the film 
in the splicer and shearing it, then the 
end of the film is moistened and scraped 
with a well-honed scraper. The scraper 
must be kept sharp and clean or it will 
not do a good job. Care should be used 
not to scrape away the film base or the 
splice will be weak. The splicer should 
be well illuminated to facilitate inspec- 
tion of the splice. 

The film cement should be fresh and 



458 



October 1953 Journal of the SMPTE Vol. 61 



should be kept in small bottles which 
should be tightly capped when not in 
use. Film cement is composed of very 
volatile chemicals which are essential for 
dissolving the film base. Eastman Film 
Cement has been very satisfactory. 
Most stations purchase cement in large 
bottles from which they refill the one- 
ounce bottles used at the editing table. 

After a thin coat of cement is applied, 
the splice is clamped in the splicer for 10 
sec. Then one side of the splicer is 
opened to admit air for another 10 sec of 
drying. The splice is then wiped clean 
of excess cement. 

Film Cleaning. Much of the film sup- 
plied to television stations has been 
handled several times and has accumu- 
lated dirt, lint and hair. Film cleaning 
can be easily accomplished in commer- 
cial film cleaners utilizing a solution that 
cleans the film and also deposits a thin 
layer of wax on it for protection, or small 
quantities of film can easily be cleaned 
with soft powder puffs or velvet pads 
saturated in carbon tetrachloride con- 
taining a small amount of beeswax. It 
is necessary to ventilate film-cleaning 
areas since the fumes of the cleaning 
solvent are toxic. 

Maintenance of Projection Facilities. All 
film-projection equipment should have 
regular maintenance to insure that it is 
clean and well lubricated. Most sta- 
tions find it desirable to have one man 
assigned to maintain projection equip- 
ment as well as have the services of a 
manufacturer's service organization. It 
is essential to have compressed air 
available near the projectors to blow lint 
or hair out of the film gate during opera- 
tion and for use during maintenance. 

Film Department Staff. In addition to 
the technicians who operate the station, 
KRON-TV presently has a film-room 
staff of three splicers, one editor and a 
shipping and receiving clerk who also 
has other duties. The editor times film 
features and edits them to fit into given 
broadcast periods with their respective 
commercials. A messenger service is 



utilized to transport the film to the trans- 
mitter film room, which is on San Bruno 
Mountain approximately ten miles from 
the studio by road. 

Conclusion 

Through coordination in scheduling 
programs and assigning appropriate 
facilities, it is possible to operate a tele- 
vision station with essentially unattended 
film-projection equipment. However, 
consideration must be given to possible 
film-room emergencies which can be 
covered by a man who is normally 
assigned to maintenance. 

The number of technical operating 
personnel of a television station can be 
kept small by combining some of their 
operating functions. Film-projection 
facilities installed at a transmitter plant 
will reduce the number of studio person- 
nel required. However, each station's 
situation should be analyzed with respect 
to other convenience and cost factors 
such as program coordination, distance 
and condition of roads. 

The methods of operation, as de- 
scribed in this paper, were developed by 
the management and staff of KRON-TV 
while the writer was its chief engineer. 
Credit is especially due to H. P. See, 
Manager of KRON-TV, for the in- 
auguration of these policies, and to J. L. 
Berryhill, KRON-TV's chief engineer, 
for his assistance in preparing this paper. 

Discussion 

Harry R. Lubcke (Consulting Engineer}: 
Would you say, on the basis of KRON's 
experience, that, if the studio wer$ supplied 
with one of the remote-controlled cameras, 
the men would have time to manipulate 
that also? 

Mr. Isberg: Oh, yes. These practices 
which I've described for KRON-TV 
mountain operations certainly apply to 
studios. In other words, I have described 
a divided studio and transmitter operation 
having film facilities and a one-camera 
studio at the transmitter. This camera is 
electrically adjusted from the operating 



Isberg: TV Station Film Operation 



459 



console in the transmitter room. Possibly 
I still don't understand your question. 

Mr. Lubcke: No, I don't believe you do. 
There is a certain organization, with which 
I have no connection, which manufactures 
a camera that can be panned and tilted 
remotely by automatic control and I was 
wondering if these men of yours would 
have time enough to use that in a practical 
way? 

Mr. Isberg: Since I've had no experience 
with it, I'm not sure. A cameraman is 
normally assigned to the transmitter 
studio, but if someone, possibly the pro- 
gram man, were operating the remote 



controls of a remotely controlled camera, 
that was dollying itself around the floor 
and panning, and so forth, it might be 
all right. 

Mr. Lubcke: May I put the question 
this way. The technicians have a little 
spare time. Gould they use this equip- 
ment if they had it? 

Mr. Isberg: There isn't very much time 
for additional technical duties as we 
presently operate. But by slight modi- 
fications of program formats and pro- 
cedures they could probably learn to use 
the remotely controlled camera. 



460 



October 1953 Journal of the SMPTE Vol.61 



A Mathematical and Experimental Foundation 
for Stereoscopic Photography 



By ARMIN J. HILL 



The system of stereoscopic photography developed by the Motion Picture 
Research Council, and now generally used in the major Hollywood studios, 
has been based upon extensive experimental data regarding the processes 
involved in binocular vision. It is now known that this vision does not give 
absolute location of points in space, but rather that it is sensitive to small 
differences in distance and direction. Therefore, it appears logical to use 
differential rather than integral forms in calculating probable appearances 
of projected pictures. It is found that this approach removes many of the 
troublesome restrictions found in suggestions based upon other assumptions. 
Perspective and apparent depth can be balanced for pictures seen from the 
better viewing positions in motion-picture theaters. It is also possible to 
include necessary psychological factors to allow satisfactory photography of 
close-ups and other special effects. The result is that if certain simple limita- 
tions and precautions are observed, it is not difficult to obtain stereoscopic 
motion pictures which are consistently natural in appearance and easy to view. 



X HE Motion Picture Research Coun- 
cil has developed a system of recom- 
mendations for the photography of 
stereoscopic motion pictures which in 
many respects is quite different from most 
of those which have previously been 
suggested. Therefore it is desirable to 
review the basic theory of the trans- 
mission and viewing of stereoscopic 



Parts of the subject matter of this paper 
were presented on October 9, 1952, at 
the Society's Convention at Washington, 
B.C., and on April 28, 1953, at the Society's 
Convention at Los Angeles, by Armin J. 
Hill, Motion Picture Research Council, 
1421 North Western Ave., Hollywood 27, 
Calif. 
(This paper was received September 8, 1953.) 



pictorial information in the light of 
what is now known about the processes of 
binocular vision in order to show that the 
Research Council system has been estab- 
lished on a sound theoretical basis and 
that it has been possible to determine the 
necessary constants experimentally in 
such a manner that they can be con- 
sidered reliable. 

These recommendations have now 
been used in critical comparative tests 
in many of the studios and have found 
enough application in actual production 
to show that they are capable of giving 
excellent results. In fact these results 
have adequately demonstrated that the 
approach which has been used is correct, 
and that the mathematical foundation on 



October 1953 Journal of the SMPTE Vol.61 



461 



SYMBOLS 

Note: In general primed symbols refer to quantities in the projected image space (in the 
theater) corresponding to the unprimed quantities in the object space (before the camera). 
The subscript o is used when quantities are referred to the apparent position of the observer 
when this does not coincide with the camera position. 



a Distance from plane of convergence to 

object 

b Interaxial spacing of camera lens 
e Interocular distance of observer 
/ Focal length of camera or lens-film 

distance 

f p Focal length of projector lens 
G "Giantizing" factor in general equation 
m Magnification as given by w'/w 
m "Reduced" magnification as given by 

m(b/e) 
M s Screen magnification as given by 

WJw p 

p Distance from camera to plane of con- 
vergence 

s Integrated angular distance in percep- 
tive space 



u Width of object not in plane of con- 
vergence 

v Distance from observer to theater 
screen 

w Any horizontal distance in the plane of 
convergence 

w p Width of projector aperture 

W 9 Width of projected picture on screen 

Angle of elevation in bipolar coordi- 
nates 

(f> Bipolar latitude 

7 Bipolar parallax or angle of conver- 
gence 

i) Distance factor 

p Distance (or nearness) ratio 

(r, n Luneburg Constants 

T Modified bipolar parallax given by 



which it rests will probably serve as well 
in solving future problems in this type of 
photography as it already has in solving 
some of the more basic ones. 

The Research Council System 

The system of recommendations de- 
veloped by the Research Council is 
characterized by several features which 
are either different, or which are treated 
differently from those in other systems. 
The more important of these are : 

(a) Use of a relatively, but not absolutely, 
fixed interaxial spacing: The interaxial 
spacing is found to be related to the focal 
length of the lenses rather than to depend 
only upon the distance from camera to 
object. Therefore it is varied in a man- 
ner quite different from other stereo- 
graphic systems. 

(b) Allowance of limited divergence in 
lines of sight: Lines of sight to background 
points can be allowed to diverge slightly. 
The amount of this divergence is strictly 
limited in accordance with reliable data 
from numerous optometric tests, and a 
factor of safety is allowed so that no one 
with normal vision will have any diffi- 



culty viewing such points. However 
this slight divergence allows a freedom of 
camera setting and motion not possible 
with most of the other systems. 

(c) Establishment of forescreen reference 
planes: Two reference planes are estab- 
lished for control of forescreen action. 
One of these is the limit for maintaining 
good proportion in the appearance of the 
projected picture. The other limits the 
distance objects can be forescreen and 
still be seen distinctly. 

(d) Special treatment of close-ups: The 
psychological effect of the close-up has 
been taken into account to make pos- 
sible very acceptable close-up photog- 
raphy. 

(e) Special formulation for distant shots: 
The general formula which has been de- 
veloped shows that distant shots require 
a somewhat special treatment. This has 
been applied with very satisfactory 
results. 

(f) Use of "normal" procedures on the set: 
Perhaps one of the most distinctive and 
desirable features of this system is that it 
requires few changes in accepted camera 



462 



October 1953 Journal of the SMPTE Vol. 61 



techniques. The cameramen and assist- 
ants handle all the necessary calculations. 
Distances are measured from the camera 
in feet and inches. Camera motion is 
used in about the same way as it has been 
for "flat" photography. Long, medium 
and close shots are used in about the 
same proportion, and the use of different 
lens focal lengths can be very similar to 
that which has previously been accepted 
as good practice. In short, most of the 
techniques which are already well 
known to experienced cameramen can be 
used with good effect in this new 
medium. 

In addition to these special features, 
this system has several which are com- 
mon to most of the other systems of 
stereoscopic photography. Among these 
may be mentioned : 

(a) The establishment of a "plane of 
convergence" in the set which will cor- 
respond to the plane of the screen in the 
theater. 

(b) The establishment of geometric 
image positions according to generally 
accepted principles of stereoscopic trans- 
mission. 

(c) The use of sheet polarizers in 
projector filters and viewers, use of dual 
cameras and double film in taking the 
pictures and (at present) of double syn- 
chronized projection, with individual 
viewers required for each spectator, all 
of which are common to most of the sys- 
tems being used successfully in the 
presentation of stereoscopic pictures to 
theater audiences. 

How Does This System Differ 
From Others? 

Most of the systems which have been 
proposed for the photography of stereo- 
scopic motion pictures are based on the 
assumption that binocular vision gives 
an absolute estimate of distance and a 
definite indication of the angles taken by 
the lines of sight in viewing an object. 
It is therefore necessary to have the pro- 
jected image points so related to each 
other that lines of sight for a spectator 



in the theater will have the same direc- 
tion as the corresponding lines for the 
taking camera. 

An immediate consequence of this as- 
sumption is that the interaxial spacing 
must be proportional to the distance 
from the camera to the object, and in 
most of the suggested formulae the re- 
quired spacing is so small for practical 
taking distances and reasonable screen 
sizes that the results invariably show 
the distortion referred to as "cardboard- 
ing" wherein the objects appear to be 
flattened into distinct planes at varying 
distances from the camera. 

Another assumption which has been 
made quite generally and which has some 
experimental justification is that under 
no conditions should lines of sight to 
corresponding image points ever be 
allowed to diverge. It can easily be 
shown that this assumption makes im- 
possible the photography of "deep" 
scenes and their subsequent projection 
upon full-sized theater screens unless the 
interaxial spacing is again reduced to 
such an extent that "card boarding" 
is apparent. 

Modern research in the process of 
binocular vision has adequately shown 
that such vision does not, of itself, give 
much information on the absolute dis- 
tance of an object from the eyes. 
Neither is there any mechanism in the 
visual processes which indicates the 
angles of the lines of sight. On the other 
hand, binocular vision gives a very sensi- 
tive indication of relatively small differ- 
ences in distances and of small differences 
in the directions of the lines of sight. It 
is these differences which are used to give 
the binocular depth effects upon which 
successful stereoscopic photography de- 
pends. Therefore any theory which 
is to give successful results must logically 
be based upon these differences offtistance 
and direction rather than upon total or 
absolute values. 

When such a theory is used, it becomes 
apparent that the binding limitations 
of the other assumptions are no longer 



Hill: Stereoscopic Photography 



463 



valid. The interaxial spacing need not 
be proportional to the taking distance, 
and since the eyes cannot detect the ac- 
tual directions of the lines of sight, there is 
no real reason that these lines cannot 
diverge slightly. It is therefore possible 
to photograph pictures in such a manner 
that all dimensions of an object will 
appear in natural proportion, and these 
proportions can be balanced with the 
perspective so that within acceptable 
approximations, at least, the projected 
stereoscopic pictures will appear as the 
natural scene did from the apparent 
camera position. 

The projected picture will no longer 
have the same geometric proportions as 
the natural scene, but will appear to have 
them when viewed from the better posi- 
tions in an average theater. Distortions 
which are caused by viewing the picture 
from an angle, as from a side seat, or 
which vary with the viewing distance, of 
course cannot be eliminated. However, 



it can be shown that over a comparatively 
large viewing area stereoscopic pictures 
can appear to have very acceptable pro- 
portions. This is quite definitely in 
contrast to the concept of the "ortho- 
stereoscopic" position based upon the 
strictly geometric assumptions of other 
systems. 

In order to obtain the proper effects, 
clues which may reveal the absolute dis- 
tance to projected image points must be 
suppressed, and it may not always be 
possible to do this. Then it becomes 
necessary to take the conflicting effects 
into account and work out an acceptable 
compromise. 

Experience has shown that in most 
actual situations the theory which is 
presented here gives effective and satisfy- 
ing results. Necessary modifications can 
be made without guesswork or extensive 
testing. Most important of all, the re- 
sults appear natural and are easy on the 
eyes, giving a very pleasing overall effect. 



I. THE BASIC FORMULAE FOR STEREO-TRANSMISSION 



The Three Spaces 

It is convenient in discussing the prin- 
ciples of stereo-transmission to speak of 
the object space as that in front of the 
camera, the projected image space as that 
containing the geometric image positions 
in the theater, and the perceptive, or ap- 
parent image space as that containing the 
image points as they appear to be re- 
lated to each other in the perception of 
the spectator. In this portion of the dis- 
cussion we shall be interested in the 
relationship between the object space and 
the projected image space. Later we 
will show how the transformation can be 
made into the perceptive image space so 
that we can predict approximately the 
results as they will appear to the ob- 
server. 

The Plane of Convergence 

First, let us determine those reference 



points which are common to both the 
object and projected image spaces. If 
two projectors are properly aligned and 
used to project identical prints on the 
screen simultaneously, these prints should 
exactly overlap at least at the center. 
Accepted practice now uses this same 
alignment for projecting stereoscopic 
pictures. Since these prints are each 
guided from one edge, this means that 
corresponding point pairs which are 
exactly the same distance from these 
edges will exactly coincide on the screen, 
and will therefore appear to be in the 
plane of the screen. 

A little consideration will show that 
such point pairs will represent object 
points which are in an approximately 
plane surface at some distance in front 
of the camera, and perpendicular to the 
direction in which the camera is pointed. 
This assumes of course that the lenses are 
properly matched and that other factors 



464 



October 1953 Journal of the SMPTE Vol. 61 



are such that the two pictures are very 
nearly the same size. 

Let us refer to this (approximate) 
plane in the object space which contains 
those points whose stereoscopic image 
point pairs coincide at the plane of the 
screen in the image space, as the plane 
of convergence. 

Principal and Photographic Axes 

Now let us define the principal stereo- 
scopic axes of the two lens-film systems in 
the stereoscopic camera as those optical 
rays drawn through the lens nodal points 
from the points on each film which will 
be projected at the center of the screen. 
These will not necessarily coincide with 
the optical axes of the systems. How- 
ever if they are extended far enough into 
the object space, they will intersect in the 
plane of convergence. The angle be- 
tween these two axes is known as the 
convergence angle, or sometimes as the 
convergence parallax. 

Of more practical use to the camera- 
man are the photographic axes, which are 
defined as those through the centers of 
the equivalent projector apertures in the 
camera film plane and the nodal points 
of the respective lenses. These axes 
will coincide with the principal axes 
only when the position of the film rela- 
tive to the camera lens, the handling of 
the film through processing, and the 
alignment of the projectors are all such 
that the projector aperture as outlined 
in the camera ground glass coincides 
with the area of the film which is actu- 
ally projected on the screen. 

The Plane of Convergence and 
the Screen Plane 

In order that the photographic and 
principal axes will be coincident, and 
therefore that the intended plane of 
convergence will actually coincide with 
the screen plane, it is customary to align 
the cameras so that their photographic 
axes coincide on some well-defined verti- 
cal object which is in the intended plane 
of convergence. If the stereoscopic 



images of this object then coincide when 
projected on the screen, it is known that 
the axes are properly aligned and that 
alignment has been maintained through 
the film processing and projection. 

With the definitions we have given, it 
is apparent that the plane of conver- 
gence in the set (object space) be- 
comes the plane of the screen in the 
theater (image space). Furthermore, 
unless correction is to be made in proc- 
essing or projection, this plane will be 
that containing the points upon which 
the photographic axes of the camera actu- 
ally converge. Therefore it is conveni- 
ent to use it as the basis for the mathe- 
matical relationships between the object 
and projected image spaces. 

A plan view of the geometry involved 
in this relationship is shown in Fig. 1. 
Here three points are represented along a 
line from the camera perpendicular to 
the plane of convergence. Point A is at 
the plane of convergence in Fig. 1 (a), 
and so its two image points coincide at 
the screen in (b). Point B is nearer the 
camera and its image points are therefore 
doubled so that the one seen by the right 
eye (BR) is to the left of the one seen by 
the left eye (B). The lines of sight 
from the observer at point will there- 
fore intersect at (B'} which is the geo- 
metric image point of the object point B. 
The point C is beyond the plane of con- 
vergence. Therefore, (R) is to the 
right of (C), and the lines of sight inter- 
sect behind the screen plane at the image 
point C 1 . 

Let us use p for the distance from the 
camera to the plane of convergence and 
a (with suitable subscript) for the dis- 
tance from this plane to an object point. 
In the image space, let v represent the 
distance from observer to screen, and a' 
the distance from the screen to the 
image point. (In each case distance 
away from the camera or observer is con- 
sidered positive, that toward them 
negative.) The interaxial spacing of the 
camera lenses (distance between front 
nodal points) is indicated by b. The 



Hill: Stereoscopic Photography 



465 




OBSERVER 



Fig. 1. Lines of sight in taking and viewing stereoscopic pictures. 



interocular of the observer is e. Any 
width (or other dimension in the plane of 
convergence) will be designated by w 
with an appropriate subscript when in 
the object space and by a corresponding 
w' in the image space. Focal length 
of the camera lenses will be designated by 
/, and this will also be used to designate 
lens-film distance, since for all but a few 
special cases this will be effectively the 
focal length. The focal length of the 
projector will be designated by//,. 

Magnification 

The screen magnification, M s , is the ratio 
of a linear dimension in the projected 
picture on the screen to the correspond- 
ing dimension on the film. It can be 
found by dividing the projection dis- 
tance by the lens-film distance in the 
projector, or for practical purposes by 
dividing the projection distance by fp. 



It may also be found by dividing the 
width of the projected picture on the 
screen (without masking), W s , by the 
width of the projector aperture, wp, 
which for standard projection is 0.825 in. 
A more convenient quantity in the 
mathematical development given here is 
the overall magnification of the photo- 
graphic-projection process. This will be 
designated by m and is defined as the 
ratio of a linear dimension of an image 
in the plane of the screen to the corre- 
sponding dimension in the plane of 
convergence. For example, if a man 6 
ft tall is photographed in the plane of 
convergence, and his projected image on 
the screen is 1 8 ft tall, the magnification 
is 3. 

Distance Ratios and Factors 
Nearness Ratios 

Let us now refer to Fig. 2, which is 



466 



October 1953 Journal of the SMPTE Vol. 61 



SCREEN 




RVER 



(a) (b) 

Fig. 2 Geometry of stereoscopic transmission. 



similar to Fig. 1 , except that it shows only 
a single point A which is at a distance a 
behind the plane of convergence. The 
point may just as well be in front of this 
plane, in which case a becomes negative, 
or at the plane of convergence in which 
case a is zero. It is seen that by using 
similar triangles 



. 
and - = -j- - 

v w -\- e 



(1) 



Let us designate the ratio a/p as the ob- 
ject distance ratio, and a'/v as the image 
distance ratio. When a' is negative, the 
absolute value of a'/v can also be re- 
ferred to as the nearness ratio. 

It will be noticed that the image dis- 
tance ratio depends only upon the value 
of w' and e. Therefore it will be the 
same for all observers who have the 
same interocular, and since the interocu- 
lar does not vary a great deal from one 



person to another, we can say in general 
that the image distance ratio is practi- 
cally the same for all observers in the 
theater. 

It is sometimes more convenient to 
use distance factors rather than distance 
ratios. These are given in the form 

(2a) 



b p + a 
for the object space and 



v + a' 



(2b) 



in the image space. 

The Basic Formula for 
Stereo-Transmission 

Now, from the definition of the magni- 
fication we have 

w' = mw (3) 



Hill: Stereoscopic Photography 



467 



Table I. Distance Factors and Ratios in the Image Space. 



Geometric image Distance 
position factor 


Distance 
ratio 


SpottiswoodeV 
nearness factor 


At infinity 1 
At screen plane 
. 5 way from screen to observer 1 

0.8 ' " -4 


Infinity 
1 
-0.5 
-0.8 



1 
2 
5 


so that 


and conversely 




77' = m(b/e)i (4) 


77 = p/(l + p) and 77 


' =P7(1 +P') (7) 


or in still simpler form 


Table I gives the 


distance factors and 



(5) 



where m = m(b/e) is known as the re- 
duced magnification, or in the Research 
Council system simply as the "M value." 
We have here, then, a very simple and 
convenient expression which relates all 
the essential information in the pro- 
jected image and object spaces. In 
other words, it is the basic equation of 
stereo-transmission between these spaces. 
If we use p and p f to represent the 
distance ratios, it is easily seen that these 
are related to the distance factors by the 
equations 

P = 7,7(1 -77) and p' = 7,7(1 -T,') (6) 



ratios for various points in the image 
space and compares them with the "near- 
ness factors" suggested by Spottiswoode. 1 
Note that the nearness ratio which we 
have defined as the absolute value of the 
distance ratio actually specifies the rela- 
tive distance of the image point from 
screen to the distance of the observer 
from screen. Also, it is seen that the 
numerical value of the distance factor is 
one less than Spottiswoode's nearness 
factor. 

One of the most noticeable effects 
when stereoscopic pictures are pro- 
jected on full-sized theater screens as 
contrasted to their projection on the 
comparatively small screens used in 



Table II. Nearness Ratios in Object Space for Different M Values. 



Nearness ratii 
in theater 


9 


Nearness ratios in front of camera for given m 


m *! 


2 


3 


4 


5 


6 


7 


8 


10 


0. 


1 





.10 


0.05 


0.03 


0.03 


0.02 


0.02 


0.02 


0.01 


0.01 


0. 


2 





.20 


0.11 


0.08 


0.06 


0.05 


0.04 


0.03 


0.03 


0.02 


0. 


3 





.30 


0.18 


0.12 


0.10 


0.08 


0.07 


0.06 


0.05 


0.04 


0. 


4 





.40 


0.25 


0.18 


0.14 


0.12 


0.10 


0.09 


0.08 


0.06 


0. 


5 





.50 


0.33 


0.25 


0.20 


0.17 


0.14 


0.12 


0.10 


0.09 


0. 


6 





.60 


0.43 


0.33 


0.27 


0.23 


0.20 


0.18 


0.16 


0.13 


0. 


7 





.70 


0.54 


0.44 


0.37 


0.32 


0.28 


0.25 


0.23 


0.19 


0. 


8 





.80 


0.67 


0.57 


0.50 


0.44 


0.40 


0.36 


0.33 


0.29 


0. 


9 





.90 


0.82 


0.75 


0.69 


0.64 


0.60 


0.56 


0.53 


0.47 


1. 





1 


.00 


1.00 


1.00 


1.00 


1.00 


1.00 


1.00 


1.00 


1.00 



Note: The ratios of 0.5 and 0.8 (in image space), shown in boldface, are those recommended 
as reference "near points" in the Research Council system. These are discussed more 
fully in a later section. 



468 



October 1953 Journal of the SMPTE Vol. 61 



amateur photography is the distortion 
in any subject matter which comes fore- 
screen. The reason for this is at once 
apparent when we consider the relation- 
ship between the nearness ratios in the 
image and object spaces for theater 
screen projection. Using Eq. (5) and 
the relationship of Eq. (7), we find that 



(8) 



from which we can tabulate the nearness 
ratios (absolute values of distance ratios) 
for the object space to give a specified 
ratio in the theater for various reduced 
magnification values. In most cases this 
reduced magnification value will be of 
the order of 3 or more, and for close-ups 
may approach 10. The small distance 
which any object can be toward the 
camera from the plane of convergence 
under these conditions is quite apparent 
from the values given in Table II. 



II. THE TRANSFORMATION TO PERCEPTIVE SPACE 



So far, we have considered only the 
geometric configuration of the image 
points in the projected space and their 
relationships to corresponding points in 
the object space. While these relation- 
ships are very useful in establishing cer- 
tain important limitations which will be 
discussed later, they tell us but little about 
how the picture will appear to an ob- 
server in the theater. In order to ob- 
tain this information, we must consider 
the processes of perception, and if pos- 
sible, transform our geometric forms from 
projected image space into perceptive 
space. In doing so, we will of course 
expect that no mathematical results will 
adequately account for the wide variety 
of differences found between individuals, 
and we must also expect that many im- 
portant factors will be overly simplified 
or perhaps neglected entirely. Such 
an approach, however, has been found 
to give a formulation for setting the 
camera which is quite different from any 
obtained by using only the geometric 
image space, and under actual test con- 
ditions the results have adequately 
demonstrated the soundness of taking the 
perceptive space into consideration as 
adequately as has been possible. 

An apparently reasonable, but none- 
theless mistaken, assumption often made 
in establishing the theory of stereo- 
scopic photography, is that in some man- 
ner binocular vision serves as a "range 
finding" device and thereby gives a 



good estimate of the actual distance to an 
object. Everyday experiences show, 
however, that if we have no information 
other than that given by stereopsis, or if 
the information we have is not in accord 
with previous experience, we can be 
badly fooled in our estimates of dis- 
tance. Carefully conducted tests have 
adequately confirmed such experiences 
and have shown that we cannot make an 
accurate estimate of distance on the basis 
of stereopsis alone. 

Charnwood 2 points out that no mech- 
anism has been found in the extraocular 
muscles which would give information on 
the actual positions of the eyes essential 
for "range finding." He further shows 
that such "proprioception" would actu- 
ally be a hindrance to binocular vision. 
Ogle 3 states that while "the phenomenon 
of stereopsis provides the most vivid and 
accurate relative depth discrimination, 
absolute localization probably results 
from a more complex psychic integra- 
tion of empirical and stereoscopic 
stimuli." Luneburg 4 shows that as a 
result of experiments with an isolated 
point "binocular observation of a single 
point does not differ from monocular 
observation. Both are equally uncer- 
tain as to correlating a sensed point P 
to the physical coordinates of the stimu- 
lating point />*." Charnwood 2 con- 
cludes after analyzing extensive data from 
many recent studies on the subject that 
"stereopsis has no scale and is capable 



Hill: Stereoscopic Photography 



469 




Fig. 3. Modified bipolar coordinates. 

of many interpretations, the choice of 
interpretation being made in response 
to some outside factor." 

Therefore there seems to be general 
agreement on two points: (1) stereopsis 
gives a very accurate relative depth dis- 
crimination, i.e., it will tell the ob- 
server which of two object points that are 
not too widely separated in space is the 
nearer; and (2) binocular vision can- 
not, of itself, give a reliable estimate of 
actual or absolute distance from an ob- 
server to an isolated object point. In- 
cidentally, these are in agreement with 
other sensory perceptions, for in general 
it is found that while we can perceive 
differences in sensation, we have no direct 
sensation of absolute values. 5 

Mathematical Formulation Modified 
Bipolar Coordinates 

Mathematically, these experimental 
results indicate that we should use differ- 
ential relationships in treating these 
problems of perception. Upon inte- 
gration, we then have arbitrary con- 
stants corresponding to the indetermi- 
nate absolute values which seem to be in- 



herent in the visual processes. These 
constants can then be evaluated upon the 
basis of experience or other empirical 
knowledge, just as we now evaluate them 
in constructing a perception from our 
sensory information. 

It must be kept in mind, in treating 
problems of vision, that the eyes "see" 
only the angles between two object or 
image points, and all estimates of dis- 
tances must be made in terms of these 
angles. Therefore a suitable coordinate 
system for relating points in the pro- 
jected image space and the eyes of the 
observer should use angular values. 
The "modified bipolar coordinates" 
suggested by Luneburg 6 are well suited 
to this purpose and will be used here. 
Figure 3 shows these coordinates in 
terms of the "Vieth-Muller circle" 
through the observer's eyes. The angle 
of elevation (6) gives the angle of the ob- 
ject point above a horizontal plane 
through the eyes. The bipolar latitude (</>) 
gives the angular displacement in the 
horizontal direction, or in other words 
the angular width. The bipolar parallax 
(7) gives the displacement toward or 
away from the observer, and therefore 
indicates what we refer to as "depth." 
All three coordinates will have zero 
values for a point infinitely far away, on 
the horizontal plane through the eyes, 
and in the meridional plane. 

The Basic Assumption 

It seems reasonable to assume that the 
natural results in stereoscopic photog- 
raphy will be achieved when the di- 
mensions, i.e. height, width and depth, 
of an object will appear to have the same 
proportion in the perception of the ob- 
server when he views the projected pic- 
ture, as they would have had he viewed 
the object directly from the position 
where apparently the picture was taken. 
Unless the camera or projection lenses 
have bad distortion, the height and 
width will be maintained in proper pro- 
portion, so that the above assumption 
can be expressed in differential form in 



470 



October 1953 Journal of the SMPTE Vol. 61 



modified bipolar coordinates by the 
equation 

d .-L = +L 
~d<t>' d<t> 



OBJECT POSITION 



(9) 



where the primed values represent those 
for the observer in the theater and the 
unprimed values those for the same ob- 
server if at some position (0) from which 
the picture was apparently photo- 
graphed. A more convenient form is 
obtained by rearrangement, giving: 



d<j> 



(10) 



Of course, if this equation holds, it 
means that only a small region in the 
projected image space will appear to 
have depth in proper proportion to 
width (or height). However it will be 
shown later that this equation can be in- 
tegrated, following suitable geodesies in 
perceptive space, and the results of such 
integration indicate that proper propor- 
tions will be retained within practical 
tolerances throughout the entire picture 
area when the conditions expressed by 
Eqs. (9) or (10) hold. 

Actually, except for a single viewing 
distance, the position from which the 
picture will appear to have been taken 
will not coincide with the actual camera 
position. For a given focal length of 
lens, therefore, there will be a single 
"normal" viewing distance, but at this 
distance perspective and stereoscopic depth 
will be properly balanced. With other 
focal lengths, or at other viewing posi- 
tions, the observer will appear to occupy 
a position (0) shown in plan view in Fig. 
4. Here let u represent a horizontal 
dimension near the object point A (which 
is not in the plane of convergence). 
The angle it subtends at the camera is <, 
and at the apparent position of the ob- 
server is 4> . The distances inter- 
cepted in the plane of convergence are 
w, and w , respectively. When pro- 
jected, the distance w becomes w', and u 
will appear as u ' . The angle subtended 
at the position of the observer in the 




APPARENT POSITION 
OF OBSERVER 



CAMERA POSITION 



Fig. 4. Geometry for photography of an 
extended object. 

theater by w ' will be </>'. From Eq. (3) 
we have 

w ' = mw ( 3 ) 

and from similar triangles we see that 



_ P 



u 
so that 



and 



and - = 
po + a u p + a 



Wo Po P + 



(12) 



(13) 



then, since d<$> 
dw'/v, we have 



i" 

Po P -T a 
= dw /p and d<$>' = 



P Po + * 

m ; 

o p + a 



(14) 



To obtain the relationships for the bi- 
polar parallax angles, it is best to use 
the sketch given in Fig. 5. From this it 
can be seen that (since all angles are 
very small) : 



Hill: Stereoscopic Photography 



471 



PROJECTED 
IMAGE POINT 




ERVER 



(a) (b) 

Fig. 5. Bipolar parallax in photography and viewing. 



and 



Therefore 



dy' = - 



eda 



(pc 



or 



</ To ( + a') 2 
Now from Eq. (5) we have 



b a 

m - 



v + a' 
(15) 



(16a) 



(16b) 



giving 



which, when substituted in equation 
(17) gives 

t' = m - ^ Po + "' 



(P + ) 2 

Equating this to the right member of 
Eq. (14), we find that the condition for 
which Eq. (10) is valid is that 

P (Po + a) _ P b (p + , 



v (p 
(18) or that 



v -\- a' e p -\- a 

from which we obtain by differentiation e (p 

472 October 1953 Journal of the SMPTE Vol.61 



(23) 



2.80 



'/S< WITH INTERAXIAL SPACING 
PROPORTIONAL TO TAKING DISTANCE 



S,'/S, (DEPTH) WITH INTERAXIAL- INTEROCULAR 



S-'/S, (WIDTH) 




60 80 100 120 140 

DISTANCE FROM CAMERA TO OBJECT- FEET 



180 200 



Fig. 6. Ratios of integrated apparent dimensions in projected image to correspond- 
ing apparent dimensions in object. These curves were calculated using equations 
(26) and (27) under the following assumed conditions: Viewing distance in theater 
is 40 ft. Screen width is 24 ft. Object has a depth of 3 ft and near edge is in plane of 
convergence at all camera distances. Focal length of camera lenses is 2 in. Interaxial 
spacing for solid curve is 2.5 in. 



This is the fundamental equation for 
determining the interaxial spacing so 
that all dimensions will appear in natural 
proportion and that perspective and 
stereoscopic depth will be properly 
balanced. When conditions are such 
that the observer feels he is actually at 
the camera position in other words, 
that p = p this equation simplifies to 

b = e (24) 

The correct interaxial spacing under 
these conditions is therefore the inter- 
ocular distance or about 2.5 in. 

Integration to Include Regions 
of Finite Size 

The above derivation of course treats 
only with infinitesimally small regions 
in the picture. There is no assurance 
that the same conditions will hold over 



finite regions unless we can obtain an 
integral form of Eq. (10). 

Fortunately, the geometry of per- 
ceptual space under conditions similar 
to those used in viewing motion pictures 
has been formulated by Luneburg, 6 
and his equations provide a simple 
means by which this integration can be 
performed. He proposes as a suitable 
metric for this space 

ds* = cschV( 7 + 



cos 2 <f>d6 z ) (25) 

where the angles are those which have 
already been defined and a and /* are 
constants which vary somewhat from 
individual to individual. 

For simplicity we can use r = a(y + 

fr 

Apparent distance along any coordi- 
nate line, i.e. with only one variable 



Hill: Stereoscopic Photography 



473 



WIO OF APPARENT DIMENSION OF IMAGE TO THAT OF OBJECT 
D00--r\>r\jiv 

3 8 8 S 8 S g 


it 














3 
























'. 














/ 


S,'/S, WITH INTERAXIAL 
PROPORTIONAL TO 


SPACIN 
TAKING ( 










a 












/- 


- 


G "^ 
)ISTANCE 






V 


\ 




















\ 








7 

/ 
































V V 
\ 


\ 




/ 




/ S//S y (DEPTH) WITH 


INTERAXIAL 


'INTEROCULAR 








^ 


^- 

7 
i 


/ - 

^T 


-1 


/ 
^ (WIDTH) 


J 


1 


=!=^ 










^ ^ 


MK= 





- 






























/ 
































/ 






































i 








































/ 






































/ 

















































































200 



DISTANCE FROM CAMERA TO OBJECT- FEET 



Fig. 7. Ratios of integrated apparent dimensions in projected image to correspond- 
ing apparent dimensions in object. These are calculated under the same assumed 
conditions as those in Fig. 6, except that the object is assumed to have a depth of 20 ft. 



changing at a time, can be obtained by 
integrating Eq. (25), assuming the dif- 
ferentials of the unchanging coordinates 
as zero. Thus a change in apparent 
depth, s y , would be given by 

Sy = J*J^ csch rdr = log e tanh (r 2 /2) 
log e tanh (n/2) (26) 

Likewise an apparent width (angular) 
is given by 



= csch 



(27) 



and apparent height (again angular) by 

se = csch T cos <f> Jlf z de 

= (dz 0i) csch T cos (28) 

These distances are all given as angles, 
but as has been pointed out before, 
it is these very angles which the eyes use, 
and only through them can any estimate 
of actual distance be made. The condi- 
tion, therefore, that apparent dimen- 



sions shall be in the same proportion as if 
the observer had been at the camera 
position will be given by the equations 

sy'/sy = s^'/st = SB' 1 59 (29) 

where the primed values represent those 
seen in the theater and the unprimed 
ones those which would have been ob- 
served at the camera position. 

Actually, due to the forms of Eqs. 
(26) to (28), these cannot be exactly 
consistent. For example, Eq. (28) has a 
cos <f> factor which does not appear in 
Eq. (27). This indicates that there will 
be a slight barrel distortion toward the 
edges of the field of view, and this may 
not be the same in the theater and before 
the camera when the other factors are 
selected for best balance. The error will 
be proportional to the differences in co- 
sines of the angular field of view, however 
and within the range ordinarily used in 



474 



October 1953 Journal of the SMPTE Vol. 61 



2.80 

i 

JI2.40 
2.00 

Hi. 60 
o 

fi-> 
ZQ80 

040 
g 
<$ non 
























































































































































































































S^ (WIDTH) 






_ 


i^ 












- - 




r 






x' 

"X 


*~ 


/-J 

^= 


-^ 


S,VS, (DEPT 


i 



















H) 






















f 


'/ 






































// 






































'/ 































































































































































20 



40 



60 80 100 120 140 

DISTANCE FROM CAMERA -FEET 



160 



180 200 



Fig. 8. Ratios of integrated apparent dimensions in projected image to correspond- 
ing apparent dimensions in object where the observer is apparently between the 
camera and the object. In these curves, the object depth is assumed to extend from 
the plane of convergence back to indicated distance from camera, and therefore varies 
with distance whereas in Figs. 6 and 7 it was assumed to be constant. Here the plane 
of convergence is assumed to be kept constant at 30 ft from the camera. Screen width 
is 24 ft, and viewing distance is 700 in. or 58.3 ft. Focal length of camera lenses is 3 
in. and interaxial spacing is fixed at 3.5 in. This gives a picture which appears as 
if viewed from a point 20 ft in front of the plane of convergence. 



motion-picture projection, this will prob- 
ably never be serious. 

If we assume therefore that the hori- 
zontal and vertical components s^ 
and so, respectively, are proportional to 
each other, the condition that the depth 
will also be in proportion is that 

sv'/s y = VA* (30) 

It is easiest to check this relationship 
by plotting these ratios for specific 
conditions, as has been done in Figs. 6 
and 7. These plots show clearly that 
under the assumption that interaxial 
spacing is the same as the interocular 
distance, dimensional proportions will 
hold quite closely for all camera dis- 
tances except those used for the largest 



close-ups. Of course these assume that 
lens focal lengths and viewing conditions 
are such that the observer feels that he is 
at the camera position. A more general 
case is shown in Fig. 8, where the ap- 
parent position of the observer is be- 
tween the camera and the plane of 
convergence. 

In order to compare the results of the 
above relationships with those based 
upon the assumption that the interaxial 
distance should vary with distance from 
camera to object, similar dimensional 
ratios for the latter assumption have 
been plotted in dashed lines in each 
of Figs. 6 and 7. The error in this as- 
sumption is immediately evident, for 
at only one distance (orthostereoscopic 



Hill: Stereoscopic Photography 



475 



MOTION PICTURE 

RESEARCH COUNCIL 

3-D CALCULATOR 




Fig. 9. The Motion Picture Research Council 3-D Calculator. This instru- 
ment, which is of white vinylite 4 in. in diameter, was designed in accord- 
ance with the principles set forth in this paper. It is now in use in the major 
motion-picture studios in Hollywood for the calculation of camera settings 
for their stereoscopic photography. 



condition) are the dimensions in proper 
proportion. 

The General Equation 

A very important psychological factor 
has been disregarded in our discussion 
so far. We have long been accustomed 
to the use of the "close-up" in making 
figures on the screen appear to be very 
near. Most of the projected images are, 
of course, magnified, but these close-up 
views are actually "giantized." They 
have become so basic a part of the mo- 
tion-picture convention, however, that 
we readily accept this giantization as 
normal. 



When close-ups ar^ to be photo- 
graphed stereoscopically, this effect must 
be taken into account, and a correction 
made for this "giantizing." Since we 
unconsciously feel that we are looking at 
a figure much larger than normal, the 
correct interaxial spacing will be less 
than that normally used for medium 
shots. To allow for this, a "giantizing" 
factor G can be inserted in Eq. (23), 
giving the general equation 

(31) 
Good judgment and experience must be 



476 



October 1953 Journal of the SMPTE Vol.61 



used in assuming the values for G, 
p /p, and a in this equation, and the 
selection will depend upon the kind of 
shot which is to be made. The ratio 
pjp will also, of course, depend upon 
the viewing distance and other conditions 
in the theater. Fortunately it has been 
found possible to make acceptable 
working assumptions for each of these 
values, so that satisfactory results can be 
obtained consistently. These have been 
used by the Research Council in the 
construction of a calculator illustrated 
in Fig. 9, which gives the best recom- 
mended settings for various lens focal 
lengths, camera distances and other con- 
ditions. 

Practical Forms of General Equation 

The selection of a suitable value for a 
depends on the "field of interest" in 
front of the camera. This is usually a 
more restricted area than the field of 
view, and its depth can often be given as 
a proportional part of the camera dis- 
tance. For example, let us assume that 
the field of interest is centered beyond 
the plane of convergence at a distance 
from it of about half the camera distance. 
We can assume that a 2-in. focal length 
gives the best perspective relationship 
for the better viewing positions in an 
average theater. This means that 
pjp = 2/f where / is in inches. Using 
a = l /2p and G = 1, we find that Eq. 
(31) becomes 



= e^L 



(32) 



which is an excellent working equation 
for medium shots. 

For telephoto shots, the depth a 
may be very small compared with the 
distances p and p . With these shots we 
want no giantizing effect so that G = 1 . 
Therefore Eq. (31) becomes approxi- 
mately 

b = e (f/2) (33) 

On the other hand, where the field of 
interest extends from the plane of con- 



vergence back to very distant back- 
grounds, the value of a will be very 
large compared with p or p . The factor 
(p + a)/(p -f a) then becomes very 
nearly one, and (since again G is unity), 
the interaxial spacing is given by 

b = e (34) 

regardless of the focal length of the lens. 
For close-ups, it is more satisfactory 
to specify the depth of the field of interest 
in terms of the height of the projected 
picture. This is the usual way of specify- 
ing the close-up; that is, it is a half- 
figure, bust or head, referring to the 
portion of the figure that fills the screen. 
The factor G is then also a function of the 
magnification and a simple expression 
for the interaxial spacing can be ob- 
tained. For example, assume that the 
depth of field of interest a is 5/6 of the 
picture height, h. Then for standard 
apertures 0.600 in. in height,/? = (A/0.6)/, 
and since p = (2//)/>, we find that 
p = A/0.3. Substituting these values in 
Eq. (31) gives 

b = f -^ (35) 



as a very usable equation for close-up 
photography provided suitable values 
of the factor G are known. Incidentally, 
this equation approximates the values of 
Eq. (32) for medium shots closely enough 
for use with lenses having focal lengths 
of 3 in. or less. Results with it have 
verified its usefulness under the specified 
conditions. 

The "giantizing" factor G in Eq. (35) 
is found to be a function of magnification 
only, and was evaluated on the basis of a 
series of actual tests. A plot of the re- 
sults is given in Fig. 10. 

Incidentally the factor G can be used 
for calculating shots which must de- 
liberately be made to appear giantized 
or miniaturized. For example, if a 
scaled-down model with a scale factor 
of 8 is to be photographed to appear 
full sized, the factor G in Eq. (31) should 
be 8. On the other hand, if a model 



Hill: Stereoscopic Photography 



477 



3.0 



o:2.0 
o 



I 10 12 

MAGNIFICATION 



16 



18 



20 



Fig. 10. Relationship between the giantizing factor "G" and magnification. The 
factor "G" is that required in equation (35), and the magnification is that defined by 
equation (3). 



is to appear 1/3 actual size in the pro- 
jected picture, G should be 1/3. Actu- 
ally the problem is not quite as simple 
as this, for additional psychological 
factors, and "showman's license" must 



be taken into account. However, this 
formulation will provide a starting point 
from which tests can be made to deter- 
mine the most satisfactory settings. 



III. DETERMINATION OF FAR POINTS AND BACKGROUND DIVERGENCE 



As mentioned previously, another 
natural assumption which has been 
made by many authorities in the field of 
stereoscopic projection is that the lines 
of sight must not diverge for any homol- 
ogous point pairs. It is felt that such 
divergence would make them appear 
at a distance "beyond infinity," which 
of course could not happen. Funda- 
mentally, this assumption is closely re- 
lated to, and in fact is based on, the 
assumption that the eyes can in some way 
detect the absolute directions of these 
lines of sight. The Luneburg trans- 
formation (Eq. (25)), incidentally, 
handles such divergences, as long as they 



are quite small, without difficulty, indi- 
cating that perhaps fusion can take 
place and objects can be seen in correct 
proportion, even though the lines of sight 
do diverge slightly. Experience shows 
that this indication is correct. The 
eyes actually cannot detect slight di- 
vergences in the lines of sight, and while 
these are admittedly not encountered in 
natural seeing, nevertheless satisfactory 
fusion of images can take place if the 
amount of divergence is kept within 
reasonable limits. 

Restrictions If No Divergence Is Allowed 

Let us first consider the limitations 



478 



October 1953 Journal of the SMPTE Vol. 61 



imposed upon the photography of 
stereoscopic pictures by the restriction 
that no divergence of the lines of sight 
to any homologous point pairs can take 
place in the viewing of projected pic- 
tures. This is equivalent to saying that 
no w' of the kind shown in Fig. 2 can 
exceed 2.5 in. or the normal interocular 
distance. From Eq. (3) then, this 
limits the corresponding value of w for 
objects infinitely far from the camera to 
not more than 2.5/m. At an infinite dis- 
tance, the lines of sight to the camera 
lenses will be parallel and therefore 
the maximum spacing of the lenses will be 



e/m 



Wsep 
wpf 



(36) 



which (except for the different notation) 
is the well known "Wed/sf formula 
given by Rule, 7 Norling 8 and others. 

Projection on theater screens requires 
the use of values of m of the order of 3 
or more for most useful shots. This 
means that for screens 24 ft wide, inter- 
axial spacings must be of the order of 
3/4 in. or less. Such small spacings 
cannot be obtained with 35mm cameras 
without the use of beam-splitting devices, 
with their resultant loss of light. 
Furthermore, they give rise to "card- 
boarding" effects which are always un- 
desirable. 

How Much Divergence Can Be Toler- 
ated? 

Fortunately, it appears possible to 
allow some divergence of the lines of 
sight. Fry and Kent 9 have shown that 
stereo-acuity is fully as sharp with slight 
divergence as with an equivalent amount 
of convergence. In fact, clear single 
vision seems to be possible for most ob- 
servers up to total divergence angles of 
greater than 5 (i.e., 2.5 for each eye). 
There is some evidence that eyes at rest 
apparently turn out approximately 1/2 
each, indicating that there should be no 
physical discomfort even should the 
eyes turn outward to follow the diverging 
lines of sight. Finally, actual tests with 



pictures which have been projected so 
that a divergence in the lines of sight is 
required show that such pictures can be 
fused easily by most observers. They 
look perfectly natural, and no unusual 
strain is set up provided always that cer- 
tain definitely specified limits are not 
exceeded. 

On the basis of these considerations, 
the assumption has been made that a 
divergence of the lines of sight of 1/2 for 
each eye, or a total of 1 negative bi- 
polar parallax could be allowed for an 
observer 40 ft in front of a screen 24 ft 
wide. Such a screen with standard 
aspect ratio, would be approximately 
18 ft high. Since it can safely be as- 
sumed that no screen will ever be ob- 
served at a distance less than its height, a 
minimum viewing distance can be taken 
as 18 (or 20) ft. This will give a diver- 
gence of slightly over 1 for each eye 
which is still less than half of what can 
be safely tolerated by most observers. 

The Maximum Separation Used in the 
Research Council System 

On the basis of the above assumption, 
photography for a screen 24 ft wide 
should be such that no homologous 
point pairs are separated at the screen 
more than 480 X tan 1/2, or 4.19 in. 
for each eye plus the interocular distance 
of 2.50 in. or a total of 10.88 in. The 
Research Council system therefore 
recommends a maximum separation of 
1 1 in. for such point pairs. 

This value will allow the photography 
of infinitely distant points with a "re- 
duced" magnification value of 4.4, in- 
stead of 1.0 as allowed under the condi- 
tion of no divergence. This in turn in- 
creases the maximum allowable value of 
b to 4.4 times the value given by Eq. (36). 
The manner in which this allows much 
more practical camera settings is shown 
in Table III. 

Table III clearly shows the desir- 
ability, and in fact the necessity, of 
allowing a small amount of divergence. 
With the amount specified, it is seen 



Hill: Stereoscopic Photography 



479 



Table III. Comparisons of Camera Settings When No Divergence Is Used 
and When Slight Divergence Is Allowed. 

Setting specified by 

Research 

Condition Eq. (36) Council 

/ = 2 in. Distance to object (plane of convergence) is 10 ft. 

Interaxial . 43 in. 1 . 9 in. 

/ = 3 in. Waist figure close-up. Interaxial . 29 in. 2 . 1 in. 

f = 2 in. Distance to plane of convergence is 10 ft. Distance 

from plane to farthest point in set (interaxial 

2.5 in.) should not exceed 2 ft-1 in. 31 ft 

Same but with interaxial spacing recommended in first line. ... 6 ft-8 in. Infinite 
/ = 2 in. Distance from camera to plane of convergence if 

infinitely distant points are also in scene, using 2.5 

in. interaxial. . 58 ft-4 in. 13ft-3in. 



Table IV. Maximum Separation (in inches) of Homologous Point Pairs on Screens 
of Different Widths for Different Aspect Ratios. 



Width 


Screen 


of 
screen, 


magnifi- 
cation, * 


Aspect ratios (width/height) 


ft 


M s 


4/3 


5/3 


7/4 


1.85/1 


2/1 


7/3 


8/3 






(standard) 














15 


218 


7.9 


6.8 


6.6 


6.4 


6.1 


5.6 


5.2 


18 


262 


9.0 


7.7 


7.4 


7.2 


6.8 


6.2 


5.7 


21 


306 


10.0 


8.5 


8.2 


7.9 


7.5 


6.8 


6.2 


24 


350 


11.0 


9.4 


9.0 


8.7 


8.2 


7.4 


6.8 


27 


393 


12.2 


10.3 


9.9 


9.5 


9.0 


8.0 


7.3 


30 


437 


13.2 


11.1 


10.7 


10.2 


9.7 


8.7 


7.9 


35 


509 


15.1 


12.5 


12.1 


11.6 


10.9 


9.7 


8.8 


40 


582 


16.8 


14.0 


13.4 


12.8 


12.1 


10.7 


9.7 


45 


655 


18.6 


15.4 


14.8 


14.1 


13.2 


11.7 


10.6 


50 


727 


20.5 


16.8 


16.2 


15.4 


14.5 


12.7 


11.5 



This assumes that aperture has standard width 



that relationships between camera and 
set can be kept about as they now are 
for "flat" photography. 

Photography For Wide Screens 

When photography is for wider screens, 
care must be used that the divergence 
which has been specified is not exceeded. 



Assuming that no screens will be viewed 
from less than their height, and that at 
this minimum viewing distance the di- 
vergence of the lines of sight should not 
exceed 1 for each eye, Table IV gives 
the maximum separation of homolo- 
gous point pairs for various screen widths 
and aspect ratios. 



480 



October 1953 Journal of the SMPTE Vol. 61 



IV. DETERMINATION OF NEAR POINTS 



At least three important factors must 
be given consideration when subject 
matter is made to appear between the 
screen and the observer. One of these, 
of course, is the "window" which forms 
the transition between the projected 
picture and the theater. Successful 
composition must take into account its 
effect in each of the three dimensions 
just as the effect of the masking or frame 
must be taken into consideration in 
"flat" pictures. A second factor can be 
termed "psychological" distortion, for 
it is caused by the recognition of rela- 
tionships between the projected images 
and reference points in the theater 
and could be largely eliminated by 
projection in a perfectly dark, empty 
room. The third factor is the un- 
natural relationship which must exist 
between the convergence of the eyes and 
their "accommodation" or focus as they 
look at an image point which may be 
relatively near, yet must keep focused on 
the screen plane. 

The Window 

The stereoscopic window is provided 
by the limiting aperture of the stereo- 
transmission system. Since this is usu- 
ally the masking at the screen, and this 
masking will provide the same aperture 
for both pictures, the window is usually 
at the screen plane. This is not neces- 
sary, however, for several more or less 
successful arrangements have been tried 
which project a "window in space" 
whose position is some distance in front 
of the screen. Such a positioning has 
several advantages as will be seen from 
the ensuing discussion. 

With proper alignment of photo- 
graphic and principal axes, the equiva- 
lent positions of the "window" in the 
object space will coincide at the plane of 
convergence when the window is formed 
by the projector apertures (or screen 
masking). This is shown in Fig. 11, 
which shows also the field of view of each 



of the two camera lenses, and of each eye 
of an observer standing in the position 
from which the picture apparently is 
taken (according to the perspective 
given by the lens focal length and viewing 
conditions). 

It is at once apparent that the fields 
of view of the camera lenses and of the 
observer's eyes do not match. There- 
fore there will be a slightly unnatural 
effect near the edges of the picture. 
Vertical objects which appear in one of 
the two pictures but not in the other will 
be particularly confusing. The effect 
of such objects is even worse if they are 
supposed to be forescreen, as then by all 
conditions of natural vision they should 
be visible to both eyes. 

The window, of course, will cut off 
any scenic elements which extend be- 
yond it, even though such elements 
appear forewindow. In other words, 
if any scenic elements such as tree limbs, 
table tops or the like, extend out of the 
window, caution must be used that they 
are not cut off and left "dangling" 
in space over the heads of the audience. 

Psychological Distortion 

The photographic system discussed 
here is based upon the assumption that 
dimensional proportions will appear 
the same to an observer in the theater 
as if he had actually been in the position 
from which the picture appears to have 
been taken. In most cases therefore, 
he must be made to feel that he is actu- 
ally nearer the scene than his distance 
from the screen. Unless he can do so, 
there will be a definite loss of "intimacy" 
and much of the dramatic effect other- 
wise possible from the presentation will 
be lost. 

In order to make the observer feel 
that he is close to the scene, the geo- 
metric depth has been deliberately in- 
creased so that at screen distance the 
projected pictures will present the 
same "see-around" as the real objects 



Hill: Stereoscopic Photography 



481 




APPARENT POSITION 
OF OBSERVER 



CAMERA POSITION 



Fig. 11. Fields of view of camera and observer when 

window is at screen plane. As in all of these illustrations, 

angles must necessarily be greatly exaggerated. 



would at much shorter viewing distances. 
The results are satisfactory, provided no 
clue is given as to the actual distances to 
the projected image points. When these 
points are behind the screen there is 
little likelihood that any external refer- 
ence points can spoil the effect. How- 
ever, as soon as they are brought fore- 
screen, any objects which are visible in 
the theater may serve as reference 
points to give the observer a clue as to 
the actual distances to the projected 
images. For example, if the plane of 
convergence in a side view of an actor 
coincides with the side of his face, so 
that his shoulder and arm are fore- 
screen, these may quite easily come out 
as far as halfway to the observer. Now 
if they do not come near the side of the 



screen or any other visible object in the 
theater, the effect will be quite accept- 
able. However, if it is noticed that, 
say, the front edge of the orchestra pit, 
or the lady with a big hat in the fifth 
row, are well beyond the closer portions 
of the image, the entire effect is lost and a 
definite "stretch" appears. 

This effect is particularly noticeable 
in objects which are intended to come 
entirely forescreen. If they appear to 
do so, they will retain their natural 
proportions, but if for some reason they 
remain tied back to the screen plane, 
the distortion will be quite apparent. 
The reason we speak of this as "psycho- 
logical" is therefore obvious, for it de- 
pends entirely upon the way the image 
positioning is interpreted by the observer. 



482 



October 1953 Journal of the SMPTE Vol.61 



The Accommodation-Convergence 
Relationship 

The effects which have just been dis- 
cussed will at worst cause the projected 
pictures to be unnatural in appearance 
and unpleasant to look at. The un- 
natural accommodation-convergence re- 
lationship required in the viewing of far 
forescreen image points, on the other 
hand, can cause real discomfort, and in 
extreme cases may result in pictures 
which the eyes will refuse to fuse in 
other words, which will be seen as 
doubled. 

In natural viewing, the accommoda- 
tion is subconsciously adjusted to agree 
with the distance at which the eyes con- 
verge, at least for objects in the near 
and medium viewing distances. As 
far away as the screen for average view- 
ing distances in the theater, however, 
changes in accommodation are very 
small even with large changes in con- 
vergence distance, so that little concern 
need be given this factor when images are 
at or behind the screen plane. On the 
other hand, when the image points are 
well forescreen, the eyes are required 
to converge on a relatively near point, 
yet maintain their focus on the distant 
screen. This means that the reflexive 
relationship between accommodation 
and convergence must be broken. 
Some observers can do this quite easily, 
others find it much harder, but generally 
speaking everyone must learn to look at 
forescreen objects in a manner quite dif- 
ferent from that used in natural viewing. 

It is not difficult for most observers to 
readjust this relationship as long as they 
can maintain fusion of the pictures. 
It does take a little effort, however, and 
this effort depends almost directly upon 
the amount of forescreen subject matter 
there is in proportion to that which is at, 
or behind the screen plane. It also in- 
creases rapidly as the proportional dis- 
tance out from the screen increases. 

Hofstetter 10 has shown that for most 
observers, fusion can take place with 



accommodation at distances comparable 
to those in an average theater, when 
image points are as close as 30 in. from 
the observer. Allowing a "factor of 
safety" of 2 as we did for the separation 
of background points, and again using 
a "close" viewing distance of 20 ft or 
240 in., we find that most observers will 
be able to fuse stereoscopic pictures 
satisfactorily if they do not come closer 
than f of the way out from the screen. 

How Far Forescreen Can 
Image Points Come? 

If there is so much difficulty with 
forescreen or forewindow subject matter, 
why bring image points forescreen at all? 
The answer is, of course, that only by 
doing so can the images be brought close 
enough to the observer to give the best 
effects obtainable with this medium. 
The "stage" between the screen and the 
observer is much nearer and therefore 
more "see-able" in many ways than that 
which extends back from the screen. 
Furthermore, forescreen subject matter 
comes out a proportionate distance to 
each observer, so that those in the back 
seats receive more of the effect a 
partial compensation for their added 
distance from the screen. 

On the other hand, most of the diffi- 
culties which have been mentioned can 
be controlled quite satisfactorily by 
observing a few simple rules, and by 
following the results of calculations based 
upon the theory which has already been 
developed. 

For example, we have already seen 
that any subject matter which is to be 
viewed for any period of time, or with 
any clarity, should not come closer 
than f or 0.75 of the way out from the 
screen. Actually the Research Council 
recommends use of an "0.8 near point" 
as the nearest any objects should be 
brought out. Even at this distance, 
viewing will be difficult and "stretch" 
will be apparent. Therefore for sus- 
tained pleasant viewing a closer limit is 
needed. 



Hill: Stereoscopic Photography 



483 




Fig. 12. Forescreen action area where window is at screen 
plane. Shaded area shows region in which forescreen action 
can take place without distortion or difficulties with the win- 
dow edges. Some care must be given that forescreen subject 
matter near top at center is not cut off unnaturally. 



Rule 7 recommended that no objects be 
brought closer than halfway from screen 
to observer, that is to the "0.5 near 
point." Experience has shown this 
to be a very sound recommendation, 
because within this limit psychological 
distortion seldom gives any trouble, 
and no noticeable strain occurs from ac- 
commodation-convergence breakdown . 
Under some conditions, with suitable 
subject matter, it is possible to have sus- 
tained, comfortable viewing at slightly 
greater ratios. This is particularly true 
if a forescreen window is used as dis- 
cussed later. However, as a general 
recommendation, the 0.5 near point pro- 
vides a safe limit which will insure satis- 
factory results. 

Recommended Forescreen Action Areas 

We now have the information needed 



to recommend suitable areas between 
the plane of convergence and the camera 
in which action can take place, or objects 
can be placed, and still give pleasing 
results when the pictures are projected 
on theater screens. 

In the first place, we must avoid 
having forescreen, or rather forewindow 
subject matter near the sides of the 
picture. Except for the very near seats, 
the lower edge of the window seems to 
give but little trouble in this respect, 
and objects can be brought forward in 
the center of the scene without the dis- 
tracting effects found at the sides. At- 
tention must be given the top edge, 
however, for if it cuts off objects which 
should appear to project into the audi- 
torium, the desired effect will certainly 
be lost. 

When the screen masking forms the 



484 



October 1953 Journal of the SMPTE Vol. 61 



CONVERGENCE 




&S NEAR POINT 



CAMERA 



Fig. 13. Forescreen action area where a forescreen window is 
used at the 0.5 near point. Shaded area shows region in which 
forescreen action can take place without distortion and without 
difficulties with window edges. 



window, the recommendation is that the 
main action in front of the camera be 
confined within a curved line as shown 
in Fig. 12, with the center at the 0.5 
near point, and the sides arcing back 
to the plane of convergence at the edges 
of the field of view. Projected objects, 
and other subject matter, used to pro- 
vide special effects, can be brought 
out to the 0.8 near point provided they 
are not held there for too long, and pro- 
vided of course that the inevitable dis- 
tortion will not be undesirable. 

When a forescreen window can be 
used, the foreground action area can 
take the form shown in Fig. 13. There 
is some increase in this area over that 
shown in Fig. 12, but this may be lost 
by the decrease in aperture size, and 
therefore in field of view, required to 
provide the window. 



Use of the "Near Point" Reference Lines 

In brief then, it is desirable to estab- 
lish on the set, two "near point" refer- 
ence lines. One of these will be at those 
positions which will appear to be 0.5 
of the way from the screen to each ob- 
server, and this will be the limit of any 
action or subject matter which is to be 
looked at for more than a few seconds at a 
time, or which is to be free from what we 
have termed psychological distortion. 
The other reference line should be at the 
0.8 near point, and nothing which is to 
be seen clearly should be allowed to come 
closer to the camera than this reference 
line. If some special effect requires 
that objects do come closer than this, it 
must be remembered that they will be 
very hard to look at and for many obser- 
vers will appear only as indistinct blurs. 



Hill: Stereoscopic Photography 



485 



V. CONCLUSIONS CONCERNING THE PRACTICABILITY OF THIS SYSTEM 



(a) The system proposed by the Re- 
search Council is comparatively simple 
and straightforward. To one un- 
acquainted with it, it may at first seem 
to be quite otherwise, but this is only 
because so many more factors can be 
taken into consideration and given proper 
treatment than can be treated in other 
systems. 

(b) There is plenty of allowance for 
psychological factors and for judgment 
on the part of the operator. For ex- 
ample, the factor G is determined upon 
psychological principles. The best 
values to use for a and p are a matter of 
judgment and experience. Neverthe- 
less, once these factors have been deter- 
mined properly, selection of a suitable 
interaxial distance is a simple, straight- 
forward calculation. 

(c) The system is flexible enough for 
use with any kind of shot. Intelligent 
treatment can be given close-ups, long 
telephoto shots, scenic vistas having great 
depth, and all the varied shots con- 
stantly occurring in everyday shooting. 
Provision is also made for taking good 
miniature shots and other special effects, 
and for suitably positioning titles, ani- 
mated cartoons and similar subject 
matter which is to appear in three di- 
mensions. 

(d) The system has been proved in 
practice. Several critical tests have 
been made comparing this system with 
other proposed bases for calculating 
these settings. In each case the Re- 
search Council proposals were demon- 
strated as much superior in their ability 
to give pictures which were natural 
and pleasing to the eye and which 
avoided most of the difficult seeing 
conditions so often encountered in three- 
dimensional pictures. 

This system therefore takes into ac- 
count the basic principles of physiological 
optics, and uses these to establish the 
best way of taking stereoscopic pictures 



so that they will appear as natural as 
possible when projected in the theater 
and viewed from various viewing posi- 
tions. In so doing, it uses principles 
which are known to give good results and 
which can be depended upon not to 
strain the eyes. Leading eye specialists 
have pointed out that the viewing of 
properly photographed three-dimen- 
sional pictures can actually be helpful 
to the eyes. We submit that pictures 
taken in accordance with the principles 
set forth here will have a maximum of 
third-dimensional effect, will have a 
pleasing balance between perspective 
and binocular depth, and will above all 
be easy and pleasing to look at. 

References 

1. Raymond Spottiswoode, N. L. Spottis- 
woode and Charles Smith, "Basic prin- 
ciples of the three-dimensional film," 
Jour. SMPTE, 59: 249-286, Oct. 1952. 

2. Lord Charnwood, An Essay on Binoc- 
ular Vision, Hatton Press Ltd., London, 
1950. 

3. Kenneth N. Ogle, Researches in Binocu- 
lar Vision, W. B. Saunders Co., Phila- 
delphia, 1950. Ch. 12. 

4. Rudolph K. Luneburg, "The metric 
of binocular visual space," J. Opt. Soc. 
Am., 40: 627-642, Oct. 1950. 

5. Walter C. Michels and Harry Helson, 
"Man as a meter," Physics Today, 6: 
4-7, Aug. 1953. 

6. Rudolph K. Luneburg, Mathematical 
Analysis of Binocular Vision, Princeton 
University Press, 1947. 

7. John T. Rule, "The geometry of 
stereoscopic projection," J. Opt. Soc. 
Am., 31: 325-334, Apr. 1941. 

8. John S. Norling, "The stereoscopic art," 
Jour. SMPTE, 60: 268-308, Mar. 1953. 

9. G. A. Fry and P. R. Kent, "The effects 
of base-in and base-out prisms on 
stereo-acuity," Am. J. Optom. Mono- 
graph, 4: Dec. 1944. 

10. H. W. Hofstetter, "Zone of clear single 
binocular vision," Am. J. Optom. 
Monograph, W: Aug. 1945. 



486 



October 1953 Journal of the SMPTE Vol. 61 



Optical Techniques for Fluid Flow 



By NORMAN F. BARNES 



In flow studies of liquids and gases, the velocity, pressure, density and tempera- 
ture of the moving fluid can be obtained through the use of schlieren, shadow- 
graph and interferometer techniques. A basic optical and photographic de- 
scription is given of the three systems, and a fundamental application com- 
parison is made. 



I 



N THE STUDY of the flow of fluids, both 
liquids and gases, it is necessary to know 
the distribution of velocity, pressure, den- 
sity or temperature of the moving fluid. 
In many cases it is possible to obtain 
much information by passing a beam of 
light through the flow and observing the 
effect of the fluid upon the light beam. 
The variations in density throughout the 
flow produce corresponding changes in 
the index of refraction of the fluid, these 
in turn causing variations in the beam 
of light. These latter variations can 
then be made visible on a screen or re- 
corded on a photographic plate. 

Though optical methods are sensitive 
only to density variations, the related 
flow characteristics of velocity, pressure 
and temperature can usually be calcu- 
lated through the application of the laws 
of fluid mechanics, perhaps supple- 
mented by certain nonoptical measure- 
ments to define the state of the fluid. 
There are three main advantages of an 



Presented on October 8, 1952, at the Soci- 
ety's Convention at Washington, D.C., by 
Norman F. Barnes, General Electric Co., 
1 River Rd., Schenectady 5, N.Y. 
(This paper was received March 30, 1953.) 



optical approach to the study of fluid 
flow: (1) the light will not distort or re- 
tard the flow; (2) measurements can be 
made over the entire field simultane- 
ously; and (3) the measurements are 
free from inertia effects, such as are pres- 
ent if smoke or other particles are in- 
duced into the flow to make the char- 
acteristics of the latter visible. It be- 
comes the object of the optical analysis, 
then, to analyze the variations imparted 
to the beam of light in order to find the 
corresponding changes in density of the 
fluid which produced such variations. 

In Fig. 1, a light ray is shown entering 
a disturbing medium. After it emerges, 
it continues toward the screen, striki: g 
it at a point P ' rather than at the point P 
where it would have arrived had not the 
disturbance been present. The angle 
between the original direction of the 
light ray and its final direction after pass- 
ing through the disturbance is repre- 
sented by angle A. Since the velocity of 
light changes with the density of the 
medium in which it travels, the time of 
arrival of the ray at point P (time t) is 
different from the arrival time at point 
P' (time t')- There are, therefore, three 



October 1953 Journal of the SMPTE Vol. 61 



487 



LIGHT RAY 




DISTURBANCE 



P(t) 



P'(t') 



SCREEN 
Fig. 1. Light ray entering a disturbing medium. 



SPARK GAP 



U 

n 




PHOTOGRAPHIC 
FILM 



Fig. 2. Shadowgraph system. 



variations or results of the disturbance 
which can be used as the basis of optical 
measurement. These are the displace- 
ment of point P to P', the deflection or 
angle A and the difference in arrival 
time t' t. Each of these three vari- 
ations forms the basis of a different type 
of optical measurement. Thus, the 
shadowgraph method records the dis- 
placement of the ray while the schlieren 
method is based on the angular deflec- 
tion of the ray. Finally, the interferom- 
eter method is based on the difference 
in arrival time between the disturbed 
and undisturbed rays. Each of these 
methods will be described, showing the 
type of equipment used and the nature 
of the results produced. 

Figure 2 illustrates a shadowgraph 
system. A point source of light such as 
a spark gap illuminates a test area, the 
light then being allowed to fall upon a 
screen or photographic plate. If the 
rays of light do not undergo any devi- 
ation in the test area, the screen will be 
uniformly illuminated. However, if a 
disturbance is produced, the rays of light 
which are affected will undergo a devi- 
ation causing a corresponding change in 



the illumination on the screen. Thus, 
referring to Fig. 3, the rays which nor- 
mally would have reached the screen at 
area A have been refracted to area B, 
producing a lowering of illumination at 
A and an increase at B. 

Since the angular deviations of the 
rays are proportional to the first deriva- 
tive of density perpendicular to the ray 
of light, and since the variation of illumi- 
nation on the screen is proportional to 
the derivative of the deviation, the final 
variation of the light on the screen is pro- 
portional to the second derivative of the 
density in the disturbance. Conse- 
quently, the shadowgraph method is most 
useful in the study of abrupt variations 
in density such as those which occur in 
the presence of shock waves. For slow 
and continuous variations in density, the 
shadowgraph system becomes insensitive. 

A spark gap, using either zinc or 
magnesium electrodes, has proved to be 
useful for shadowgraph photography. 
The primary reason for this is that the 
circuit characteristics for a spark dis- 
charge are such that they permit an ex- 
tremely short time duration of the flash 
as compared with that produced by dis- 



488 



October 1953 Journal of the SMPTE Vol. 61 




X 

DISTURBANCE 



SCREEN 



Fig. 3. Shadowgraph effect. 




HIGH VOLTAGE 
CAPACITOR 



Fig. 4. Shadowgraph spark source. 



charge lamps. By using the spark source 
shown in Fig. 4 effective photographic 
exposure times of 0.2 /-isec have been 
made. That such an extremely short 
time could be obtained is due largely to 
keeping the inductance of the discharge 
circuit to an absolute minimum. Prior 
to the discharge the double-pointed elec- 
trode shown above the capacitor is al- 
lowed to "float" electrically, the gap 
separations being such that the high- 
voltage capacitor will not discharge 
itself. When the double-pole, double- 
throw switch is thrown, a positive voltage 



is applied to the thyratron tube so that it 
becomes conducting, therefore lowering 
the double-pointed electrode to ground 
potential. A spark then jumps from the 
high-voltage terminal to this electrode, 
thereby raising its potential to the maxi- 
mum and thus allowing the spark to 
jump to the ground terminal on the 
capacitor. The two spark gaps are 
lined up in the direction of the arrow, 
producing the effect of a single source as 
seen from the disturbance. The entire 
discharge circuit consists of only several 
inches of heavy conductors. 



Barnes: Optical Techniques 



489 




Fig. 5. Bullet discharged from 
the muzzle of a gun. 

The results which have been obtained 
with the General Electric spark unit are 
illustrated in Fig. 5. Here the discharge 
energy was obtained from a 0.12 juf 
(microfarad), low inductance capacitor 
charged to 10,000 v. The picture shows 
a bullet being discharged from the 
muzzle of a gun. The many curved 
lines in the picture are sound waves 
generated when the compressed gases 
expand from the muzzle. The bullet is 
centered in the air that it pushes out of 
the barrel by its piston action. The 
expanding, turbulent gas behind the 
bullet gives it its acceleration. 

The spark gap was placed approxi- 
mately 1 5 ft to one side and perpendicu- 
lar to the path of the bullet, while the 
film was placed at a distance of 18 in. to 
the other side and parallel to the bullet 
path. 

Figure 6 shows a shadowgraph picture 
of supersonic flow past a multiple shock 
diffuser central body, for a Mach number 
of 2.7 as photographed by the NAGA 
(National Advisory Committee on Aero- 
nautics) laboratories. 

Although the sensitivity of a shadow- 
graph system increases directly with the 
distance between the disturbance and 
the screen or photographic plate, a point 
is soon reached beyond which the reso- 
lution of the image rapidly deteriorates ; 
thus, a compromise must be made be- 



Fig. 6. Shadowgraph picture of super- 
sonic flow past a multiple shock 
diffuser central body for a Mach 
number of 2.7 



tween sensitivity and image quality. 
The size of the discharge spark will also 
have an important bearing upon the 
image quality of the shadowgraph pic- 
ture. If a relatively large spark is used, 
it will have to be placed farther away 
from the disturbance in order to act 
effectively as a point source. Good re- 
sults can be obtained using photographic 
films having moderate or high speeds. 
In general the extremely short exposure 
time produces a lower-than-normal con- 
trast upon development so that it is ad- 
visable to use higher contrast developers 
with times ranging from normal to three 
times normal. 

Figure 7 is an NACA shadowgraph 
picture of rather unusual interest show- 
ing the shock- wave formation on a P51 
airplane in flight. 85 Figure 8 shows how 
this picture was produced using the 
parallel rays from the sun as the light 
source. The increasing strength of the 
shock wave going nearer to the upper sur- 
face of the airfoil acts as a prism to de- 
flect the rays of light as shown. 

While the great advantage of the 
shadowgraph method is the extremely 
simple arrangement which requires no 
lenses or mirrors, the system is far too in- 
sensitive for many applications. A small 
displacement which would be insignifi- 



490 



October 1953 Journal of the SMPTE Vol. 61 




Fig. 7. Shadowgraph picture showing shock-wave formation on a 
P51 airplane in flight. 



cant in a shadowgraph system could pro- 
duce a very noticeable effect in a schlie- 
ren system. The operation of the schlie- 
ren method can best be described with 
reference to Fig. 9. Light from an illu- 
minated pinhole or slit S is allowed to fall 
upon lens LI and be converged to the 
image point at P. A lens L2 is used to 
focus upon the screen the striation or dis- 
turbances produced in the flow placed 
immediately to the right of lens LI. A 
knife edge E is moved laterally across the 
image point until all the rays passing 
through that image are obscured. The 
field as viewed upon the screen will then 



be uniformly dark. If a light ray in 
passing through the disturbance is re- 
fracted upward, this ray will no longer 
pass through the image point P but will 
travel above it. Hence this ray will not 
be obscured by the knife edge but will 
pass on to the screen, illuminating a 
point corresponding to the location of 
that particular part of the disturbance. 
Thus, for every point in the disturbance 
for which a similar refraction takes place, 
there will be a corresponding point illu- 
minated on the viewing screen. The 
composite of all such points forms the 
image of the phenomenon to be investi- 
gated. 



Barnes: Optical Techniques 



491 



Low density 
medium 



-*- Leading edge 




High density 
medium 



Upper surface 
of airfoil 



Fig. 8. Chordwise cross section showing production of a shock wave 
using parallel rays of the sun as a light source. 




SCREEN 



Fig. 9. Operation of the schlieren method. 



If the bending in the disturbance is 
downward the rays will be caught by the 
knife edge, and the corresponding points 
on the viewing screen will be dark. In 
making the lateral adjustment of the 
knife edge when no disturbance is pres- 
ent, it is desirable to allow some of the 
rays to pass over the knife edge in order 
to produce a uniformly low background 
illumination. The presence of this back- 
ground makes it possible to see more 
clearly in silhouette form the objects 
used in producing the air-flow phe- 
nomena. Thus, referring to Fig. 10, a 
downward deflection of rays darkens the 
screen while an upward deflection in- 
creases the screen illumination. 



The field lenses used in the schlieren 
systems must be well corrected lenses, 
particularly from the standpoint of 
spherical aberration. Otherwise, it will 
not be possible to obtain a uniform 
brightness across the field projected upon 
the viewing screen. Also, if large 
amounts of chromatic aberration are 
present, the striation image on the view- 
ing screen will not be sharp. The glass 
of the lenses must be of the finest optical 
quality and free from scratches so that 
the lenses will be striation free. Other- 
wise, any striae in the field lenses will be 
superimposed upon those which are being 
investigated. 

If a large diameter field is required, it 



492 



October 1953 Journal of the SMPTE Vol. 61 



LENS 




SAMPLE 



PARTIAL CUTOFF 
(MAXIMUM SENSITIVITY) 




82 



B2 



I 



SAMPLE 



Fig. 10. Schlieren knife edge adjustment. 



LIGHT SOURCE 




KNIFE EDGE 



SCREEN 
Fig. 11. Double concave mirror schlieren system. 



is exceedingly difficult, if not practically 
impossible, to obtain well-corrected 
lenses. For that reason it is highly desir- 
able to use concave mirrors in place of 
the lenses. The use of such mirrors has 
many advantages. Since first-surface 
mirrors are used, the optical quality of 
the glass does not affect the striation field. 
Furthermore, chromatic aberration is 



eliminated. Since the mirror surface 
can be parabolized, it is possible to ob- 
tain large mirrors which are well cor- 
rected for spherical aberration. 

The double concave-mirror system 
shown in Fig. 11 has proved to be most 
satisfactory for a wide variety of appli- 
cations. 178 Here the light passing 
through the investigation region has 



Barnes: Optical Techniques 



493 





Fig. 12. Mazda Type B-H6 lamp with its air-cooling nozzle. 



been made parallel by the first parabolic 
mirror. Since the sensitivity of the sys- 
tem is independent of the location of the 
disturbance between the two parabolic 
mirrors, one can simultaneously use the 
second parabolic mirror to focus the 
disturbance upon the screen as well as to 
converge the light to the source image 
point at the knife edge. However, be- 
cause of aberrations of the system, a 
sharper image will be produced on the 
screen if a lens is used behind the knife 
edge for focusing purposes. In order 
that the system be effectively coma free, 
the light source and the knife edge must 
be on opposite sides of the common 
mirror axis. The equality of the angles 
from the source to the common mirror 



axis is required in order to avoid coma, 
while the size of the angles determines the 
amount of astigmatism which is intro- 
duced. Either of these aberrations will 
cause a poor knife-edge image of the 
light source, resulting in uneven sensi- 
tivity over the field. 

One of the most useful light sources for 
schlieren systems is the Mazda Type 
B-H6 lamp. This is a 1000-w, high- 
pressure mercury lamp used with air 
cooling. A picture of this lamp along 
with its air-cooling nozzle is shown in 
Fig. 12. By the, nature of the lamp itself 
this light source is a natural slit source 
whose dimensions are approximately 1 
by 25 mm. For high sensitivity for 
photbgraphic recording, slits as small as 




FLASH TUBE 
Fig. 13. Schlieren source. 



SLIT 



494 



October 1953 Journal of the SMPTE Vol. 61 





Fig. 14. Schlieren photograph of a jet showing sound waves and 

the reflection of one from a plate at the top, using a B-H6 lamp 

as a flash source. 





Fig. 15. Schlieren photograph of a jet with wings swept back at a rakish angle. 

Barnes: Optical Techniques 495 



WTC 





airfoil 





airfoil 



Fig. 16. Aerodynamic phenomena at subsonic, transonic and supersonic 
speeds for both subsonic and supersonic airfoil. 



10 by 40 mils are placed in front of the 
light source. 

The lamp can be operated continu- 
ously for visual observation or it can be 
flashed for taking instantaneous pictures 
effectively. When a 2-juf capacitor 
charged to 2000 v is discharged through 
the lamp, the effective photographic ex- 
posure time will be about 3 /zsec. 

A flashtube such as the FT 230 can 
also be used as the source of short- 
duration light. As shown in Fig. 13, 
light from the discharge gap is focused 
on a slit, which becomes the effective 
source for the schlieren system. For 
continuous observation and alignment 
purposes, a ribbon-filament, tungsten 
lamp is placed on the opposite side of the 
flashtube from the slit and is focused be- 
tween the electrodes of the flashtube by 
an auxiliary lens. In this way any ad- 
justment made with the tungsten lamp 
will be correct for the flashtube. 

Figure 14 is a schlieren photograph of 
a jet, showing sound waves and the re- 
flection of one from a plate at the top, 



using the B-H6 lamp as a flash source. 
Further illustration showing the appli- 
cation of schlieren techniques is seen in 
the NAGA photographs of Figs. 15 and 
16. The former points out the advan- 
tages that can be obtained by sweeping 
the wings of an airplane back at a rakish 
angle. With no sweepback, as in the 
picture at the left, a very intense shock 
wave is formed, represented by the black 
region immediately ahead of the wing. 
When the wing is swept back, the shock 
wave is also swept back with an accom- 
panying reduction in intensity and hence 
a reduction in the wing drag. Figure 16 
shows aerodynamic phenomena at sub- 
sonic, transonic and supersonic speeds 
for both subsonic and supersonic airfoil. 
It is interesting to note the tremendous 
disturbance produced in taking a sub- 
sonic airfoil through transonic region to 
supersonic speeds. 

In a schlieren system the deviation of 
the rays, and hence the screen illumina- 
tion, is proportional to the first derivative 
of the density variation. The sensitivity 



496 



October 1953 Journal of the SMPTE Vol. 61 




Fig. 17. Shock wave and the explosive products which come from a 
dynamite cap. 



of the system is proportional to the focal 
length of the mirrors in the system al- 
ready described and inversely propor- 
tional to the width of the light-source 
image perpendicular to the knife edge. 
Optical aberrations, diffraction at the 
light-source image and the necessity for 
satisfactory image brightness impose 
limits upon the possible sensitivity. 

High-speed photographic techniques 
have been developed for the study of 
transient phenomena in supersonic flow. 
Bradfield and Fish 56 have developed a 
repetitive spark light source capable of 
producing bursts of light for taking up to 
250 schlieren photographs at a frequency 
as high as 16,000 pictures per second. 
With approximately 20-msec bursts of 
the high-speed sparks and effective expo- 
sure times of 2 to 4 /xsec this technique has 
proved to be very useful in studying non- 
stationary supersonic flow problems. 

A double-flash, high-speed photo- 



graphic technique has been developed by 
Edgerton 187 for either the schlieren or 
shadowgraph study of transient shock 
waves or rapidly moving objects. Figure 
17 shows the shock wave and the explo- 
sive products which come from a dyna- 
mite cap. The first flash from the spark 
unit was triggered by the light from the 
explosion, and the second flash was timed 
to occur approximately 4 //sec later dur- 
ing which time the shock wave traveled 
about 0.4 in., corresponding to an aver- 
age velocity of 8,000 ft/sec. The expo- 
sure time is 0.2 //sec. 

In the conventional schlieren system 
the density gradients at all points along 
the path of a light ray contribute to the 
resultant image. In a strictly two- 
dimensional flow no complications arise. 
However, from practical considera- 
tions the flow may be influenced by 
the boundary layer present on the glass 
walls as well as by waves reflecting from 



Barnes: Optical Techniques 



497 



FOCUSING LENS 



REFRACTING OBJECT 




IMAGE 



Fig. 18. Focusing effect with multiple sources. 



these walls, so that the flow is actually 
three-dimensional. Consequently, one 
is forced to try to interpret three-dimen- 
sional flow with an apparatus which 
gives an integrated effect of such phe- 
nomena. 

In order to obviate such difficulties 
Kantrowitz and Trimpi 63 have designed 
a schlieren system which can be focused 
at any plane in the test section. In order 
to be able to focus a system in this man- 
ner one must have either divergent or 
convergent light paths, since only by 
this means can the disturbances at vari- 
ous distances be singled out. Thus, 
referring to Fig. 18, if two sources and 
corresponding knife edges are used, the 
focusing lens will focus just the refracting 
object on the screen. Any other points 
will not be superimposed on the screen 
and will therefore be blurred. In actual 
practice, fifty or more slits are used along 
with their corresponding knife edges. 
Both the source-slit plate and the knife- 
edge plate are made photographically. 
Each of these sources and its correspond- 
ing knife edge acts as an individual 
schlieren system. Since the beams will 
only superimpose for a single plane of the 
disturbance, two-dimensional investi- 
gation of sections of a three-dimensional 
flow can actually be made. Burton 67 ' ^ 
has shown that the use of such grids of 
pinholes or lines permits the use of large 
optical fields which are not limited by the 
physical size of the lenses or mirrors used. 



The use of schlieren technique becomes 
extremely difficult or even useless when 
the density of the flow is decreased to 
very low values. It has been shown that 
certain gases such as nitrogen are capable 
of emitting light for relatively long pe- 
riods of time after they have been excited 
electrically. This phenomenon of per- 
sistence of luminescence is referred to as 
afterglow. Since the intensity of the 
afterglow increases with increased den- 
sity of the glowing gas, a method is pro- 
vided to make the flow disturbances pro- 
duce their own light so that they may be 
photographed, the resulting picture 
being similar to a schlieren photograph 
in appearance. A schematic diagram 
of this afterglow equipment as developed 
by Williams and Benson 79 is shown in 
Fig. 19. Nitrogen from the supply tank 
is excited by means of high voltage and 
then drawn into the test chamber where 
its glow is photographed. Figure 20 
shows the afterglow pattern over a 15, 
double-wedge model at a stagnation pres- 
sure of 60 mm of mercury and an indi- 
cated Mach number of 2.6. 

Recalling again the third type of 
optical measurement dealing with the 
difference in arrival time between a dis- 
turbed and an undisturbed ray, the 
change in the velocity of the light can 
easily be measured by comparing the 
beam of light which has passed through 
the test section with a similar beam 
which has passed through a stationary or 



498 



October 1953 Journal of the SMPTE Vol. 61 




Fig. 19. Afterglow apparatus. 



undisturbed field. Since light travels 
in a wave motion, these two beams of 
light can then be combined in such a 
way that the peaks of the waves of each 
alternately add and subtract to produce 
interference fringes or lines of alter- 
nately weak and strong intensity. 

An interferometer consists essentially 
of a light source, a means of splitting the 
light into two beams, one of which passes 
through the test section, a means of re- 




Fig. 20. Afterglow pattern over a 16 
double-wedge model at a stagnation 
pressure of 60 mm of mercury and an 
indicated Mach number of 2.6. 



combining the two beams and a screen or 
camera for observing or recording the 
patterns. Thus, referring to Fig. 21, the 
light from the source is made into a 
beam of parallel rays by lens LI . When 
these rays reach the beam-splitting plate 
PI, part of the light is reflected to mirror 
Ml. The part that is transmitted is 
directed through the test area by means 
of mirror M2. The two beams are then 
combined by means of the plate P2, 
those rays coming from Ml being par- 
tially transmitted by the plate and those 




f==\ 



Fig. 21. Mach-Zehnder Interferometer. 



Barnes: Optical Techniques 



499 



*- A -* 



ORIGINAL 
PATTERN 



SHIFTED 
PATTERN 



Fig. 22. Interference fringe shift. 

coming from M2 being partially re- 
flected. The camera lens then focuses 
the light upon the photographic plate. 



If the optical components are essen- 
tially perfect and if the optical path 
lengths in the two halves of the system are 
identical over the entire field for no dis- 
turbance, then the field of view will be 
uniformly illuminated and the so-called 
infinite width fringe will be produced. 
If one of the beam-splitting plates 
or one of the mirrors is rotated 
slightly, interference fringes will be 
formed whose lines are equidistant and 
parallel to the axis of rotation of the 
mirror or plate. At each point where 
the optical paths in the two halves of the 




Fig. 23. Interferometer photograph of supersonic flow past a sphere in a 
free jet at Mach number 1.6. 



500 



October 1953 Journal of the SMPTE Vol. 61 



system differ by an odd number of half- 
wavelengths of the light used, the two 
parts of this ray will cancel each other 
and thereby form a dark zone. 

The outstanding characteristic of the 
interferometric method of analysis is its 
ability to provide quantitative data. 
Interference pictures can be evaluated to 
show the distribution of density through- 
out an entire flow field. Though the 
analysis of interference photographs of 
axially symmetric flow involves rather 
difficult integral equation calculations 124 , 
the evaluation is relatively simple for 
two-dimensional flow. In this latter 




Fig. 24. Flow past cascade of 
turbine blades. 



Fig. 25. Interference pic- 
ture of temperature field 
formed by natural con- 
vection inside and out- 
side a heated, hollow 
cylinder. 




Barnes: Optical Techniques 



501 




Fig. 26. Interferometer pic- 
ture showing isothermal 
lines inside and outside a 
heated, hollow cylinder. 



case, the change in density at a particular 
point in the flow is directly proportional 
to the fringe shift from the undisturbed 
pattern. Thus, referring to Fig. 22, let 
us assume an undisturbed pattern to have 
fringes separated by the distance A. 
If the disturbance then produces a shift 
D in the fringes, then the value of the 
corresponding changes in density can be 
computed so that it is possible to determine 
the density values throughout the entire 
field. The density change is directly 
proportional to the fringe shift D. 
Means of evaluating interferometer pic- 
tures are suggested by Ashkenas and 
Bryson 148 . 

Figure 23 is a NAG A interference pic- 



ture of the supersonic flow past a sphere 
in a free jet (Mach number 1.6). The 
undisturbed lines are shown at the left of 
the picture. In the right part of the pic- 
ture the fringes are distorted by the vary- 
ing retardation experienced by the light 
when traveling through the disturbance. 
Since the interferometer system is sensi- 
tive to infinitesimally small deviations of 
the light path, the method is particularly 
useful in relatively large regions of con- 
tinuous and small variations in density. 
Where these variations are discontinuous 
or abrupt, interpretation of the picture 
becomes difficult. The most useful in- 
formation is obtained when the inter- 
ference fringes intersect the object sur- 



502 



October 1953 Journal of the SMPTE Vol.61 



face at right angles. In order to accom- 
plish this result the fringes can be 
oriented in any direction by proper ro- 
tation of the two beam-splitting plates 
and the two mirrors. An illustration of 
this, Fig. 24, shows the flow through a 
cascade of turbine blades. 

Figure 25 shows an interference pic- 
ture of the temperature field formed by 
natural convection inside and outside a 
heated, hollow cylinder. The displace- 
ment of the fringes can be interpreted, by 
calculation, in terms of air temperature. 
Thus the locus of the points of equal 
fringe shift will be an isothermal line. 
If, for the initial, undisturbed condition, 
the interferometer is adjusted for a single 
or infinite width fringe, each fringe in the 
resulting picture when the cylinder is 
heated represents an isothermal line it- 
self as shown in Fig. 26. The change in 
temperature from one fringe to the next 
is approximately 2 C. 

The outstanding advantages of the 
interferometric method of analysis are 
the extreme sensitivity which can be ob- 
tained and the relative ease of obtaining 



quantitative information. Together the 
shadowgraph, schlieren and interfero- 
metric techniques are playing an impor- 
tant part as a powerful tool in the study of 
high-speed, aerodynamic phenomena. 

The author wishes to take this oppor- 
tunity to express his sincere gratitude to 
Miss Leonore McAlonen and Mr. 
Frederick Thurston for their assistance 
in preparing the following bibliography. 
While a few of the earlier works in the 
fields listed are included in the bibliog- 
raphy, most of the literature referred to 
has been published in more recent times. 
Where an article refers to two or more of 
the three basic types of optical systems 
described or where an article describes a 
different type of system, such an article 
is listed under the heading of "General." 
The bibliography is by no means com- 
plete, and there are excellent references 
which could be added, many of which 
corresponding articles have a security 
classification. However, it is hoped that 
this bibliography as it is will be of valu- 
able help to the many workers pioneering 
in this field. 



BIBLIOGRAPHY 



Schlieren Application 



1. Allen, H. S., "The photography of 
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2. Barnes, G. M., "Supersonic wind 
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3. Boelter, L. M. and Cherry, V. H., 
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4. Bogdonoff, S. M., "NACA cascade 
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5. Busemann, Adolf, "The drag problem 
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6. Granz, G. and Barnes, E., "High- 
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7. Dhawan, S. and Roshko, A., "A flex- 
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8. Feng, K. I., "Schlieren observation in 
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9. Garside, Hall and Townend, "Flow 
states in emergent gas streams," 
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10. Gawthrop, D. B., "Application of the 
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11. Gawthrop, D. B., "Propagation tests 
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12. Gothert, B., "High-speed measure- 



Barnes: Optical Techniques 



503 



merits on symmetrical bodies," DVL 
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13. Hertzberg, A. and Kantrowitz, A., 
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14. Hertzberg A., "A shock tube method 
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15. "High speed motion picture photog- 
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16. Humphrey, R. H. and Jane, R. S., 
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18. Klug, H., "Experimentelle Unter- 
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19. Liepmann, H. W., "The interaction 
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20. Liepmann, H. W. and Ashkenas, 
H. I., "Shock wave oscillations in 
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21. MacGregor, G. W., "The formation of 
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22. Nadai, A., "Phenomenon of slip in 
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23. Osterstrom, G. E., "Knocking com- 
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24. Payman, W., "The detonation wave 
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25. Payman, W. and Robinson, H., "The 
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26. Payman, W. and Shepherd, W. G., 
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27. Payman, W. and Shepherd, W. G., 
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Proc. Roy. Soc., A186: 293, 1946. 



28. Payman, W. and Titman, "The initia- 
tion of detonation in mixtures of 
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Soc., A152: 418, 1935. 

29. Payman, W. and Woodhead, D. B., 
'The wave speed camera and its ap- 
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in flight," Proc. Roy. Soc., 132: 200-213 
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30. Pearce, R. B., "Supersonic tunnel for 
missiles," Aviation Week, 49: 22, Aug. 
23, 1948. 

31. Philpot, J. St. L., "Direct photog- 
raphy of ultracentrifuge sedimentation 
curves," Nature, 141: 283, 1938. 

32. Prandtl, L., "Neue Untersuchungen 
iiber die stromende Bewegung der 
Gase und Dampfe," Physik. Z., 8: 23, 
1907. 

33. Rothrock, A. M. and Spencer, R. G., 
National Advisory Committee of Aero- 
nautics 24th Annual Report, 213, 1938. 

34. Schrott, Carl, "Schlieren cinematog- 
raphy," Die Kinotechnik, 12: 40, 1930. 

35. Shepherd, W. G., "The ignition of fire 
damp by explosives; a study of the 
process by schlieren methods," Bur. 
Mines Bull., No. 354, 1932. 

36. Stack, John, "The compressibility 
burble," NACA TN543, Oct. 1935. 

37. Stack, John, "Compressible flows in 
aeronautics," J. Aeronaut. Sci., 12: 127, 
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38. "Supersonic wind tunnel," Automotive 
Industries, July 15, 1947. 

39. Tawil, E. P., "Ultrasonic standing 
waves made visible in a gas by 
schlieren method," Comptes Rendus, 
191: 92, 1930. 

40. Tawil, E. P., "Observation methods 
for non-stationary sound waves," 
Comptes Rendus, 191: 998, 1930. 

41. Tiselius, A., "A new apparatus for the 
electrophoretic analysis of colloidal 
mixtures," Trans. Faraday Soc., 33: 
524, 1937. 

42. Tiselius, A., "Schlieren method used 
to observe electrophoresis," Trans. 
Faraday Soc., 33: 524, 1937. 

43. Tiselius, A., Pedersen and Eriksson- 
Quensel, "Observation of ultracentrif- 
ugal sedimentation by Toepler 
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44. Toepler, A., "Observations of the 



504 



October 1953 Journal of the SMPTE Vol. 61 



singing flame by the schlieren appar- 
atus," Ann. d. Physik und Chemie., 128: 
126, 1866. 

45. Toepler, A., "Optical studies by the 
schlieren method of observation," 
Ann. d. Physik und Chemie., 131: 33, 
1867. 

46. Toepler, M., "Neue einfache Ver- 
suchsanordnung zur bequemen sub- 
jektiven Sichtbarmachung von Fun- 
kenschallwellen nach der Schlieren- 
methode," Ann. d. Physik, 27: 1043, 
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47. Towend, H. C., "Statistical measure- 
ments of turbulence in the flow of air 
through a pipe," Proc. Roy. Soc., A145: 
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48. Townend, H. C., "A method of air 
flow cinematography capable of quan- 
titative analysis," J. Aeronaut. Sci., 3: 
343, 1936. 

49. Townend, H. C., "Visual and photo- 
graphic methods of studying boundary 
layer flow," Aeronaut. Res. Comm. 
Great Brit. R & M, #1803, 1937. 

50. Turner, E. B., "Supersonic wind tun- 
nel schlieren system," Air Tech. 
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51. Wood, R. W., "Photography of sound 
waves and the kinematographic dem- 
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wave fronts," Phil. Mag., 50: 148, 
1900. 

52. Wood, R. W., "On the propagation 
of cusped waves and their relation to 
the primary and secondary focal 
lines," Phil. Mag., 52: 589, 1901. 

Schlieren Equipment 

53. Bailey, D. Z., "Design and operation 
of schlieren system," Gas Turbine 
Laboratory, M.I.T., unpublished re- 
port. 

54. Barnes, N. F. and Bellinger, S. L., 
"Analyzing airflow," G. E. Rev., Dec. 
1944. 

55. Barry, F. W. and Edelman, G. M., 
"An improved schlieren apparatus," 
J. Aeronaut. Sci., 15: 364, 1948. 

56. Bradfield, W. S. and Fish, W. Y., "A 
high-speed schlieren technique for 
investigation of aerodynamic tran- 
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57. Burton, Ralph A., "A modified 



schlieren apparatus for large areas of 
field," J. Opt. Soc. Am., 39: 907, 1949. 

58. Burton, Ralph A., "Notes on the 
multiple source schlieren system," 
J. Opt. Soc. Am., 41: 858, 1951. 

59. Fish, R. W. and Parnham, K., 
"Focussing schlieren systems," Air 
Tech. Intelligence, 101828, 1950. 

60. Hartmann, Julius, "The acoustic, air- 
jet generator," Ingeniorvidenskabelige 
Skrifter (Acad. Tech. Sci., Copen- 
hagen), no. 4, 1939. 

61. Herrington, R., "Design and con- 
struction of schlieren photography 
equipment," Rensselaer Polytechnic 
Institute, 1947. 

62. Hett, J. H., "High speed stereoscopic 
schlieren system," Jour. SMPTE, 56: 
214, 1951. 

63. Kantrowitz, Arthur and Trimpi, 
R. L., "A sharp-focusing schlieren 
system," J. Aeronaut. Sci., 17: 311, 
1950. 

64. Liepmann, H. W., "The 2" x 20" 
transonic wind tunnel," Final Re- 
port for Supplement Agreement, No. 1 
(S-4843) to Contract No. W 33-038 
with A.T.S.C., Wright Field, 1945. 

65. Mortensen, T. A., "An improved 
schlieren apparatus employing mul- 
tiple slit-gratings," Rev. Sci. Instr., 21: 
3, 1950. 

66. Prescott, R. and Gayhart, E. L., ''A 
method of correction of astigmatism 
in schlieren systems," J. Aeronaut. Sci., 
18: 69, 1951. 

67. Townend, H. C., "Improvements in 
the schlieren method of photography," 
J. Sci. Instr., 11: 184, 1934. 

Schlieren Theory 

68. Gayhart, E. L. and Prescott, R., 
"Interference phenomenon in the 
schlieren system," J. Opt. Soc. Am., 
39: 546, 1949. 

69. Lamia, E., "Uber den Strahlengang 
bei Schlierenaufnahmen von ein- 
fachen ebenen Stosswellen," Inst. 
f"r Gasdynamik, Oct. 1944. 

70. Report on the Second Conference of Fluid 
Dynamics at Princeton, 1946, published 
by Navy Department, Bureau of Ord- 
nance. 

71. Rutkowski, J., "The schlieren method 
in flow observation of rarefied gases," 
Air Tech. Intelligence, 32955. 

72. Schardin, H., "'Das Toeplersche 



Barnes: Optical Techniques 



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Schlierenverfahren," V.D.I. For- 
schungsheft 367, Berlin 1934. 

73. Schardin, H., "Toepler's schlieren 
method basic principles for its use 
and quantitative evaluation," (trans- 
lation of original paper) Air Tech. 
Intelligence, 22472. 

74. Se vault, A., "Phenomenon of electric 
in supersonic nozzle," Comptes Rendus 
225, #17, Oct. 27, 1947. 

75. Shafer, H. J., "A physical optic analy- 
sis of the schlieren method," Phys. 
Rev., 75: 1313, 1949. 

76. Straubel, R., "Dioptrik in Medien 
mit kontinuierlich variablem Bre- 
chungsindex," Handbuch d. Physik, 6: 
485, 1906. 

77. Taylor, H. G. and Waldran, J. M., 
''Improvements in the schlieren 
method," J. Sci. Instr., 10: 378, 1933. 

78. Toepler, A., Observation on a New Opti- 
cal Beam, Bonn, 1864. 

79. Williams, T. W. and Benson, J. M., 
"Preliminary investigation of the use 
of afterglow for visualizing low-den- 
sity compressibility flows," NACA 
U3715, Feb. 1949. 

80. Wood, R. W., "Photography of 
sound waves by the schlieren 
method," Phil. Mag., 48: 218, 1899; 
50: 148, 1900. 



Shadowgraph Photography 

81. Barg, J., "Anyone can make photo- 
grams," Am. Phot., 44: 49, 1950. 

82. Bull, G. V., "Investigation into the 
operating cycle of two-dimensional 
supersonic wind tunnel," J. Aeronaut. 
Sci., 19: 609, 1952. 

83. Charters, A. G. and Thomas, R. N., 
"Spark photography of 9 /ie" diam- 
eter spheres," J. Aeronaut. Sci., 72: 468, 
1945. 

84. Clark, J. C., "Spark photographic 
techniques at the applied physics lab. 
at Tokyo Imperial University," Dec. 
1945. 

85. Cooper, G. E. and Rothert, G. A., Jr., 
"Visual observations of the shock 
wave," NACA RM No. A8C25, 1948. 

86. Cranz, C., Lehrbuch der Ballistik, 2, 
193; 3, 271; Julius Springer, Berlin, 
1926. 

87. Cranz, C. and Glatzel, B., "Die Aus- 
stromung von Gasen bei hohen An- 



fangsdrucken. I. Teil," Ann. a. 
Physik, 43: 1186, 1914. 

88. Cranz, C. and Koch, R., "Uber die 
explosionsartige Wirkung moderner 
Infanteriegeschosse," Ann. d. Physik, 
3: 247, 1900. 

89. Emden, R., "Uber die Ausstromung- 
serscheinungen permanenter Gase," 
Ann. d. Physik, 69: 264, 1899. 

90. von Karman, Theodore, "Supersonic 
aerodynamics principles and appli- 
cations," J. Aeronaut. Sci., 14: 373, 
1947. 

91. Keenan, P. C., "Shadowgraph 
method of determining the strength 
of a shock wave," Phys. Rev., 69: 677 
1946. 

92. Keenan, P. C. and Polachek, H., 
"Measurement of densities in Shock 
waves by the shadowgraph method," 
NAVORD Rep. 86-46. 

93. Killing, V., "New techniques in 
photograms," Am. Phot., 46: 13, 
1952. 

94. Lafay, A., "Sur 1'utilisation du pro- 
cede d'exploration a 1'acetylene pour 
la mesure de la vitesse du vent et 
1'etude du champ aerodynamique," 
Comptes Rendus, 152: 694, 1911. 

95. McMillen, J. H. and Harvey, E. N., 
"A spark shadowgraph study of body 
waves in water," J. Appl. Phys., 17: 
541, 1946. 

96. McMillen, J. H., Kramer, R. L. and 
Allmand, D. E., "Shadowgrams of 
spherical missiles entering water at 
supersonic speeds," J. Appl. Phys., 21: 
1341, 1950. 

97. Marlow, D. G. and Nisewanger, 
C. R., "Development of the spark 
shadowgraphs," Air Tech. Intelligence, 
39131. 

98. Scheyer, B., "Special effects with 
photograms," Am. Phot., 43: 506, 
1949. 

99. Schmidt, E., "Warme und Kalte- 
technische Forschungen," Z. V.D.I., 
74: 1487, 1930. 

100. Stevens, V. I., "Hypersonic research 
facilities at Ames Aeronaut. Labora- 
tory," J. Appl. Phys., 21: 1150, 1950. 

101. Tanakadate, A., "Photographic study 
of air current produced by the move- 
ment of a screw propeller," Comptes 
Rendus, 151: 211, 1910. 

102. Taylor, G. I. and Maccoll, J. W., 



506 



October 1953 Journal of the SMPTE Vol. 61 



"The air pressure on a cone moving at 
high speeds," Proc. Roy. Soc., AT 39: 
298, 1933. 

103. Townend, H. G., "Hot wire and spark 
shadowgraphs of the airflow through 
an air stream," Phil. Mag., 74: 700, 
1932. 

104. Wachsmuth, R., "Labialpfeifen und 
Lamellentone," Ann. d. Physik, 14: 
469, 1904. 

Interferometric Application 

105. Bennett, F. D., Carter, W. C. and 
Bergdolt, V. E., "Interferometric 
analysis of airflow about projectiles in 
free flight," J. Appl. Phys., 23: 453, 
1952. 

106. Berl, E., "Die Anwendung der Inter- 
ferometrie in Wissenschaft und Tech- 
nik," Fortschritte der Chemie, Physik und 
Phys. Chemie., W: 7, 1928. 

107. Bershader, D., "An interferometric 
study of supersonic channel flow," Rev. 
Sci. Instr., 20: 260, 1949. 

108. Blue, R. E., "Interferometer correc- 
tions and measurements of laminar 
boundary layer in supersonic stream," 
NACA 7W2110, 1950. 

109. Eckert, E. R. and Soehngen, E. E., 
"Studies on heat transfer in laminar 
free convection with the Zehnder- 
Mach interferometer," USAAF TR, 
No. 5747, Dec. 1948. 

110. Gooderum, P. B., Wood, G. P. and 
Brevoort, M. J., "Investigation with 
an interferometer of the turbulent 
mixing of a free supersonic jet," 
NACA TN 1857, Apr. 1949. 

111. Groth, E., "Evaluation of density 
fields around airfoils in wind tunnels 
by means of optical interference," 
AVA Gottingen, Film 211, May 1946. 

112. Groth, E., "Evaluation of interferom- 
eter measurements on aerofoil in the 
250 x 250 mm. high-speed tunnel," 
Air Tech. Intelligence, 33: 769. 

113. Groth, E., "The evaluation of density 
field at high subsonic velocities by 
means of optical interference 
methods," Air Tech. Intelligence, 9888 
Dec. 1943. 

114. Groth, E., "Evaluation of density 
fields at high subsonic velocities by 
means of optical interference measure- 
ments," N.A.A. Report N.A., 8783, 
Nov. 26, 1945. 



115. Groth, E., "Measurement of flow 
around the airfoil by means of a 
Mach-Zehnder interferometer," Joint 
Intelligence Objectives Agency, 
Washington, BIGS-94, ADG 1011, 
Aug. 21, 1946. 

116. Groth, E., "Sensitivity and accuracy 
of the interference method applied to 
pressure measurements in wind tun- 
nels," Air Tech. Intelligence, 36783, 
ADG 1042. 

117. Hansen, G., "Uber die Ausrichtung 
der Spiegel bei einem Interferometer 
nach Zehnder-Mach," Z. Instrumen- 
tenk, 60: 325, 1940. 

118. Holden, J., "Shape of reflected inter- 
ference fringes from interferometers 
coated with thin metal films," J. Opt. 
Soc. Am., 41: 504, 1951. 

119. Hottenroth, "Uber Einige Erfahrun- 
gen am Mach-Zehnderschen Inter- 
ferometer," Forschungs bericht Nr. 1924, 
LFA, Braunschweig, Dec. 31, 1943 
(Translated Air Doc. Div. T-2, Ame. 
Wright Field) Air Tech. Intelligence, 
26635. 

120. Hutton, S. P., "The use of interferom- 
eters in aerodynamics," TN No. 
Aero. 1808, Royal Aircraft Establish- 
ment Report. 

121. Kennard, R. B., Temperature Distri- 
bution and Heat Flux in Air by Interferom- 
etry; Temperature, Its Measurement 
and Control, Reinhold Publishing Cor- 
poration, New York, 1941. 

122. Ladenburg, R., "Interferometric an- 
alysis of supersonic jets," NAVORD 
Report 74-46. 

123. Ladenburg, R., Panofsky, Van Voor- 
his, C. C. and Winckler, J., "Study of 
shock waves by interferometry," 
NDRC Report No. A 332 OSRD No. 
5204. 

124. Ladenburg, R., Van Voorhis, C. C. 
and Winckler, J., "Interferometric 
study of supersonic phenomena," 
NAVORD Report 69-46; NAVORD 
Report 93-46; NAVORD Report 7-47. 

125. Laue, M., "Interference phenomena 
with plane parallel plates," Ann. 
d. Physik, 13: 163, 1903. 

126. Laurence, J. C., "Interference method 
for obtaining the potential flow 
past an arbitrary cascade of airfoils," 
NACA TN 1252, 1947. 

127. Liepmann, H. W. and Bryson, A. E., 



Barnes: Optical Techniques 



507 



Jr., ''Transonic flow past wedge sec- 
tions," J. Aeronaut. Sci. 17: 745, 1950. 

128. Mach, E., Ann. d. Physik., 759: 330, 
1876. 

129. Mach, E., "The interference of spheri- 
cal waves," Ann. d. Physik, 41: 140, 
1890. 

130. Mach, E. and Gruss, Wien. Ber., 78: 
467, 1879. 

131. Mach, E. et alia, Various Papers, 
Sitzungsber. d. Kais. Akad. d. Wissen- 
schaften in Wien, 95: 764, 1887; 98: 
41, 1303, 1889. 

132. Mach, E. and Weltrubsky, J., "Uber 
die Formen der Funkenwelle," Wien. 
Ber., 78: 551, 1878. 

133. Matta, K. and Richardson, E. G., 
"Hot wire ultrasonic interferometer 
and its application to vapors," J. 
Acoust. Soc. Am., 23: 58, 1951. 

134. Olsen, H. L., "An interferometric 
method of gas analysis," Univ. of Wis- 
consin, CM-514 NORD 9938, Nov. 
1948. 

135. Ostwatitoch, K., "The measurement 
of density in an airstream by means of 
the double-slit interferometer," Air 
Tech. Intelligence, 18 473. 

136. Pack, D. C., "Investigation of the 
flow past finite wedges of 20 degree 
and 40 degree apex angle at subsonic 
and supersonic speeds using a Mach- 
Zehnder interferometer," British R. & 
M., No. 2321, 1949. 

137. Saunders, J. B., "An apparatus for 
photographing interference phenom- 
ena," J. Research Nat. Bur. Standards, 
35: 157, 1945. 

1 38. Schulz, L. G., "Interferometric method 
for accurate thickness measurements 
of thin evaporated films," J. Opt. Soc. 
Am., 40: 690, 1950. 

139. Tolansky, S., Multiple-Beam Inter- 
ferometry of Surfaces and Films, Claren- 
don Press, Oxford, 1948. 

140. Tolansky, S., "New contributions to 
interferometry with applications to 
crystal studies," J. Sci. Instr., 22: 
161, 1945. 

141. Twyman, F., "Interferometers for the 
experimental study of optical systems 
from the point of view of the wave 
theory," Phil. Mag., 35: 49, 1918. 

142. West, G. D., "An interferometer for 
sound waves," J. Sci. Instr., 6: 254, 
1929. 



143. Williams, W. E., Applications of Inter- 
ferometry, John Wiley and Sons, New 
York, 1950. 

144. Winckler, J., "The Mach Interferom- 
eter applied to studying an axially 
symmetric supersonic air jet," Rev. 
Sci. Instr., 79: 307, 1948. 

145. Work, R. N., "A photoelectric record- 
ing interferometer for measurement of 
dimensional changes," J. Research 
Nat. Bur. Standards, 47: 80, 1951. 

146. Zobel, T. W., "Flow Measurements 
by Light Interference," Air Tech. 
Intelligence, 26 165. 

147. Von Vietinghoff-Scheel, K., "Labo- 
ratory report on the investigation of 
flow around two turbine blade pro- 
files using the interferometer method," 
NACA TM, 1171, 1947. 

Interferometric Equipment 

148. Ashkenas, Harry I. and Bryson, 
Arthur E., "Design and performance 
of a simple interferometer for wind 
tunnel measurements," J. Aeronaut. 
Sci., 78: 82, 1951. 

149. Bergdolt, V. E., "A new interferom- 
eter with a large working field," 
Ballistics Res. Lab. Rep. 692, 1949; 
also Air Tech. Intelligence, 61 168. 

150. Gandler, C., Modern Interferometers, 
Hilger & Watts Ltd., London, 1951, 
available from Jarrell-Ash Co., 
Boston. 

151. DeFrate, L. A., Barry, F. W. and 
Bailey, D. Z., "A portable Mach- 
Zehnder interferometer," Project Me- 
teor Report No. 51, Feb., 1950. 

152. Eckert, E. R., Drake, R. M., Jr. and 
Soehngen, E. E., "Manufacture of a 
Zehnder-Mach interferometer," US- 
AAF TR No. 5721, Aug., 1948. 

153. Hansen, G., "Uber ein Interferom- 
eter nach Zehnder-Mach," Z. Tech. 
Physik., 12: 436, 1931. 

154. Kahl, G. D. and Bennett, F. D., 
"Experimental verification of source 
size theory for the Mach-Zehnder 
interferometer," J. Applied Phys., 23: 
763, 1952. 

155. Keating, T. J., "The Zehnder-Mach 
Interferometer," Plane Facts, 20-21, 
Oct. 1948. 

156. Lamia, E., "Calibration of the Mach- 
Zehnder Interferometer," Air Tech. 
Intelligence, 38908. 



508 



October 1953 Journal of the SMPTE Vol. 61 



157. Mach, L., "Uber ein Interferenzre- 
fraktometer," Wicn. Ber., 707: 5, 
1892; 702: 1035, 1893. 

158. Mach, L., "Uber Einige Verbesse- 
rungen an Interferenzapparaten," 
Wien. Ber., 707: 851, 1898. 

159. Peck, E. R., "A New Principle in 
Interferometer Design," J. Opt. Soc. 
Am., 38: 66, 1948. 

160. Price, E. W., "Initial adjustment of 
the Mach-Zehnder interferometer," 
Rev. Sci. Instr., 23: 162, 1952. 

161. Simmons, L. F. and Salter, C., "Inter- 
ferometer for recording turbulent 
flow," Aeronaut. Res. Comm. Great Brit. 
Rep. 1454, 1932. 

162. Waran, H. P., "New form of inter- 
ferometer," Proc. Roy. Soc. A 700: 
419, 1922. 

163. Winckler, J., "A mechanical evalu- 
ation method for interferometer 
photographs," Air Tech. Intelligence, 
1964. 

164. Zehnder, "Ein Neuer Interferenzre- 
fraktor," Z. Instrumentenk, 77: 275, 
1891. 

165. Zobel, T. W., "The development and 
construction of an interferometer for 
optical measurements of density 
fields," NACA TN No. 1184, also in 
Air Tech. Intelligence 22550. 

166. Zobel, T. W., "Optical corrections for 
interference by a controllable defor- 
mation of the reflecting surfaces," Air 
Tech. Intelligence 31 053. 

Interferometric Theory 

167. Bennett, F. D., "Optimum source size 
for the Mach-Zehnder interferom- 
eter," J. Appl. Phys., 22: 184, 1951 

168. Bennett, F. D. and Kahl, G. D., Theory 
of Mach-Zehnder Interferometer (to be 
published). 

169. Clippinger, R. F., "Comparison be- 
tween the Jamin-Mach interferom- 
eter and the Williams interferometer 
as applied to the study of airflow 
around a supersonic projectile of revo- 
lution," Ballistics Research Lab. Report 
567, Aberdeen, Sept. 21, 1945. 

170. Kennard, R. B., "An optical method 
for measuring temperature distri- 
bution and convective heat transfer," 
J. Research Nat. Bur. Standards., 8: 
787, 1932. 

171. Kinder, W., "Theorie des Mach- 



Zehnder Interferometers und Be- 
schreibung eines Cerates mit Ein- 
spiegeleinstellung," Optik, 7: 413, 
1946. 

172. Lamia, E., "Concerning the light 
path in a Mach-Zehnder interferom- 
eter," Jahrbuch 7947 der Deutschen 
Luftfahrtforschung, 727, Royal Aircraft 
Establishment Translation No. 80. 

173. Peck, E. R., "Theory of the corner- 
cube interferometer," J. Opt. Soc. Am., 
38: 1015, 1948. 

174. Schardin, H., "Theorie und Anwen- 
dung des Mach-Zehnderschen Inter- 
ferenz-Refraktometers," J. Instrument- 
enk, 53: 396, 424, 1933. 

175. Weyl, F. J., "Numerical aspects o. 
quantitative interferometry," Phys 
Rev., 69: 677, 1946. 

176. Winckler, E. H., "Analytical studies 
of the Mach-Zehnder interferometer," 
N.O.L. Report, 1077, Dec. 1949. 

General 

177. Adams, G. K., "A repetitive spark 
source for shadow and schlieren 
photography," J. Sci. Instr., 28: 379 
1951. 

178. Barnes, N. F. and Bellinger, S. L., 
"Schlieren and shadowgraph equip- 
ment for air flow analysis," J. Opt. 
Soc. Am., 35: 497, 1945. 

179. Barry, F. W., Shapiro, A. H. and 
Neumann, E. P., "The interaction of 
shock waves with boundary layers on a 
flat surface," J. Aeronaut. Sci., 78: 229, 
1951. 

180. Beardsley, E. G., "The NACA photo- 
graphic apparatus for studying fuel 
sprays from oil engine injection valves 
and test results from several re- 
searchers," NACA Tech. Rep., 274, 
1927. 

181. Bleakney, W., Weimer, D. K. and 
Fletcher, C. H., "Shock tube; a fa- 
cility for investigation in fluid me- 
chanics research," Rev. Sci. Instr., 20: 
807, 1949. 

182. Brenholtz, G. E., "An investigation of 
methods of visual flow," Air Tech. 
Intelligence, 89619, 1950. 

183. Brown, G. B., "On sensitive flames," 
Phil. Mag., 73: 161, 1932. 

184. Brown, G. Burniston, "On vortex 
motion in gaseous jets and the origin 



Barnes: Optical Techniques 



509 



of their sensitivity to sound," Proc. 
Phys. Soc., 47: 703, 1935. 

185. Buchele, D. R. and Day, P. B., "In- 
terferometer with large working field 
utilizing schlieren optics," NACA 
RM, E50 127, 1951. 

1 86. Dernback, A. F., "Interference method 
of studying airflow as used at the 
LFA Research Center," May 1945. 

1 87. Edgerton, H. E., "Double-flash micro- 
second silhouette photography," to be 
published in Rev. Set. Instr. 

188. Egerton and Gates, "On detonation 
of gaseous mixtures of acetylene and 
of pentane," Proc. Roy. Soc., Al '74: 
137, 152, 1927. 

189. Fage, A., "On the static pressure in 
fully developed turbulent flow," Proc. 
Roy. Soc., 155: 576, 1936. 

190. Fage, A. and Townend, H. C., ''An 
examination of turbulent flow with an 
ultramicroscope," Proc. Roy. Soc., 
AT 35: 656, 1932. 

191. Fayolle, P. and Naslin, P., "Photog- 
raphic instantanee et cinemato- 
graphic ultra-rapide," Editions de la 
Revue d'Optique, Paris, 1950. 

192. Ferri, Antonio, Elements of Aero- 
dynamics of Supersonic Flows, Mac- 
millan, New York, 1949. 

193. Foucault, Annales de rObservatoire 
Imp. de Paris, 5: 197, 1859. 

194. Garby, L. G. and Nelson, W. C., 
"University of Michigan 8x13 inch 
intermittent-flow supersonic wind tun- 
nel and appendix," Air Tech. In- 
telligence, 80958, June 1950. 

195. Gawthrop, D. B., Shepherd, W. G. 
and St. Perrolt, G., "The photography 
of waves and vortices produced by the 
discharge of an explosive," J. Franklin 
Inst., 211: 67, 1931. 

196. Jacobs, E. N., "Methods employed in 
America for experimental investi- 
gation of aerodynamic phenomena at 
high speeds," NACA Misc. Paper #42, 
Mar. 1936. 

197. Jones, E., "Photographic study of 
detonation in solid explosives," Proc. 
Roy. Soc., 720: 603, 1928. 

198. Kantrowitz, A. and Donaldson, G., 
"Preliminary investigation of super- 
sonic diffusers," NACA ACR L5D20, 
1945. 

199. Ladenburg, R., Winckler, J. and 
Van Voorhis, C. G., "Interferometric 



studies of faster than sound phenom- 
ena," Phys. Rev., 73: 1359, 1948 and 
Phys. Rev., 76: 662, 1949. 

200. Liepmann, H. W. and Puckett, A. E., 
Introduction to Aerodynamics of Com- 
pressible Fluids, John Wiley and Sons, 
New York, 1947. 

201. MacGoll, J., "The conical shock wave 
formed by a cone moving at high 
speeds," Proc. Roy. Soc., 159: 459, 
1937. 

202. Moore, A. D., "Further development 
of fluid mappers," Elec. Eng., 70: 396, 
1951. 

203. National Physical Laboratory Annual 
Report for 7932. 

204. "Kinematography of air flow," Na- 
tional Physical Laboratory Annual Report 
for 7933. 

205. Nelson, R. A., "Free convection of 
heat in liquids," Phys. Rev., 23: 94, 
1924. 

206. Nicholson, H. M. and Field, J. P., 
"Some experimental techniques for 
the investigation of the mechanism of 
flame stabilization in the wakes of 
bluff bodies," NOrd, 7386, Johns 
Hopkins University, Dec. 1948. 

207. Pugh, E. M., Heine-Geldern, R., 
Foner, S. and Mutschler, E. G., 
"Glass cracking caused by high 
photography," J. Appl. Phys., 23: 
48, 1952. 

208. Smith, L. G., "Photographic investi- 
gation of the reflection of plane shocks 
in air," Phys. Rev., 69: 678, 1946. 

209. Strong, J., Procedures in Experimental 
Physics, Prentice-Hall, New York, 
1938. 

210. Symposium on Wind Tunnel Optics, 
Air Tech. Intelligence, 82 325. 

211. Taylor, G. I. and MacGoll, J., "Air 
pressure on a cone moving at high 
speeds," Proc. Roy. Soc., 739: 278, 298, 
1933. 

212. Taylor, M. K., "A balsa-dust tech- 
nique for air-flow visualization and 
its application to flow through model 
helicopter rotors in stator thrust," 
NACA TN2220, 1950. 

213. Tietjens, O. , Wien, W. and Harms, J. 
Handbuch der Experimental Physik I: 
695, Leipzig, 1931. 

214. Tilton, L. W., "Optical glass of inter- 
ferometer and schlieren quality for 
wind tunnel optics," J. Research Nat. 
Bur. Standards, 42: 279, 1949. 



510 



October 1953 Journal of the SMPTE Vol. 61 



215. Tremblot, R., "Sur 1'ctude des cour- R.P.I.," Air Tech. Intelligence, 66990, 
ants gazeaux au moyen des inter- June 1949. 

ferences," Comptes Rendus, 792: 480, 218. Weyl, F. J., "Analytical methods in 

1931. the optical examination of supersonic 

216. Tremblot, R., "Sur 1'application des flow," NAVORD Rep. 211-45, Dec. 
interferences a quelques problemes 1945. 

d'ecoulement a grandes vitesses," 219. Williams, T. W. and Benson, J. M., 

Comptes Rendus, 193: 418, 1931. "Preliminary investigation of the use 

217. Von der Heyden, E., Jr., "The design of afterglow for visualizing low-den- 
of schlieren and shadowgraph appa- sity compressible flows," NACA TN 
ratus for the proposed wind tunnel at 1900, 1949. 



Barnes: Optical Techniques 511 



Conversion of 16mm Single-Head Continuous 
Printers for Simultaneous Printing of Picture 
and Sound on Single-System Negative 



By VICTOR E. PATTERSON 



The big rush for television news release prints from single-system negative 
prompted the design of this conversion unit. In news work every possible 
shortcut must be taken, without lowering the quality of the release prints. 
These converted printers cut the printing time in half; also, they save con- 
siderable raw stock, because in loop printing a splice may give way and create 
a synchronization problem in resplicing the negative, with the result that 
stock with sound printed but no picture usually has to be discarded. No loss 
occurs when picture and sound are printed simultaneously on these printers. 



I 



N NOVEMBER of 1951, McGeary-Smith 
Laboratories of Washington, D.C., re- 
quested a unit to attach to one of their 
Bell & Howell Model J printers to print 
single-system sound and picture at one 
time in order to speed up the printing of 
television news film. The unit described 
in this article was made and attached to 
one printer. It worked so efficiently 
and saved so much valuable time that a 
second printer was promptly converted. 

These units make it possible for prints 
to be taken off the processing machines in 
30 to 40 min after negative is received 
for timing and printing. Also, by using 
negative on a loop tree for continuous 
printing, one printer running at 90 fpm 
can keep a processing machine going 
at 80 fpm. This conversion may prove 

A contribution submitted August 5, 1953, 
by Victor E. Patterson, Telex Films, 5805 
44th Ave., Hyattsville, Md. 



of interest and value to laboratories 
doing television news work. 

Although it does not save time on 
double-system sound, the printer re- 
mains available for this work simply by 
turning off the lamp not needed at the 
time. In case of printer trouble this 
unit may be quickly removed and in- 
stalled on another printer, as no drilling 
or tapping is done on the printer casting ; 
instead existing screw holes are used. 
As a result of the design of the attachment 
the printer may be restored to its original 
design by merely removing the attach- 
ment and replacing the single-head 
printer parts. 

Figure 1 shows the parts needed for 
this conversion, consisting essentially of a 
prism made of plexiglas or optical glass 
(the one used here is optical glass). 
The prism has a tongue cut on its face 
which extends into the printing aperture 



512 



October 1953 Journal of the SMPTE Vol.61 




Fig. 1. Parts used in conversion. 







Fig. 2. Model J printer with unit attached to aperture housing. Elec- 
trical circuit box is fastened to printer fuse box. 

Patterson: Conversion of 16mm Printers 



513 




Fig. 3. Printer aperture with picture and sound lamps on. 
at bottom of lamp house is for cooling. 



Air hose 



as the original slide did on the printer. 
With this design there is no need for a 
partition between the picture and sound 
which might cause shading of the track 
area. 

A 50-w T-8 single-contact 120-v base 
lamp is used. The bracket for the lamp 
assembly is made from 14-gauge stainless 
steel formed to fit the printer housing 
and fastened on with two ^-in. 20 
screws. Formica is attached to this to 
hold the lamp base with an adjustment 
for moving the lamp up and down and 
around to center the filament. Also, a 
short length of stainless ^-in. tubing is 
inserted in the base for a compressed-air 
hose for cooling. The lamp cover is a 
piece of tubing with a light-tight cap. 
One screw locks the cover to the lamp 
base to prevent accidental removal while 
printing. The little prism cover locks 
the prism in the aperture after it has been 



adjusted. The six 2-56 screws that held 
the slide in place are used to fasten cover 
and prism to the printer. 

Figure 2 shows the unit installed on a 
printer. On the opposite side, attached 
to the fuse box, is a 7 X 9 in. radio 
chassis which holds a 0-1 50-v d-c meter, 
a 50-w 100-ohm variable resistor and a 
single-pole, single throw switch with a 
neon jewel light for Off and On of sound 
track lamp. The circuit is connected to 
the picture-lamp d-c power supply. 

Figure 3 shows the printer aperture 
with a piece of raw stock in place with 
the picture and sound lamps on. At the 
bottom of picture air hose and lamp 
wires go to rear of printer. After print- 
ing tests were made, it was found that 86 
v were correct for normal track exposure, 
which gives a long life to the lamp. 

To install this unit, first remove the 
housing cover plates as for normal main- 



514 



October 1953 Journal of the SMPTE Vol. 61 



tenance and cleaning. Then the aper- 
ture slide adjustment knob and ec- 
centric cam arc removed; also the slide 
and cover. These parts are left off the 
printer. After removing these parts 
there is exposed a -in. hole where the 
adjustment knob was located. This is 
used for the light path from lamp to 
prism. 

Next, two -J--20 screws are removed 
along side of the printer gate. These 
are replaced with two round-head -j-20 
screws ^ in. long to bolt the sound- 
lamp assembly to the housing. While 
doing this the filament is lined up with 
the center of the original hole that the 
adjustment knob was formerly in. The 
prism is placed in the aperture with its 
cover, which is left loose until the prism 
is adjusted for field and track placement. 
After the lamp is wired and the circuit 
connected to the power supply the final 
adjustment of the prism is made with 



picture and sound lamps on and a com- 
posite negative in the gate. Then the 
prism cover screws are tightened se- 
curely. In making this adjustment the 
lamp bracket may be moved slightly, 
as well as the lamp, to get the maxi- 
mum light output. The housing cover 
plates are put back on and the printer 
is ready for an exposure test. 

The prism is quite simple to adjust 
for track placement, and the field is good 
due to diffusion through the long prism. 
No condenser or reflector is needed, as 
the lamps burn far below their rated 
voltage (86 v for normal track on fine- 
grain release positive). 

The electrical circuits for these units 
were made and wired to the printers by 
Arthur Rescher of McGeary-Smith 
Laboratories, where for more than two 
years they have been used with a great 
reduction of printing time and main- 
tenance problems. 



Patterson: Conversion of 16mm Printers 



515 



An Improved Carbon-Arc Light Source for 
Three-Dimensional and Wide-Screen Projection 



By EDGAR GRETENER 



Three-dimensional and wide-screen projection both require substantially 
more than the conventional amount of screen light. The super Ventarc 
has been designed to meet these requirements to such an extent that the 
screen lumens are only limited by the maximum density of radiant energy 
the film can take. If this value is set at 0.7 w/sq mm, the ultimate limit for 
a 35mm projection system will be approximately 50,000 1m, with no film shutter. 
This level of screen light has been attained at 150 amp. 



Continuous Burning 

The recommended operation time for 
three-dimensional projection is 60 min 
continuous burning of the arc. Mirror 
arcs of normal design can take positive 
carbons up to only 20 in. in length. The 
positive support or carbon-guiding 
mechanism requires a carbon stub of 
about 2 in., and so reduces the useful 
carbon length to 18 in. As the consump- 
tion rate shows some variations, a safety 
margin of 10% should be provided. 
This means a further reduction of the 
useful carbon length to about 16 in. 
Limited by this consumption rate, the 
most screen lumens a present-day re- 
flector-type arc can produce with 80% 
screen distribution is 20,000, with an 
arc current of 115 amp and no film 
shutter. 

Up to the maximum limit for smooth 



Presented on October 9, 1953, at the So- 
ciety's Convention at New York by Hans 
Frey, Dr. Edgar Gretener, A. G., Otten- 
weg 25, Zurich, Switzerland, for Edgar 
Gretener. 
(This paper was received July 2, 1953.) 



operation, the screen light a high-inten- 
sity arc can produce increases with the 
increasing consumption rate of the posi- 
tive carbon, since the vapors produced 
by the evaporation of the carbon core 
constitute the light source. It thus be- 
comes necessary for maximum light that 
any limitation on carbon consumption 
rate be removed. Such limitations can 
be overcome by an arc which is capable 
of continuous burning. In order to do 
this it becomes necessary to attach a new 
carbon to the burning one as soon as the 
latter is consumed to a minimum length 
determined by the carbon support. 
This problem of joining positives proved 
to be a very difficult one for a cinema 
arc, since no failure of the joining proc- 
ess can be tolerated with a continuous 
show. Furthermore, the quality of the 
joint has to be such that no flicker or 
color change of the projection light 
appears on the screen when the joint 
burns through the arc. 

The process of joining positive carbons 
has been worked out by our firm in the 
past two years, with the kind assistance 
of the National Carbon Company. The 



516 



October 1953 Journal of the SMPTE Vol. 61 



Core 



Shell 



Protrusion 

Fig. la. Positive carbons. 

Positive feed 



Joint 



Arc 
Figure Ib 



Ring negative 



results are now so satisfactory that this 
method is ready for practical use. 

The nonrotating positive carbon of 
the Super Ventarc Lamp makes the 
joining problem much easier. From a 
practical point of view, the dimensional 
tolerances normally associated with large- 
scale production processes must be taken 
into consideration, so that a joining 
method requiring a very high precision 
of the parts to be joined would be of 
little practical interest. The positive 
carbons for continuous operation are 
designed as shown in Fig. la, so that the 
core protrudes at one end, with a com- 
plementary hole formed at the other. 
A magazine holding positive carbons is 
provided in the lamphouse. As soon 
as the length of the burning carbon 
reaches a certain value, a contact is 
operated which causes a new carbon to 
leave the magazine and be joined to the 
burning carbon, the hollow end of the 
new carbon sliding over the protruding 
core on the cold end of the burning one 
(Fig. Ib). The parts to be joined are 
impregnated by the manufacturer with 
a special cement. As the joint moves 
toward the positive head, it is heated by 
a simple electrical oven, which hardens 
the cement. The magazine can be de- 
signed to take any quantity of positive 
carbons, and it can be refilled while the 
arc is burning. 

With the continuous feed for the posi- 
tive carbons, an adequate system must 



also be provided for the negative elec- 
trode. To obtain maximum brilliance 
from the arc, the current density in front 
of the positive crater must be increased 
to the maximum extent possible, thus 
causing a high evaporation rate of the 
positive carbon. With a rod negative 
and an arc length of reasonable value, 
this would give rise to "mushroom" 
deposits on the tip of the negative, 
resulting in erratic burning. These dif- 
ficulties are overcome by the use of a disk 
negative, mounted in a meridional plane 
of the illumination system. During 
operation of the arc, this negative disk 
is slowly rotated. All evaporation 
products condensing at the edge of the 
disk are thus transported outside the 
arc stream and oxidized in the open 
air. The disk consumes slowly at a 
rate dependent upon the arc current 
and other factors, and has a useful life 
of the order of five to ten hours burning 
time. The blown arc equipped with 
the continuous feed mechanism for the 
positives and combined with a suitably 
designed disk negative thus constitutes 
a source which can meet any require- 
ment for cinema projection, within the 
limits imposed by the sensitivity of the 
film to the heat generated. 

The Light Source 

If the rate of evaporation of the core 
is high enough, the concentrated arc 
stream in front of the positive crater 



Gretener: Carbon-Arc Light Source 



517 



Auxiliary mirror 



Film aperture 




Main 
Reflector 



Fig. 2. Illumination system. 



shows the same brightness as the crater 
itself. The absorption in the arc rises 
with increasing evaporation of the 
positive core until the crater edge is no 
longer visible through the arc. Under 
these conditions the arc stream replaces 
the positive crater as the light source. 
The brilliancy of this arc stream decreases 
with increasing distance from the crater. 
To get a cylindrical source of constant 
brilliancy along its axis, an auxiliary 
mirror is provided near the arc, as 
shown in Fig. 2. This auxiliary mirror 
picks up the back radiation of the arc 
stream and forms an inverse image of 
the arc in itself. Seen from the direction 
of the main mirror the arc stream seems 
to operate between two positive carbons 
(Fig. 2). 

This light cylinder produces many 



more lumens than the crater itself, and 
in addition it offers much better condi- 
tions for the illumination system. Re- 
ferring to Fig. 3a, a flat source produces 
a very sharp peak in the center of the 
film aperture if the collecting angle a 
of the mirror is increased to 90 in order 
to collect all the radiation of the flat 
source. This is due to the fact that 
the mirror-surface elements near the 
edge of the mirror see the source as a 
very narrow ellipse, with the small axis 
degenerating to zero for a 90 viewing 
angle. Because of this bad effect, the 
collecting angle of the mirror is normally 
limited to 70-75. 

In contrast with this, the cylindrical 
light source offers its very best qualities 
from a viewing angle of 90 to the carbon 
axis. This is illustrated in Fig. 3b. 



518 



October 1953 Journal of the SMPTE Vol. 61 




Light 
distribution 



Fig. 3a. Elliptical reflector in focus /i/ 2 flat source. 




Light 
distribution 



Fig. 3b. Elliptical reflector in focus /i/ 2 cylindrical source 
with auxiliary mirror. 



The illumination system of the Super 
Ventarc has therefore been designed to 
embrace the total solid angle around 
the source, the auxiliary mirror and the 
main mirror having each a collecting 
angle of about 90. 

The combination of the two mirrors 
not only picks up the total radiation 
from the cylindrical source, thus giving 



maximum efficiency for the illumination 
of the film aperture, but also prevents 
the lamp house from being heated by 
waste light from the arc. 

Maximum Screen Illumination 

The maximum possible light flux for 
a projection system is limited by the 
tolerable density of radiant energy in 



Gretener: Carbon-Arc Light Source 



519 






the film aperture. This limit is not 
precisely established, but it is known to 
be in the neighborhood of 0.7 w/sq mm 
(measured with no film shutter) for 
normal projectors without forced-air 
cooling. This unit value holds for 
every part of the film area, so that a 
hot spot in the center of the aperture 
limits the total screen lumens long before 
the tolerable density of radiant energy 
is reached for the sides and corners of 
the picture. For this reason, uniform 
screen illumination is desirable. In any 
event, bad light distribution is par- 
ticularly to be avoided in the projection 
of three-dimensional and wide-screen 
pictures. 

For highest screen lumens, the highest 
possible ratio of lumens per watt has 
to be provided at the aperture. With- 
out heat filters, a high-intensity arc 
gives about 115 aperture Im/aperture 
w, with no shutter. Cutting all invisible 
radiation, this goes up to 230 Im/w. 
Further cutting of the red and blue end 
of the visible spectrum raises this ratio 
to 300 Im/w, if the white is permitted 
to shift one threshold toward green. 
This is not noticeable with a projection 
system if this greenish white cannot be 
compared directly with a correct white; 
and a light loss of no more than 1.75% 
is involved if all radiation beyond the 
range between 430 and 650 m/j, is 
eliminated. 

The ideal radiation filter transmitting 
430 to 650 m/j, will be of the interference 
type, but this is not yet commercially 
available; any practical filter will 
produce some light losses and transmit 
some invisible radiation. Further, the 
transmission factor T of a good surface- 
treated lens can be set to 0.90. Recog- 
nizing these factors, it is always useful 
to set up the final target. The ultimate 
screen lumen figure thus becomes: 

L = A-d'-n-T 

where A is the area of the aperture in 
sq mm, 



5 is the maximum tolerable 
radiant energy at the aperture 
in w/sq mm, 
rj is the luminous efficiency of this 

energy in Im/w, 
and T is the lens transmission. 
Substituting the values : 
A = 320 sq mm for 35 mm film, 
<5 =0.7 w/sq mm, 
i) = 300 Im/w, and 
T = 0.9, we get 

L = 320 X 0.7 X 300 X 0.9 = 
60,000 1m without the film 
shutter. 

This value holds for an even light 
distribution over the screen. With an 
80% side-to-center distribution, it is 
reduced to 50,000 1m. 

Any light losses of the heat filter can 
be compensated by a slight increase of 
the arc current, and any transmission 
of invisible radiation can be suppressed 
by additional filter layers. Conse- 
quently the 50,000 1m will be available 
in the future if the cutoff at both ends 
of the visible spectrum can be made 
sharp enough and if projection-lens 
efficiency is 90%. This ultimate screen- 
lumen figure will grow proportionally if 
the heat tolerance of the film can be 
increased by forced-air cooling or the 
use of improved film material. 

It must be pointed out that infrared 
transmitting mirrors are not suitable 
for very high-current arcs, as the support 
glass will be spoiled in a short time by 
deposits from the arc. The Super 
Ventarc uses a metallic mirror evapo- 
rated with aluminum and with a pro- 
tective layer of silicon monoxide. This 
protecting layer is so thin that its heat 
resistance is quite negligible. If hot 
particles fall on the surface of this 
mirror, the high heat conductivity of the 
metal prevents local melting, so that 
the particles do not fuse with the mirror 
surface but fall harmlessly to the bottom 
of the lamphouse. Comparative tests 
with a very heavily loaded positive 
crater showed the striking superiority 



520 



October 1953 Journal of the SMPTE Vol. 61 



Spring 
pressure 



Flexible air pipe 




Fig. 4. Positive head. Auxiliary 
mirror 

of the metallic mirror with regard to 
these sputtering effects. 

Color Projection 

Three-dimensional and wide-screen 
projection must be combined with color. 
Since the picture is so much more 
realistic, the very best color has to be 
provided, and any color errors are much 
more noticeable than with a normal two- 
dimensional picture. 

With subtractive color, the color 
quality is directly related to the trans- 
parency of the film, in such a way that 
really good color is only available with 
prints of high density. This is true as 
long as such dyestuffs as change satura- 
tion and hue with varying density are 
used for subtractive color. 

Since color for three-dimensional and 
wide-screen projection has to be of the 
highest quality, it would not be practical 
to try to obtain more screen light for 
these processes by making color prints 
of higher transparency than that usual 
today for normal two-dimensional 
pictures. 

Progress in Design Since 1950 

In an earlier article 1 the author 
described a Ventarc giving a maximum 

1 Edgar Gretener, "Physical principles, 
design and performance of the Ventarc 
high-intensity projection lamps," Jour. 
SMPTE, 55: 391-413, Oct. 1950. 



Flexible 
water pipe 



output of 30,000 screen 1m with 100 
amp. The Super Ventarc presently 
described shows substantial progress in 
comparison with the technique used in 
1950. The main improvements may 
be summarized as follows: 

1. The Super Ventarc is provided 
with a magazine feed for the positives 
for continuous burning of the arc. 
Relatively short carbons can be used 
with this operation, thus giving better 
basic conditions for the optical illumi- 
nation system. The 45 deflection mirror 
used with a vertical carbon in the earlier 
lamp can thus be avoided, and the 
positive is now arranged in the con- 
ventional horizontal position. 

2. The design of the positive head 
has been improved by separating the 
carbon guide from the contact pieces, 
so that the centering of the positive is 
no longer affected by any wear of the 
contact pieces. These contacts are 
shaped as half cylinders, are directly 
water cooled, and each incorporates an 
air nozzle. Water, arc current, and 
compressed air are fed to the two con- 
tacts through flexible connections from 
a central distributor block. The carbon 
guide pieces are assembled with this 
block to form a stable unit. The contact 
pieces are pressed against the positive by 
a spring system which allows the contacts 
to adhere perfectly to the surface of the 
positive, without influencing the correct 
centering of the carbon (Fig. 4). 



Gretener: Carbon-Arc Light Source 



521 



Ring negative 




Suction 
pipe 



Ring support 



Positive 




'Suction pipe 
Fig. 5. Negative electrode. 



3. The big negative ring used in 
1950 which surrounded the positive 
head is now replaced by a much smaller 
one, located entirely at the negative 
side of the arc, and penetrating the 
elliptical reflector through a suitably 
shaped slot. With the metallic re- 
flector used, this proved to be possible 
without sacrifice of the optical precision. 

Figure 5 shows the negative-electrode 
arrangement, in which a suction pipe 
picks up the hot arc gases at the inner 
side of the ring negative. This arrange- 
ment permits a very simple design of the 
negative support and its driving 
mechanism. 

4. As the main reflector, together 
with the auxiliary mirror, embraces the 
total solid angle round the arc stream, 
the front part of the positive head and 
the main reflector are not directly 
accessible for inspection and cleaning. 
For this reason, the whole negative 
part of the lamp mechanism, including 
the main reflector, the suction pipe 



and the negative drive is arranged to 
swing out around a vertical axis, thus 
giving the very best accessibility to 
all the important parts requiring service 
attention. The suction pipe is de- 
signed to go through this axis of rotation, 
so it need not be disconnected. 

5. The blower producing compressed 
air for the positive head and suction for 
the negative pipe is arranged at the 
top of the lamphouse. It is driven 
very smoothly and silently by an in- 
duction motor. The lamphouse is 
ventilated by an ejector system driven 
by the exhaust of the suction pipe. 
This design proved to be more effective 
and less costly than the ejector system 
used in 1950. Furthermore, it avoids 
the necessity of providing additional 
blowers outside the lamphouse. 

6. The heat filter has been arranged 
in a slide near the dowser, so that it can 
easily be taken out for inspection and 
cleaning, 

The main reflector of the Super 



522 



October 1953 Journal of the SMPTE Vol. 61 



50K?Lm. 



40 



1953 



30 



20 



10 



I948 



7 



1950 



/ 



7 



6 50 100 150 200 AMR 

Fig. 6. Screen lumens, side-to-center ratio 80%: I, Ventarc 
lamps; II, conventional reflector-type arcs (NCC). 




200 AMR 



Fig. 7. Lumens per arc watt: I, Ventarc lamps; 
II, conventional reflector-type arcs (NCC). 



Ventarc has been enlarged to a diameter 
of 24 in. This gives the necessary space 
for the positive head with the auxiliary 
mirror, the ring negative and the 
magazine feed for the positives, without 
causing any substantial light losses due 
to shadow masking of the illumination 
beams. 

The big lamphouse associated with 
the 24-in. mirror gives the necessary 
safety margin for operating the arc, 
even with extremely high load. 



The Screen Light From the 
Super Ventarc 

Figure 6 gives the screen lumens of 
the Ventarc Lamp in which the range 
between 100 and 200 amp is covered 
by the Super Ventarc (SVA). It will be 
noted that a screen lumen level of ap- 
proximately 50,000 lumens without shut- 
ter has been attained at 1 50 amp. Screen 
lumens per arc watt (Im/arc w) are 
plotted in Fig. 7. This value represents 



Gretener: Carbon-Arc Light Source 



523 



08-- 



06 



04 



02 - 



/\ 



Center 



Corner 



8 



10 



12 



14 Win. 



Fig. 8. Super Ventarc, 150 amp, screen light variations with time; 
b, relative brightness. 



a figure of merit for the efficiency of the 
arc lamp. The distinction between 
arc watts as involved here, and the 
aperture watts used in earlier lumen-per- 
watt calculations should be noted. For 
comparison, the corresponding figures 
for conventional reflector-type arc lamps 
are plotted in the same diagrams. These 
figures have been taken from the paper 
by Holloway, Bushong and Lozier, 2 
giving a survey on screen illumination 
with carbon arc 35mm motion-picture 
film projection systems. It should be 
noted that the most powerful arc of 
conventional type described there, run 
with 195 amp and giving 28,000 screen 



2 F. P. Holloway, R. M. Bushong and 
W. W. Lozier, "Recent developments in 
carbons for motion-picture projection," 
Jour. SMPTE, 67: 223-240, Aug. 1953. 



lumens with a side-to-center distribution 
of 80%, is only an experimental one. 
In contrast, the Super Ventarc figures 
stand for performance values which can 
be guaranteed for practical use. 

The screen light from the Super 
Ventarc is homogeneous over the screen 
with regard to its spectral composition. 
The red-to-green ratio of the light 
measured at center, sides and corners 
of the screen shows no variation exceed- 
ing the measuring precision. This 
homogeneity is of importance for the 
projection of high-quality color films. 

The screen light variations with time 
for center, sides and corners of the screen 
are shown in Fig. 8. It is seen from this 
diagram that the Super Ventarc meets 
the highest requirements which may be 
set up for three-dimensional and wide- 
screen projection regarding stability of 
screen illumination. 



(See page 532 for Convention discussion of this paper.} 



524 



October 1953 Journal of the SMPTE Vol.61 



Performance of High-Intensity 
Carbons in the Blown Arc 



By C. E. GREIDER 



The performance of carbons operated in the Gretener type of "blown arc" 
shows the following advantages as compared with the more usual method of 
burning: (a) from 5 to 25% less current is required to produce the same light; 
(b) at the higher brightness levels, less carbon consumption is required for the 
same light; (c) the maximum light that the carbon will deliver is increased by 
10 to 20%; and (d) uniformity of brightness across the face of the arc crater is 
considerably improved. The performance advantages of the "blown arc" 
seem to be considerably greater for 12-mm than for 10-mm carbons, and are 
greatest when the carbon is operated at or near its maximum current and light 
output. The addition of blowing to the arc introduces special problems re- 
garding the design and operation of the negative electrode. 



J. HE "blown arc" as described by 
Gretener 1 is strikingly different in ap- 
pearance from the more usual form of the 
high-intensity carbon arc. The object 
of the present work was to determine 
whether this change in the shape and 
appearance of the light source produces a 
change in its light output, and more 
specifically, its effect on the relationship 
between light output, arc current and 
rate of consumption of the positive car- 
bon. 

Presented on October 9, 1953, at the So- 
ciety's Convention at New York by G. E. 
Greider, Research Laboratories, National 
Carbon Co., a Division of Union Carbide 
and Carbon Corp., Cleveland, Ohio. 
(This paper was received August 31, 1953.) 



In the Gretener "blown arc," the posi- 
tive carbon is surrounded by a magnet 
coil to "homogenize" the arc, together 
with a ring of air jets which direct a 
conical stream of air inward toward the 
arc. The latter changes the character 
and direction of the arc flame so that, 
instead of curving upward as it leaves the 
arc crater, it is concentrated and pro- 
jected straight forward from the crater. 
The negative electrode is directly in front 
of the positive, in the path of this arc 
flame, which without the blowing would 
give an extremely unsteady arc at the 
high currents used. If a carbon rod of 
the customary shape is used for the nega- 
tive electrode, deposits of carbon or rare 
earth carbide tend to form on its tip, 



October 1953 Journal of the SMPTE Vol. 61 



525 




If 





Fig. 1. Arc lamp mechanism for the "blown arc," using 12- mm positive carbons 
and a graphite disk negative. 



causing unsteady operation. This can 
often be alleviated by small changes in 
the composition of the negative carbon 
or in its alignment. A preferred solu- 
tion may be the substitution of a slowly 
rotating graphite disk as the negative 
electrode, as described by Gretener. 1 
This does away with the formation of 
either mushroom carbon or rare earth 
carbide on the negative, but it is too 
early as yet to say whether it has elimi- 
nated all the problems associated with the 
negative electrode that are introduced 
by the addition of blowing to the arc. 

Figure 1 shows the "blown arc" 
mechanism installed in an experimental 
test lamp, using the graphite disk nega- 
tive. Figure 2 is a photograph of the 
"blown arc" in operation, using the same 
negative with a positive carbon of 12-mm 
diameter. The arc length is held at 



1 5 mm, and the protrusion of the positive 
carbon from its holder is also 15 mm. 

Since this work was designed to evalu- 
ate the effect of blowing, measurements 
with the same carbons were also made 
without blowing, keeping all other opera- 
ting conditions the same as in the "blown 
arc" so far as possible. The same ex- 
perimental test lamp was used, with 
silver water-cooled jaws previously de- 
scribed, 2 since water-cooled jaws are also 
used in the "blown arc" in order to 
obtain maximum performance from the 
high-brightness carbons used. The same 
positive protrusion of 15 mm was main- 
tained. The angle between the axis of 
the negative and positive carbons was 
53, which when the arc is operated 
without blowing, seems to give the best 
performance with the carbons and arc 
currents used. 



526 



October 1953 Journal of the SMPTE Vol. 61 



Fig. 2. The "blown arc," with 12-mm positive carbon 
and graphite disk negative. 



Methods of Light Measurement 

The light output with or without blow- 
ing was measured directly in terms of 
brightness at the crater of the arc, with- 
out consideration of any particular 
optical system. Direct crater-brightness 
measurements have the advantage of 
showing changes in brightness distri- 
bution across the crater face, which 
demonstrate more clearly the causes of 
observed differences in total light output. 
They can also be used to predict with 
reasonable accuracy the projection per- 
formance in any assumed optical system. 3 

All the measurements of arc-crater 
brightness were made at an angle of 50 
from the axis of the positive carbon. 
Both the brightness and the light output 
of the arc crater will vary with angle of 
view; the choice of 50 represents a 
reasonable midpoint, since a typical mir- 
ror system will collect about the same 
amount of light in the outer zone beyond 
50 as it will in the zone inside this angle. 

Where the "blown arc" is shown by 



these measurements to have an advan- 
tage over conventional operation, this 
advantage may be greater in terms of 
screen light than is shown in the com- 
parisons of crater brightness at 50 if 
a mirror with a large collecting angle is 
used. In the "blown arc," considerably 
more light is generated in the space 
directly in front of the crater. Measure- 
ments limited to crater brightness do not 
indicate the contribution which this cone 
of light in front of the crater can make to 
the total screen light, especially the light 
collected by the outer zones of the mirror, 
or by an auxiliary mirror. 

The brightness across the crater face 
was measured by the method described 
by Jones, Zavesky and Lozier 4 in which 
a photocell is driven across a projected 
image of the crater, in synchronism with 
a recording meter which is calibrated 
(with the photocell) to give a direct 
reading of intrinsic brightness. Curves 
of crater brightness versus position are 
thus obtained across the crater face both 



Greider: Carbons in the Blown Arc 



527 






horizontally and vertically through the 
center of the crater image. From these 
curves, the maximum and center bright- 
ness can be read directly, and the aver- 
age brightness can be readily calculated. 
To facilitate comparison, this average 
brightness is calculated only for a circular 
area of 10-mm diameter centered on the 
crater, when using 12-mm carbons or 
8-mm diameter with 10-mm carbons. 
Because of the greater spindle in the 
"blown arc," the actual diameter of the 
arc crater will be only a few tenths of a 
millimeter larger than that of the area 
used for measurement of brightness. 

This average brightness is independ- 
ently determined by a second method 
suggested by Gretener, in which the 
entire image of the crater is projected 
onto the face of a photocell, using a 
much lower magnification than in the 
preceding case. The photocell is masked 
so as to admit only the light from the 
central 8 or 10 mm of the crater. Since 
the crater is viewed from an angle of 50, 
this mask is elliptical rather than cir- 
cular. These two methods of measuring 
crater brightness give excellent agree- 
ment, the difference between them being 
no more than 2 or 3%. 

The Carbons 

The comparisons reported below were 
all carried out with experimental car- 
bons similar to the high-brightness type 
(Ultrex) carbons whose performance 
characteristics were recently described 
by Holloway, Bushong and Lozier. 5 A 
few comparisons made with carbons not 
designed to give so high a brightness 
have shown that blowing has about 
the same effect on performance as with 
these "high-brightness" carbons. Two 
different sizes of carbons were used, 
having diameters respectively of 10 and 
12 mm. The 10-mm carbon is the one 
used in the " Super- Ven tare" described 
by Gretener in this issue of the Journal, 
while the 12-mm carbon has been used 
experimentally in the projection of 



900 



700 



600 









NOT 
BLOWN 



140 170 200 230 

ARC CURRENT - AMPERES 



260 



Fig. 3. Reduction in current require- 
ment with "blown arc" operation. 12- 
mm high-brightness carbons. 

theater television by the Eidophor proc- 
ess. With each carbon size, the core 
size and composition were selected to 
give the best efficiency in terms of cur- 
rent requirement and carbon consump- 
tion, consistent with steadiness of opera- 
tion. 

Comparative Results 

The most outstanding and consistent 
effect of blowing is the lower current 
that is required to give the same light 
(or average crater brightness). This 
has been found true for all grades and 
sizes of carbons that have been ex- 
amined. The magnitude of the differ- 
ence is shown in Fig. 3 for the 12-mm 
high-brightness carbon. With this par- 
ticular carbon the decrease in current 
required is from 30 to 40 amp or from 
15 to 20%. 

One reason for the lower current re- 
quirement in the "blown arc" is the 
smaller diameter of the arc crater at 
either the same current or the same 
brightness. This is caused by the air 
jet, which increases the oxidation or 
spindle on the outside of the shell. The 
amount of this difference will depend on 



528 



October 1953 Journal of the SMPTE Vol. 61 



1000 



900 



800 



700 



600 



500 






BLOWN 



NOT 

BLOWN 



15 30 45 60 75 

CARBON CONSUMPTION -INCHES PER HOUR 

Fig. 4. Effect of "blown arc" operation 
on carbon consumption. 12-mm high- 
brightness carbons. 

operating conditions, but for 12-mm 
carbons the "blown arc" at the same 
brightness will have a crater from \ to 
1 mm smaller in diameter than obtained 
without blowing. A lower arc current 
will, therefore, be required with the 
"blown arc" to give the same current 
density at the crater, because of the 
smaller crater area over which the cur- 
rent is spread. 

This smaller crater diameter, however, 
is not enough in itself to account for all 
the decreased current requirement. The 
effect of this factor can be eliminated by 
decreasing the shell thickness of the 
carbon when operated without blowing 
in order to compensate for the extra 
carbon that is burned away in the "blown 
arc," keeping the carbons otherwise 
identical. 

Such a comparison shows that the 
smaller crater diameter of the "blown 
arc" is responsible for less than half of the 
decrease in current requirement. The 
rest may be due to the effect of the air 
jet in keeping the arc off the sides of 
the carbon, so that all the current is dis- 
charged in the crater itself. An alterna- 
tive explanation is that the redirection 



of the arc flame produced by the blowing 
permits more effective utilization of the 
light-giving material (rare earth vapors) 
in the production of usable light. 

The "blown arc" also requires lower 
carbon consumption for the same light 
output, especially at high levels of aver- 
age brightness. This comparison is 
shown in Fig. 4 for the same 12-mm car- 
bons of Fig. 3. The carbon consump- 
tion is about the same for either type of 
operation at an average crater brightness 
of 500, but as brightness is increased 
beyond this point, the "blown arc" 
shows increasingly greater superiority. 
It can also be run at a higher level of 
average brightness. This highest bright- 
ness obtained with this carbon without 
blowing (as normally operated) was no 
more than about 800 cp/sq mm, while 
in the "blown arc" it can readily be 
made to exceed 1000 cp/sq mm. 

The principal reason for the higher 
average crater brightness with the blown 
arc is a much more uniform brightness 
distribution across the crater face. The 
light intensity at the point of maximum 
brightness is little if any higher, but a 
larger proportion of the total crater 
area equals or approaches this maximum 
brightness. This is illustrated in the 
curves for brightness distribution across 
the crater face for the two types of opera- 
tion, shown in Fig. 5. At the point 
of maximum brightness near the center 
of the crater, both carbons show the 
same brightness of about 1400 cp/sq mm. 
Without blowing, however, the bright- 
ness falls off much more rapidly as the 
crater edge is approached. The "blown 
arc," therefore, can give much higher 
average crater brightness for the same 
center or maximum brightness. 

The curves of Fig. 5 show also that 
with our conditions of measurement, 
the greatest improvement in uniformity 
and increased light output from the 
"blown arc" appears in the brightness 
curve measured in a horizontal plane 
through the crater. This gives a clue 
to the reason for the improvement. 



Greider: Carbons in the Blown Arc 



529 



1500 



1200 



900 



600 



300 




363 

MILLIMETERS FROM CENTER OF CRATER 



Fig. 5. Brightness distribution across the crater face with "blown arc" and con- 
ventional operation. High-brightness carbons with same core and crater size. 



IIUU 












. 


1000 






BLOWN / 






y^LOWN 






/ 




/ 








/V^ 






/ X 






/ 


s 






/ / 


900 




/ = 


(VN 




/ 


/IOT 
ILOWN 




/ 








// 






/ 








/ 






| 








/ 




600 














5 30 45 60 125 150 17 



CARBON CONSUMPTION 
INCHES PER HOUR 



ARC CURRENT 
AMPERES 



Fig. 6. Effect of "blown arc" operation with 10-mm high-brightness carbons. 
530 October 1953 Journal of the SMPTE Vol. 61 



Table I. Performance of "Ultrex" Type Carbons in the Blown Arc. 



Current, 
amp 


Arc 
voltage 


Carbon 
consumption, 
in./hr 


Avg crater 
brightness 
cp/sq mm 


10-mm carbons 125 
140 
155 
170 

12-mm carbons 150 
175 
200 
210 


60 
63 

71 
78 

55 
64 

71 

75 


20 
28 
46 
64 

17 
28 
48 
56 


610 
780 
960 
1080 

505 

725 
875 
935 



Without blowing, the "tail flame" is 
directed upward and away from the arc, 
and most of its light is not used, as shown 
in the sketches of the arc image in Fig. 5. 
In the "blown arc" this flame is concen- 
trated and projected straight forward 
from the crater. Even if only crater 
brightness is measured, the brightness 
along the horizontal plane A-A is built 
up considerably by this addition from the 
arc flame, while if the optical system is so 
designed as to pick up light effectively 
from the area in front of the crater, the 
increase in usable light may be even 
greater. The increase in light appears 
principally in the horizontal brightness 
distribution curve because the 50 
angle of view was in a horizontal plane 
with respect to the carbon axis; if the 
angle of view had been in a vertical 
plane, the increased light would have 
been mostly in the vertical brightness 
distribution curve. 

The advantages of the "blown arc" 
seem to be somewhat greater with 12-mm 
carbons than with the 10-mm size. A 
typical comparison with 10-mm high- 
brightness (Ultrex) type carbons is 
shown in Fig. 6. It is seen from this 
that with the "blown arc", less current 
is required to produce the same bright- 
ness, but that the difference between 
the two is not as great as with the larger 
size. The 10-mm carbon as a "blown 
arc" does not show lower carbon con- 
sumption for the same brightness until 
the average crater brightness exceeds 



800 cp/sq mm. As with the 12-mm 
carbon, the advantage in carbon effici- 
ency increases as the brightness is in- 
creased, and the carbon is able to reach 
a higher average brightness in the "blown 
arc" than without blowing. 

The light output of the "blown arc" 
is affected to some extent by operating 
conditions such as the strength of the 
applied magnetic field, the air pressure 
in the stabilizing air jets, and the effec- 
tiveness of the water cooling at the posi- 
tive carbon jaws. Normally, however, 
variation of these factors which still 
permits satisfactory "blown arc" opera- 
tion will not affect light or carbon con- 
sumption by more than about 5%. 
Typical values for current, carbon 
consumption and light (average crater 
brightness) are given in Table I for the 
10- and 12-mm high-brightness type of 
carbons operated in the "blown arc." 

The results of this work lead to the 
conclusion that "blown arc" operation 
permits a carbon to deliver consider- 
ably more light and to deliver the same 
amount of light at both a lower current 
and a lower rate of carbon consumption. 
Its advantages seem to be greater with 
12-mm than with 10-mm carbons, 
while with a given carbon the superiority 
of blowing is greatest at the highest 
light output the carbon is capable of 
delivering. This type of operation 
should, therefore, find its greatest use- 
fulness in conditions requiring an ex- 
tremely high light output. 



Greider: Carbons in the Blown Arc 



531 



References 

1. Edgar Gretener, "Physical principles, 
design and performance of the ventarc 
high -in tensity projection lamps," Jour. 
SMPTE, 55: 391-413, Oct. 1950. 

2. M. T. Jones and F. T. Bowditch, 
"Optimum performance of high-bright- 
ness carbon arcs," Jour. SMPE, 52: 
395-406, Apr. 1949. 

3. M. T. Jones, "Motion picture screen 
light as a function of carbon-arc-crater 



brightness distribution," Jour. SMPE, 
49: 218-240, Sept. 1947. 

4. M. T. Jones, R. J. Zavesky and W. W. 
Lozier, "Method for measurement of 
brightness of carbon arcs," Jour. SMPE, 
45: 10-15, July 1945. 

5. F. P. Holloway, R. M. Bushong and 
W. W. Lozier, "Recent developments in 
carbons for motion-picture projection," 
Jour. SMPTE, 61: 223-240, Aug. 1953. 



Discussion on "An Improved Carbon- Arc Light Source for Three-Dimensional 
and Wide-Screen Projection," by Edgar Gretener 



[After the paper, E. I. Sponable of 
Twentieth Century-Fox announced that 
the model on display was the first factory 
model and that its operation would be 
demonstrated later at the Twentieth 
Century-Fox laboratory.] 

David B. Joy (National Carbon Co.): 
Referring to Fig. 6, a value of about 
50,000 lumens is indicated for the Ventarc 
lamp. This value is, as Mr. Frey pointed 
out, about twice as high as what is now 
available in many of our largest theaters. 
In view of this, it is natural to wonder what 
measurements have been made of the heat 
at the film aperture. 

Mr. Frey: As Mr. Sponable has already 
explained, the lamp has only recently 
been finished, so the values shown in the 
figure may not be final, but may be 
indicative. At exactly 150 amp we 
measured 48,000 lumens on the screen, 



that is screen lumens with a distribution 
of about 75%. In this case, the radiation 
energy at the center of the gate was 
1.25 w/sq mm, which is about 30% less 
heat per unit of light than with the con- 
ventional arc. This radiation energy 
produces 48,000 screen lumens, while the 
same radiation energy for a conventional 
arc would be about 35,000 screen lumens. 
Mr. Sponable: Some of you here might 
be interested in what we are going to do 
with a lamp of this type. It was originally 
designed for use with the Eidophor, and 
normally would have been finished when 
the commercial models of the Eidophor 
are ready later this fall. However, be- 
cause we have the problem of showing 
CinemaScope on very large screens, 
particularly drive-ins, the use of such a 
lamp seems to be a possible solution for 
the drive-in problem. 



532 



October 1953 Journal of the SMPTE Vol. 61 



Specifying and Measuring the Brightness 
of Motion Picture Screens 

By F. J. KOLB, JR. 



Screen brightness is measured and specified in order to control viewing 
conditions for projected pictures. By the modulation of light from the pro- 
jector the whole artistic creation captured in the production of a motion picture 
is presented to its ultimate audience. This creation can only equal the direc- 
tor's concept when viewing conditions are known and predictable. The 
control of screen brightness and the screen-image transfer characteristic is 
therefore a necessary condition for the most effective presentation of motion 
pictures. Brightness characteristics of projected pictures are discussed and 
the various practical simplifications considered. Nine conditions of screen- 
brightness measurement are described, specifications for the meters required 
are developed, and several simplified practical procedures for field measure- 
ment are detailed. 



I 



N 1941 the Subcommittee on Screen 
Brightness of the SMPE Theater Engi- 
neering Committee undertook the job 
of determining how screen brightness 
should be measured and of specifying 
instruments suitable for the job, so that 
it would be more convenient to obtain 
data and study the viewing conditions 
of theater projection. Valid informa- 
tion on current practices, the Com- 



A report prepared by the Subcommittee 
on Instruments and Procedures of the 
SMPTE Screen Brightness Committee. 
Subcommittee members are W. F. Little, 
A. Stimson, H. E. White and F. J. Kolb, 
Jr., Chairman. (Received for publication 
September 21, 1953.) 

Note: Nomenclature throughout this report 
follows ASA Z7. 1-1 942, "Illuminating 
Engineering Nomenclature and Photo- 
metric Standards." 



mittee felt, was essential before any 
fundamental review of the 1936 tempo- 
rary screen-brightness standards could be 
attempted, and before any improvement 
in theater viewing could be proposed. 

Preliminary work led to specifications 
for an Illumination Meter and a Bright- 
ness Meter; these specifications were 
published in the October 1941 Com- 
mittee report (Jour. SMPE, 38: 81-86, 
Jan. 1942). 

Little progress was made during the 
war on the development of commercial 
instruments to meet these specifications. 
The problems of screen brightness had 
become of sufficient importance, how- 
ever, that in the reorganization of the 
Society's committees, an independent 
Screen Brightness Committee was estab- 
lished in 1946. In March 1947 the 
Committee agreed to go ahead with what 



October 1953 Journal of the SMPTE Vol. 61 



533 



instruments were available, and de- 
termine the operating conditions in a 
small sample of theaters, in order to 
know what conditions would have to 
be met in a larger theater survey, to 
find out how well available instruments 
would perform, and to determine the 
practicality of surveying a significantly 
large number of the theaters at that 
time. Results of this preliminary survey 
were published in the Committee report 
of October 1947 (Jour. SMPE, 50: 
254-276, Mar. 1948). 

During the next four years the Com- 
mittee had several instruments sub- 
mitted for test, considered the limitations 
of equipment used in the 1947 survey, 
discussed what additional specifications 
should be formulated, and then under- 
took an enlarged theater survey using 
pilot-model instruments. The results 
of this survey eventually included more 
than 125 indoor theaters, divided among 
the various sizes of commercial theaters 
and located in several national geo- 
graphic areas; data were published in 
the Committee reports of May and 
October 1951 (Jour. SMPTE, 57: 238- 
246, Sept. 1951; and 57: 489-493, 
Nov. 1951). 

At the Committee Meeting on Feb- 
ruary 2, 1950, a Subcommittee on 
Instruments and Procedures was ap- 
pointed to review the problems of 
instrumentation and measurement. 
From the beginning it has been the 
purpose of this Subcommittee to express 
the instrumentation requirements for 
screen-brightness research and control, 
rather than to describe existing equip- 
ment. At succeeding meetings, the 
proposals of this Subcommittee have 
been discussed, modified and the intent 
re-examined, so that this report is 
presented as a statement and review of 
needs as they are presently understood. 

Significance of Screen Brightness 

Motion-picture films provide a form 
of visual art and communication de- 
pendent entirely upon the modulation 



of light. There is a sharp break in the 
presentation of motion pictures between 
the creative, preparatory work that 
produces a final image on motion- 
picture film, and the subsequent task 
of presenting this creation to the audience 
for whom it is intended. The director, 
producer and their staff cease any 
supervision of the project and turn the 
whole material over to the projectionist 
for him to present. Working solely with 
light to convey the visual content of 
this motion-picture film, the projectionist 
is concerned with the production of light, 
its concentration on the film, its modula- 
tion by the varying densities of the 
image, its collection in the projection 
lens, its reconvergence in an enlarged 
version of the photographic image, its 
re-emission from the projection screen, 
and finally its perception by the audience. 

The eventual success of the creative 
thought and work producing a motion 
picture is dependent upon the successful 
modulation of the projection light in the 
exact manner visualized by the director 
when he approved the final work print. 
Yet many factors in the final presenta- 
tion are subject to wide variation, be- 
yond the director's control. The maxi- 
mum brightness of the highlight areas in 
the picture as perceived by the audience 
is limited by the attainable screen bright- 
ness when the projector is operated with 
clear film in the gate; the minimum 
brightness of the shadow areas is limited 
by the stray and re-reflected light reach- 
ing the screen when the projector 
images an opaque target. Furthermore, 
the color of the screen light influences 
the faithfulness of screen reproduction, 
and the screen environment has great 
effect upon the illusion. These and 
similar factors together control the ap- 
parent contrast and mood of the picture, 
modify the highlight and shadow detail, 
determine the intelligibility of the picture 
information, and affect the psychological 
impact of the images. 

The artistic creation may be pre- 
sented effectively or poorly depending 



534 



October 1953 Journal of the SMPTE Vol. 61 



upon the control of the many factors of 
screen brightness, and upon their agree- 
ment with anticipated values. The 
present success of projected pictures is 
evidence that much has been accom- 
plished; even these successes have 
pointed out that much more is yet to 
be done. 

Characteristics of Screen Brightness 

Brightness of motion-picture screens 
is at first approach a simple subject and 
most of the measurements, treatments, 
and surveys have made enough assump- 
tions to realize this simplicity. When 
the complete problem is considered, 
however, there are many interacting 
physical factors that determine the 
ultimate audience perception of the 
visual image. While simplification is 
often permissible and even desirable, 
it is important to know at all times what 
assumptions have been made, and to remember 
that the brightness at a particular point on 
the motion-picture screen and the brightness 
differences across the screen depend upon the 
projector, the motion-picture film, the audi- 
torium, the screen and the position of the 
observer. 

Considering a single point on the 
screen, the brightness at that point depends 
upon (1) the brightness of projection 
source and the transmission loss, deter- 
mined by the projection equipment; 
(2) the loss during transmission of the 
beam to the projection screen (which is 
usually negligible) and the gain in 
brightness resulting from auxiliary light- 
ing in the auditorium and re-reflections 
of screen light and flare of projected 
light (which altogether may be ap- 
preciable); (3) the reflection charac- 
teristics of the screen, including not 
only its efficiency but also its response 
to incident illumination at an angle 
which is seldom 90, and its ability to 
direct energy along the variable re- 
flection angle toward the particular spot 
occupied by the observer in the audience. 
For any single observer in the audience 
the distribution of brightness across the 



screen depends further upon (4) the 
brightness distribution in the projection 
aperture; (5) the pattern of photo- 
graphic density on the motion-picture 
film; (6) the characteristics of the 
projection optics; and (7) the variation 
in angles of incidence and reflection 
from various portions of the screen 
surface. 

Relatively constant factors in this 
grouping are determined for any par- 
ticular theater by the equipment and 
the theater design. For example, the 
brightness of the projection source and 
the transmission losses of the complete 
optical system are practically constant 
for any measurements made in one 
specific theater. The gain in screen 
brightness from surround illumination 
and re-reflected light, has a constant 
component from the specific auditorium 
lighting, plus a variable component 
representing the re-reflected screen light. 
(This re-reflected light, of course, varies 
with changes in the subject matter on 
the screen.) The distribution of light 
incident upon the photographic image 
in the projection aperture is roughly 
predictable from the type of projection 
equipment and the details of its align- 
ment and adjustment. (This distribu- 
tion, however, may vary significantly 
with changes in the position of the 
carbons. With some equipment this 
variation is noticeable only if the arc 
control point tends to wander during the 
operating cycle; other equipment may 
be optically so critical that even constant 
attention of the projectionist to this one 
part of his duties may be insufficient 
to avoid measurable and noticeable 
changes in brightness distribution.) 

Chief variable factors are those which 
depend upon observer position in the 
audience, and of course upon density 
distribution in the photographic inter- 
mediate. 

For any projection screen the im- 
portance of specifying the angles at 
which light reaches the screen from the 
projector and the angles through which 



Kolb: Brightness of Motion-Picture Screens 



535 



light is reflected to reach the observer 
can be of extreme importance, as shown 
by Berger, 1 and D'Arcy and Lessman. 2 
Many times it has been assumed that 
motion-picture screens are perfect diffu- 
sers whose brightness is constant for all 
directions of viewing. It is further 
usual to go beyond the original limita- 
tions defining such diffusion, and to 
assume that the brightness is constant 
in all directions even though the screen 
is illuminated at some angle other than 
the normal to its surface. While some 
of the common motion-picture matte 
screens approximate such a behavior, 
it has been shown that many of the 
commercial matte screens are measur- 
ably different and actually that many 
screens are purposely designed to differ 
from such a perfect diffuser. Data 
presented by Lozier 3 show some com- 
mercial use of directional screens in 
motion-picture theaters; their use is 
presumed to be even more common in 
schools, industrial auditoriums, etc. 
Both the search for higher screen bright- 
nesses together with the development of 
practical commercial procedures for 
making directional screens may be 
expected to produce a more widespread 
use of such materials. Directional 
screens offer the advantage of controlling 
brightness as a function of the angles of 
incidence and reflection; they are 
difficult to measure and evaluate for 
the same reason. In any installation, 
the angles of incidence and reflection 
vary significantly for different areas on 
the screen from any one observer 
position, and they usually vary even 
more from one observer position to 
another in the audience. 

During the SMPTE screen-brightness 
surveys the theater screens were ex- 
amined visually for evidence of direc- 
tional reflection, but the classification 
was qualitative. It was possible, for 
example, to recognize the metalized 
screens, and data in these theaters are 
so identified. In most of the other 
theaters, however, directional effects of 



lesser magnitude presumably were not 
determined because the portable equip- 
ment commonly available does not con- 
veniently provide the data for describing 
such screens. 

Variations in subject matter and 
therefore of image transmission and 
distribution are, of course, not usually 
determined -by theater survey; this 
information can be obtained more con- 
veniently through laboratory measure- 
ments of properly chosen samples. In 
this report we shall limit ourselves to 
pointing out the importance of such 
information, together with the present 
lack of adequate data. Obviously it is 
never intended that the audience view 
a "bare screen," and bare-screen bright- 
nesses have no direct significance! 
Projected pictures themselves are the 
true interest of audiences, and the 
brightnesses of the pictures themselves 
are basically what measurement seeks 
to determine, and what standards intend 
to control. It may be true that varia- 
tions in film transmissions and in other 
factors relating bare screen to picture 
brightnesses occur less frequently, but 
they can be of considerable magnitude 
and it must be realized that they can 
appear at any time. 

Despite the convenience and frequent 
necessity of separating the film-trans- 
mission variable from the other factors, 
it has been shown that our knowledge 
of transmission factors is inadequate. 4 
This Committee recommends that a 
thorough study of picture densities 
be undertaken as an essential part of 
the screen-brightness problems. Par- 
ticularly when the motion-picture engi- 
neer calls upon those in other fields for 
assistance (as he must in any problem so 
complex as the viewing of projected 
pictures) it is important to delineate the 
assumptions and definitions of our com- 
mon ground. 

Finally, in this group of variables of 
unusual significance, one must always 
realize that the problem of screen bright- 
ness is at its simplest still a problem of 



536 



October 1953 Journal of the SMPTE Vol. 61 



tone reproduction. Not only is the 
maximum brightness of importance, but 
also the minimum brightness and 
the nature of the brightness scale in 
between. Control of screen brightness 
implies control of a transfer charac- 
teristic, relating the screen image to the 
original creative visual sensation. It has 
been customary to simplify the problem 
by assuming that control of maximum 
brightness simultaneously controlled the 
shape of the entire transfer characteristic, 
and for a certain class of theater designs 
there was a limited constancy. Pro- 
jected pictures are now viewed under 
such a range of conditions, however, 
that all the assumptions on viewing 
conditions must be checked to confirm 
their validity. 

Theater Measurement 
of Screen Brightness 

To answer the practical need for data 
on the viewing conditions for projected 
pictures, and to determine whether a 
particular installation is operating within 
the range of standards and recom- 
mendations, field measurements are 
necessary. These data are customarily 



obtained under conditions that involve 
many assumptions, made because of 
instrument limitations, necessity for 
minimizing measurement times, neces- 
sity for portability and independence 
from laboratory facilities, and other 
factors of general convenience. 

Table I summarizes some of the 
possible measurement procedures, speci- 
fies the cognate assumptions, and notes 
details of equipment and procedures. 
The more detailed measurements may 
be necessary for research workers; the 
less detailed measurements should in- 
terest practical projectionists. 

The Appendix presents in more detail 
the specifications for the instruments 
themselves,* and for procedures for 
their use, recommended by the Screen 
Brightness Committee. In many cases 
these specifications include the best 
present compromise between what would 
be desirable and what it is practical to 
obtain. This summary is intended as a 
reference for the Committee and the 
industry on the determination of screen 
brightness data, and as a guide for 
those who may be interested hi develop- 
ing more suitable instruments. 



APPENDIX 

Instruments and Procedures for the Measurement of Screen Brightness 



This presentation of instrument speci- 
fications and procedures for their use 
in the determination of motion-picture 
screen brightness has been prepared to 
provide more definite answers for two 
questions considered in the previous 
discussion : 

1. What quantities are to be measured, 
and how are the measurements to be 
made? 

2. What are adequate standards for 
judging the suitability of instruments? 

Essentially the presentation is a 
formulation of the discussions and ex- 
perience of the Screen Brightness Com- 
mittee, although in some matters of 
detail it has been necessary to infer 
which of the possibilities is preferred. 



The Proposed Specifications, presented 
below, for illumination, brightness, re- 
flectance, and luminous flux meters 
describe instruments which do not 
necessarily exist. 



* This memorandum was prepared before 
the widespread interest in three-dimen- 
sional projection using dual prints and 
polarized projection light; accordingly 
the instrument specifications do not include 
a discussion of apparent brightness for 
polarized viewers, or of determinations of 
depolarization. These problems are under 
study by another subcommittee of the 
SMPTE Screen Brightness Committee, 
which will make recommendations on 
these additional requirements of instru- 
mentation and measurement. 



Kolb: Brightness of Motion-Picture Screens 



537 



8 
o 


(1) This information, or its 
equivalent, is the ultimate 
basis for screen brightness 
standardization. It is usually 
not practical to determine it 
directly. 


(1) This procedure is recom- 
mended for research studies 
of screen brightness. 


(1) When the nature of the 
transfer characteristic for the 
installation being measured 
is known, then locations of 
the two ends of the curve 
determine the complete trans- 
fer characteristic. 


(1) Calculation of apparent 
screen brightness as a function 
of viewing angle usually is 
not attempted; most fre- 
quently the screen is assumed 
matte, with brightness inde- 
pendent of viewing angle. 


Procedure f 


( 1 ) Measure screen brightness 
as a function of film transmis- 
sion, of audience placement 
and of position on the screen. 


( 1 ) Measure screen brightness 
at selected, arbitrary film 
densities, as a function of 
audience placement and of 
position on the screen. 


( 1 ) Measure brightness of the 
bare screen and of the shielded 
screen as a function of audi- 
ence placement and of posi- 
tion on the screen. 


(1 ) Measure from one location 
in the audience, determining 
brightness of the bare screen 
as a function of position on 
the screen. 

(2} Measure from immediately 
in front of the screen, deter- 
mining normal brightness of 
the bare screen as a function 
of position on the screen. 




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538 



October 1953 Journal of the SMPTE Vol. 61 




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Kolb: Brightness of Motion-Picture Screens 



539 







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Assumptions 


Relative brightness know 
a function of projectio 
le and viewing angle. 


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540 



October 1953 Journal of the SMPTE Vol. 61 



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Kolb: Brightness of Motion-Picture Screens 



541 



It has been the intention to prescribe 
instruments that are both essential and 
desirable, attempting to strike a balance 
between what the Screen Brightness 
Committee has found necessary and 
what can reasonably be manufactured. 
Obviously the more complex research 
instrument specifications make little 
concession to ease of manufacture, while 
the less complex practical instruments 
have no reason for consideration unless 
they can be widely available at reason- 
able prices. In every case it has been 
necessary to balance the probable use 
of the data, the magnitude of other 
measurement errors, and the estimated 
cost of more stringent specifications. 
In the opinion of the Committee, these 
compromises are the most desirable that 
can now be selected. 

It is recognized further that much 
information has been accumulated and 
will continue to be obtained with 
instruments that do not meet these 
specifications. This report is not in- 
tended to discredit these instruments 
or data derived with them, but only to 
provide a standard for their evaluation. 
By indicating what variables may have 
influenced the results, and cautioning 
against unwarranted assumptions and 
conclusions, these specifications may 
help to make more useful the data from 
such nonconforming instruments. 

Recommended Procedures for the measure- 
ment of illumination, brightness, re- 
flectance, and luminous flux follow the 
general outline of the Screen Brightness 
Committee's Theater Surveys. These 
procedures, it will be noted, are con- 
cerned only with the problems of 
practical theater measurement and not 
the more complex research activities. 
The more precise data for controlled 



studies will be obtained by relatively 
few workers who are deeply engrossed 
in the subject, and who will want to 
work out their own procedures. These 
recommendations are intended solely 
for those who must add the measuring 
of screen brightness to many other 
problems and interests, and who will 
use the simpler instruments of necessity; 
for their use the Recommended Pro- 
cedures outline what measurements need 
be made and what instruments are 
required, plus necessary information on 
methods of measurement, calculations, 
and possible interference or complica- 
tions. 

At the beginning of the Committee's 
Theater Surveys it had been agreed 
that the measurement of screen illumi- 
nation convenient and straight- 
forward should be depended upon to 
provide the primary practical data, 
and that screen brightness should be 
calculated after determining a reflectance 
factor for computing brightness. It 
soon became obvious, however, that in 
many instances attempts to measure 
illumination at points on the screen 
a considerable distance above the stage 
or ground present real mechanical 
problems. On the assumption that 
auxiliary equipment sufficiently uni- 
versal to position the light-sensitive 
elements of illumination meters properly 
in every theater installation will not 
be common, the Committee has also 
considered measurements of total lumi- 
nous flux at the projector, in order to 
provide data that might otherwise be 
unobtainable. Finally, this report has 
been expanded to point out the real 
objective of screen brightness measure- 
ments, together with some of the pitfalls 
of oversimplification. 



542 



October 1953 Journal of the SMPTE Vol. 61 



Index to Specifications 
Spec. Title 

A Brightness Meter Audience-Type High Sensitivity 

B Brightness Meter Audience-Type 

C Brightness Meter Screen-Type 

D Illumination Meter Screen-Type 

E Gonioreflectometer 

F Reflectance Meter 

G Luminous Flux Meter Differential-Type 

H Luminous Flux Meter Integral-Type 



Page 

543 
544 
545 
546 
547 
548 
549 
550 



Index to Recommended Practices 

Recommended Practice for the Determination of Bare-Screen Brightness . 551 
Recommended Practice for the Measurement of Luminous Flux . . 554 



Specification A. Brightness Meter Audience-Type High Sensitivity* 



7. Purpose. An instrument to measure 
brightness of a motion-picture screen, 
for use from the audience, and of 
adequate sensitivity to measure the 
range of brightnesses defining the transfer 
characteristic of projected motion pic- 
tures, f 

2. Scope. This specification describes 
a light-sensitive cell which can be 
located within the audience area to 
receive the light reflected from a motion- 
picture screen's surface, a meter to 
indicate cell output, together with a 
suitable aiming device so that the 
brightness can be determined for a 
specific, small screen area. 

3. Useful Range. 0.005-60 ft-L; mul- 
tiple scales or logarithmic scale required. 

4. Accuracy. 

a. Initial Accuracy: 7% of the 
scale point within the upper half of the 
scale, and 7% of the midscale value 
within the lower half of the scale 
measured at 70 F with tungsten light 
at a color temperature of 2700 K. 
Scales shall be so chosen that any 
brightness within the useful range can 
be read with an initial accuracy of at 
least 15%. 

b. Temperature Sensitivity: Any 



change in indication resulting from a 
temperature change of d=20 F from the 
reference temperature of 70 F shall not 
exceed 12%. 

c. Fatigue: Negligible, providing cell 
has not been exposed to illumination 
in excess of 100 times the measured 
value within 10 min of measurement. 

d. Color Response: The sensitivity 
shall correspond to the standard lumi- 
nosity curve, such that the response 
curve of the cell shall be within that 
envelope whose ordinates are the stand- 
ard luminosity curve 5% of the 
maximum ordinate. 

e. Integration : The meter is intended 
for use with 48- to 72-cycle illumina- 
tion,! and a net integral shutter trans- 
mission of 30% - 70%. If under these 
conditions there is a frequency error 
a calibration curve shall be supplied. 

5. Response. Meter period and damp- 
ing shall be chosen to give a response 
time of less than 10 sec. Meter and cell 
shall be rugged, and resistant to a shock 
of 20 g. 

6. Acceptance Angle. This meter shall 
be shielded so that the 50% cutoff from 
a point source occurs at an acceptance 
angle no greater than 0.5. 



Kolb: Brightness of Motion-Picture Screens 



543 



7. Operation. 

a. Convenience: Instrument easily 
moved, located, and read by one man. 

b. Power: Self-contained power would 
be preferred, although 110-v, 60-cycle, 
a-c operation may be required. 

8. Probable Range of Values. 



c. Support: Sufficient for use of meter 
from the seating area of the auditorium. 
The supporting and aiming device 
should indicate viewing angles sufficient 
to describe the audience positions from 
which measurements are made. 



Indoor Theaters 



9 = Horizontal angle subtended by screen from 

theater midline 

^ = Horizontal viewing angle, to screen normal 
a = Vertical viewing angle, to screen normal 



Max. 

53 
65 
+45 



Min. 

9 



-10 



Outdoor Theaters 
Max. Min. 



35 6 


+40 +2 



Notes 

* This meter is intended to provide direct 
data on the brightness of projected pictures, 
and therefore must be used for extended 
periods of measurement to determine the 
variations in brightness over the picture 
area and the variations with subject 
matter. It is primarily a research instru- 
ment. 

f This meter will also be useful for measur- 
ing brightnesses of the screen surround, 
and of the audience areas of the theater. 



t Since current practice overwhelmingly 
favors intermittent projection, the meters 
for measuring the brightness of motion- 
picture screens must integrate a series of 
light pulses. Usually 35mm projection 
equipment provides 48 pulses/sec, while 
16mm projection equipment provides 72 
pulses/sec at "sound speed" and 48 
pulses/sec at "silent speed." The light 
pulses are interspersed with almost total 
darkness ; light pulses are of approximately 
equal duration and are approximately 
equally spaced in time. 



Specification B. Brightness Meter Audience-Type* 



7. Purpose. An instrument to measure 
brightness of a motion-picture screen 
from the audience area, of adequate 
sensitivity to measure the brightness 
of a bare screen. 

2. Scope. This specification describes 
a light-sensitive cell which can be located 
within the audience area to receive the 
light reflected from a motion-picture 
screen's surface, a meter to indicate 
cell output,f together with a suitable 
aiming device so that the brightness can 
be determined for a specific, small screen 
area. 

3. Useful Range. 0.2-60 ft-L. Multiple 
scales or logarithmic scale required. 

4. Accuracy. 

a. Initial Accuracy: Same as Spec. A. 



b. Temperature Sensitivity: Same as 
Spec. A. 

c. Fatigue: Negligible, providing cell 
has not been exposed to illumination in 
excess of 10 times the measured value 
within 10 min of measurement. 

d. Color Response : Same as Spec. A. 

e. Integration: Same as Spec. A. 

5. Response. Same as Spec. A. 

6. Acceptance Angle. This meter shall 
be shielded so that the 50% cut-off 
from a point source occurs at an ac- 
ceptance angle no greater than 1.5. 

7. Operation. Same as Spec. A. 

8. Probable Range of Values. Same as 
Spec. A. 



544 



October 1953 Journal of the SMPTE Vol. 61 



Notes 

* This specification describes a meter 

suitable for measuring screen brightness 

when the projector is operated normally 

except that no film is threaded into the 

gate. 

f ( lommittee experience has indicated 

that it is highly desirable for this instru- 



ment to be direct reading; there are 
several meters available that nearly meet 
these specifications, but require the sub- 
jective balancing of two illuminated fields. 
In these existing meters, the two fields are 
usually of different colors and different 
observers frequently disagree in their 
choice of balance readings. 



Specification C. Brightness Meter Screen-Type* 



7. Purpose. An instrument to measure 
point-to-point normal brightness of a 
motion-picture screen, of adequate sensi- 
tivity to measure the brightness of a 
bare screen. f 

2. Scope. This specification describes 
a light-sensitive cell which can be 
located within a few feet of the screen 
face to receive the light reflected from a 
motion-picture screen's surface, a meter 
to indicate cell output, together with a 
suitable support to position the cell in 
the desired location in front of the 
screen. 

3. Useful Range. Same as Spec. B. 

4. Accuracy. Same as Spec. B. 

5. Response. Same as Spec. A. 

6. Acceptance Angle. This meter shall 
be shielded so that the 50% cut-off 
from a point source occurs at an ac- 
ceptance angle no greater than 35; 
it is assumed that the meter will be 
used at a distance from the screen of 
2-3 ft. For meters intended to be 
used at greater distances, the locus of 
the 50% cut-off shall enclose a screen 
area no larger than that permitted 
above. 

7. Operation. 

a. Convenience: Instrument easily 
moved, located, and read by one man. 

b. Power: Self-contained power pre- 
ferred. 

c. Support: Support must be portable 



in a passenger automobile, it must be 
capable of being assembled and operated 
by one man, and it must support the 
cell at any location before the screen 
without danger of contact or injury to 
the screen surface. 

8. Probable Range of Values. The 
following table lists the range of variables 
normally expected. Symbols refer to 
the drawing in "Recommended Practice 
for the Determination of Bare-Screen 
Brightness." 

Indoor Drive-In 

Theaters Theaters 

Max. Min.% Max. Min.% 

H Ft 30 9 52.5 22.5 

W Ft 40 12 70 30 

N Ft 10 2 25 10 

B A Ft-L 30 4 20 2 

Be Ft-L 28 1 15 0.5 

Reflectance % 100|| 35 80 30 
Perforated 

Screen Yes No 

Notes 

* This specification describes a meter of 
general usefulness, comparable in applica- 
tion and results to Specification B except 
that less information is obtained about the 
variations in brightness with changes in 
the viewing angles. The choice between 
these two meters will probably be made on 
the basis of availability, convenience and 
the frequency of occurrence of directional 
screens. 

t This meter's practical usefulness is limited 
to the measurement of screens that are 
matte, or nearly perfect diffusers. Its 
results with directional screens can be 
interpreted accurately only after careful 



Kolb: Brightness of Motion-Picture Screens 



545 



calibration with the specific directional 
screen measured. 

J The minimum value of brightness 
quoted in section 8 "Probable Range of 
Values" assumes low reflectance of the 
screen combined with measurements in a 
corner of the screen. If measurements 
are made at the geometric center, this 
minimum expected brightness can be 
increased by 100% or more. 
These screen widths are based upon a 



picture aspect ratio of 1.33. At the 
present time there is consideration of 
larger aspect ratios at least up to 2.85, 
which may increase the values of "W" 
without changing maximum values of 
"H." 

|| Apparent reflectance values of 100% or 
more may occur with screens having some 
directional effect; in the 1951 Theater 
Survey several screens with apparent 
brightness gains up to 200% were found. 



Specification D. Illumination Meter* 



7. Purpose. An instrument to measure 
point-to-point illumination at the mo- 
tion-picture screen, and to determine 
illumination distribution, f 

2. Scope. These specifications describe 
a light-sensitive cell which can be 
located to intercept light falling on any 
part of a motion-picture screen's surface, 
a meter to read cell output located where 
it can be read by an observer at the base 
of the screen, and a support to position 
the cell in the desired place in front of 
the screen. 

3. Useful Range. Low scale, 0.5-30 
ft-c. High scale, 2-60 ft-c. 

4. Accuracy. 

a. Initial Accuracy : Same as Spec. A. 

b. Temperature Sensitivity: Same as 
Spec. A. 

c. Fatigue: Same as Spec. B. 

d. Color Response: Same as Spec. A. 

e. Integration: Same as Spec. A. 

5. Response. Same as Spec. A. 

6. Operation. 

a. Convenience: Instrument easily 
moved, located, and read by one man. 

b. Power: Self-contained power pre- 
ferred. 

c. Support: Support must be portable 
in a passenger automobile, it must be 
capable of being assembled and operated 
by one man, and it must support the cell 



at any point on the screen without danger 
of contact or injury to the screen surface. 
(If the support holds the cell at an 
appreciable distance forward of the 
screen, an inverse square law correction 
will need to be made on illumination 
values.) 

7. Probable Range of Values. The 
following tablet lists the range of 
variables normally expected. Symbols 
refer to the drawing in "Recommended 
Practice for the Determination of Bare- 
Screen Brightness." 

Indoor Drive-In 

Theaters Theaters 

Max. Min. Max. Min. 



H Ft 


30 


9 


52.5 


22.5 


W Ft 


40 


12 


70 


30 


N Ft 


10 


2 


25 


10 


E A Ft-c 


40 


5 


27 


2.7 


EC Ft-c 


37 


1.3 


20 


0.7 


Reflectance 


100 


35 


80 


30 


Perforated 











Screen 



Yes 



No 



Notes 

* This is considered the basic instrument 

for the practical measurement of projection 

conditions in the theater. At the present 

stage of instrument development, it appears 

that this instrument is most likely to be 

the one generally available. 

t This specification describes a meter 

suitable for measuring screen illumination 

only. The Screen Brightness Committee, 

however, has indicated that eventually 



546 



October 1953 Journal of the SMPTE Vol. 61 



some meter for measuring the illumination 
of the screen surround will be necessary 
in order to control picture perception. 
This meter plus that described in Spec. A 
are the only two appropriate and this 
meter could be used only if its Useful Range 
could be extended to 0.01-60 ft-c. There 
is a slight advantage in measuring surround 
illumination rather than surround bright- 
ness, because most of the screen surround 
makes use of surfaces of low reflectance 
and therefore measurements of illumina- 



tion do not require as great sensitivity to 
low signal. 

J This table is a restatement of the corre- 
sponding table in Spec. G, revised to give 
approximate illumination values instead 
of brightness values. 

These screen widths are based upon a 
picture aspect ratio of 1.33. At the 
present time there is consideration of 
larger aspect ratios at least up to 2.85, 
which may increase the values of <% W" 
without changing maximum values of 
"H." 



Specification E. Gonioreflectometer* 



7. Purpose. An instrument to measure 
specular reflectancef of motion-picture 
screens as a function of viewing angle, 
for use in conjunction with measure- 
ments of illumination. 

2. Scope. This specification describes 
a light-sensitive element receiving light 
reflected from the screen, a standard 
source illuminating the screen (or pro- 
vision to use a standard projector), 
a meter indicating response of the light- 
sensitive element, together with a mecha- 
nism for holding these components in 
proper relationship and indicating their 
relative angles. 

3. Useful Range. Reflection factor 0.01 
to 10.J 

4. Accuracy. 

a. Initial Accuracy: Same as Spec. A. 

b. Temperature Sensitivity: Same as 
Spec. A. 

c. Fatigue: Same as Spec. A. 

d. Color Response: Same as Spec. A. 

e. Integration: If the meter is de- 
signed to provide its own standard 
source of illumination the source may 
be continuously excited and no inter- 
mittency problem results. If on the 
other hand the meter uses the light from 
a standard projector, its integration 
performance should be the same as 
Specification A. 



f. Measuring Illumination. Reflect- 
ance shall be measured with light of a 
quality approximating a color tempera- 
ture of 2700 K., or with light of high- 
intensity arc quality. 

5. Response. Same as Spec. A. 

6. Field of View. 

a. Measuring Illumination: The inci- 
dent illumination shall be specular, 
with the light confined to a cone of not 
more than 0.5 included angle. 

b. Acceptance Angle: The light-sensi- 
tive cell shall be shielded so that the 
50% cut-off from a point source occurs 
at an acceptance angle no greater than 
0.5. 

c. Area Measured: The screen sur- 
face measured for reflectance shall be 
greater than 0.2 sq ft but less than 
4 sq ft. 

7. Angle of Reflection. The light- 
sensitive element shall be adjustable to 
measure reflectance through the range 
of illumination angles in section 9 of this 
specification and of viewing angles in 
section 8 in Spec. A. 

8. Operation. 

a. Convenience: Same as Spec. D. 

b. Power: Self-contained power is 
preferred. If necessary for the proper 
balance of performance and portability 



Kolb: Brightness of Motion-Picture Screens 



547 



to use external power (for example to 
provide a self-contained source of illumi- 
nation) an instrument operating on 
110-v, a-c-d-c can be used. 

c. Support: Since it will be sufficient 
to measure reflectance at a limited 
number of locations on the screen, it 
will not be necessary to cover the full 
range of screen area required for Spec. 
D. It would be a convenience in many 
cases, however, to use the same support 
therein described. 

9. Probable Range of Values. Same as 
Specs. A and C, plus: 

Max. Min. 

<f) V = Vertical projection 

angle 25 

H = Horizontal projec- 
tion angle d= 5 

Notes 

* There are two possible use patterns for 
a motion-picture screen gonioreflectom- 
eter: Measurement in the theater, and 
measurement in the laboratory. In either 
event it is expected that this will be 
primarily a research instrument, and that 
there will never be a great number con- 



structed. At present it seems more 
likely that the laboratory usage is the more 
probable, and in this case the requirements 
that have to do primarily with portability 
(section 8 of this specification) can be 
disregarded. No other distinction between 
the two use patterns seems desirable. 
t Specular Reflectance is important for 
motion-picture screen performance be- 
cause for any one position on the screen, 
the base of the incident light cone is the 
exit pupil of the projection lens, and the 
base of the reflected light cone is circum- 
scribed around the observer's eyes at any 
one viewing position. (Diffuse reflection 
is only useful as an approximation, when 
the screen surface is nearly matte and no 
investigation is made of angular dis- 
tribution. 

J A wide range of reflectance values may 
be expected. For matte screens there is 
variation from the low values of de- 
teriorated screen surfaces, through the 
medium values of the weather-resistant 
surfaces of outdoor theaters, to the high 
values of new indoor screens. For direc- 
tional screens there is variation from the 
very low values of off-angle reflection to 
the very high values in the direction of 
maximum efficiency. 



* Specification F. Reflectance Meter 5 



7. Purpose. An instrument to measure 
normal reflectance of motion-picture 
screens, for use in estimating brightness 
from measurements of illumination. 
Usefulness of this instrument is prac- 
tically confined to the measurement of 
matte screens, f 

2. Scope. This specification describes 
a light-sensitive element receiving light 
reflected from the screen, a standard 
source illuminating the screen, a meter 
indicating response of the light-sensitive 
element, together with a mechanism 
for holding these components in proper 
relationship. 

3. Useful Range. 30-120% reflectance. 

4. Accuracy. Same as Spec. E. 



5. Response. Same as Spec. A. 

6. Field of View. 

a. Measuring Illumination: The inci- 
dent illumination shall be specular, 
with the light confined to a cone of not 
more than 1.5 included angle. 

b. Acceptance Angle: The light-sensi- 
tive cell shall be shielded so that the 
50% cut-off from a point source occurs 
at an acceptance angle not greater than 
1.5. 

c. Area Measured : The screen surface 
measured for reflectance shall be greater 
than 0.2 sq ft but less than 4 sq ft. 

7. Angle of Reflectance. The light 
illuminating the screen shall be normal 
to its surface. The angle between the 
light-sensitive element and the normal 



548 



October 1953 Journal of the SMPTE Vol. 61 



to the center of the test area shall be 
approximately 10.{ 

8. Operation. Same as Spec. E. 

9. Probable Range of Values. Same as 
Spec. E. 

Notes 

* In contrast to the gonioreflectometer of 
Spec. E, this instrument is intended almost 
exclusively for use in the theater. There- 
fore, the requirements for portability, etc. 
cannot be compromised. 
f It would be possible to study a particular 



motion-picture screen with more refined 
equipment to obtain a calibration so that 
this particular instrument's readings could 
be converted to a complete specification 
of angular response. The difficulties of 
this task, however, make it desirable to 
confine this meter to screens that may be 
considered diffuse scatterers. 
J It would be a convenience if this instru- 
ment could measure interchangeably both 
the specular reflectance specified, and the 
total diffuse reflectance from the same 
light source. With such an instrument the 
two reflectances could be compared to 
indicate immediately when the screen 
was matte or directional. 



Specification G. Luminous Flux Meter Differential-Type* 



7. Purpose. An instrument to measure 
luminous output at the projector, and 
to indicate the relative intensities of the 
pencils of light directed to specific loca- 
tions on the screen. This meter is 
intended for use primarily when physical 
conditions and the instruments available 
prevent measurements at the screen. f 

2. Scope. This specification describes 
a light-sensitive cell which can be 
located to intercept the total luminous 
output from the projection lens (or a 
predetermined portion of that total 
output), a meter to read cell output, 
and any necessary appurtenances for 
their use. Specifically included are 
necessary masks or other devices to be 
inserted into the projector aperture 
and focused on the screen,t in order 
to sample particular screen areas for 
measurement of light flux. This meter 
will be used either immediately at the 
lens exit within the projection booth, or 
immediately beyond the projection port 
just outside the projection booth. 

3. Useful Range. 100-20,000 lumens 
multiple scales or logarithmic scales 
required. 

4. Accuracy. Same as Spec. A. 



5. Response. Same as Spec. A. 

6. Scanned Area. As a minimum the 
meter must read luminous flux to each 
of the five measuring areas specified 
in "Recommended Practice for the De- 
termination of Bare-Screen Brightness." 
Each pencil shall intercept at the screen 
no more than 1% of the illuminated 
screen area. 

7. Operation. 

a. Convenience: Instrument easily 
moved, located, and read by one man. 

b. Power: Self-contained power pre- 
ferred. 110-v, a-c will be available, 
however. 

c. Support: In all cases the instru- 
ment and any supporting structures 
must be portable in a passenger auto- 
mobile, transportable through a pro- 
jection-room door, and it must be 
capable of being assembled and operated 
by one man. When intended for use 
within the projection booth any support 
must not interfere with the projector 
mechanism, or be limited by the front 
wall or port of the booth. When in- 
tended for use outside the projection 
booth, suitable support for the instru- 
ment to position it firmly will probably 
be required. 



Kolb: Brightness of Motion-Picture Screens 



549 



8. Probable Range of Values. The fol- 
lowing table lists the range of variables 
normally expected. Symbols refer to 
the drawing in "Recommended Practice 
for the Measurement of Luminous Flux." 

Indoor and Outdoor 

Theaters 
Value Max. Min. 

D In. 4.00 2.03 

S In. 24 6 

2 Degrees 24 5 

F Lumens total flux 20,000 200 

N Ft 20 2 

Notes 

* This meter is relatively simple in opera- 
tion and probably such that a regular 
projector serviceman could include it 
in his kit. There is much to be gained 
by research studies of screen brightness, 



but perhaps equally important is the 
practical gain from proper servicing of 
equipment; convenient measurement is a 
prerequisite for adequate servicing. 

f Screen brightness and illumination are 
considered functions of the masked area of 
the screen, whereas this meter measures in 
terms of the total illuminated area. Any 
significant difference between masked and 
total area must be noted, because it will 
affect not only the total flux transmitted, 
but also the relative positions of the 
measuring areas sampled from the total 
screen. 

J A standard projector aperture is assumed. 
Any departure from this standard must 
be noted. 

These values of luminous flux are mean 
net values, integrated over a sufficient time 
to damp out the flicker of intermittent 
projection. 



Specification H. Luminous Flux Meter Integral-Type* 



7. Purpose. An instrument to measure 
total luminous output at the projector 
when physical conditions prevent meas- 
urements of intensity and distribution 
at the screen. Because of the failure to 
provide some of the important data, 
this meter and method of measurement 
are proposed only to provide some 
information when otherwise there would 
be none available, f 

2. Scope. These specifications describe 
a light-sensitive cell which can be located 
to intercept the total luminous output 
from the projection lens (or a truly 
representative portion of that total 
output), J a meter to read cell output, 
and any necessary appurtenances for 
their use. This meter will be used either 
immediately at the lens exit within the 
projection booth, or immediately be- 
yond the projection port just outside the 
projection booth. 

3. Useful Range. 1000-20,000 lumens. 



4. Accuracy. Same as Spec. A. 

5. Response. Same as Spec. A. 

6. Operation. Same as spec. G. 



Notes 

* This meter is one of the most simple for 

control of screen brightness. It would 

be desirable to have this an inexpensive 

instrument available in all the better 

projection rooms. 

f Screen brightness and illumination are 

considered functions of the masked area 

of the screen, whereas this meter measures 

total illuminated area. Any significant 

difference between masked and total 

area must be noted. 

J A standard projector aperture is assumed. 

Any departure from this standard must 

be noted. 

These values of luminous flux are mean 

net values, integrated over a sufficient time 

to damp out the flicker of intermittent 

projection. 



550 



October 1953 Journal of the SMPTE Vol. 61 



Recommended Practice for the Determination of Bare-Screen Brightness 








I. Purpose 

This procedure describes practical 
methods for the determination of screen 
brightness when it is convenient to 
obtain data on screen illumination. 
Limitations on instruments commonly 
available make this indirect method the 
most generally useful for measurements 
in the theater. 

There are three parts to the pro- 
cedure: (1) Determination of illumi- 
nation and illumination distribution, 
(2) Determination of screen reflectance, 
and (3) Determination of screen bright- 
ness at one selected point. Determina- 
tion of brightness and brightness dis- 
tribution relies upon the data of (1) 
plus that of either (2) or (3). 

II. Measurement of Illumination 

A. Description. This procedure gives a 



satisfactory measure of screen illumina- 
tion for the average theater, with 
the projection system in good adjustment. 
It describes the determination of screen 
illumination and its variation over the 
screen surface, together with the cal- 
culation of total effective luminous 
output of the projector. It is assumed 
that these data will be basic for any 
theater evaluation of projection viewing 
conditions. 

B. Meter Specification. D 

C. Data. The projector and light 
source should be operated normally, 
with no film in the gate. 

1 . Measure H and W the height 
and average width of the masked area. 

2. Note whether there is any pro- 
nounced variation in color of illumina- 
tion across the screen.* 



Kolb: Brightness of Motion-Picture Screens 



551 



3. Read illumination on the screen 
in ft-c at positions A, BI, B 2 , Ci, and 
C 2 , using a meter that conforms to 
"Specification D. Illumination Meter." 

4. If E Bl varies from E B2 by more 
than 50%, or E Cl varies from E C2 
by more than 50%, the illumination is 
sufficiently unbalanced that calculated 
results will be approximate only.* 

D. Calculations.^ 

5. Illuminated Screen Area: Area in 
square feet = S = H X W. 

6. Screen Light Distribution: Side- 

center ratio = R 8 = EB * + E * 2 X -. 
2 EA 



Corner-center ratio = R c = 



EC, -f- E 



c 2 



7. Total Screen Lumens :J 
E A X 2 

EBJ + Ee 2 = 
i(E Cl + E C2 ) = 



Total 

Weighted Average = F = i (Total) 

Screen Lumens = F X S 

E. Notes 

* If the light beam is decentered, the 
distribution is poorly chosen, or the equip- 
ment is in maladjustment, then the data 
will indicate how the theater was operat- 
ing, but it will be difficult to draw other 
valid conclusions. Variations in color 
of screen light usually indicate that the 
optical system components are out of 
position. Unbalance, as defined in G 
section 4 usually indicates poor centering, 
in which case E A will not be the maximum 
illumination, and the weighting factors 
for total flux will not be correct. 
t If the projector has a nonstandard 
aperture, or if the illuminated area is 
significantly larger than the masked screen 
area, then the useful screen lumens may 
be appreciably less than the total projector 
output. Excessive masking will also tend 
to improve light distribution because the 
fall-off becomes more rapid at the edge of 



the aperture. Significant differences be- 
tween lighted area and screen area may be 
expected when projection angles are 
steep unless this problem is concealed 
by the use of a nonstandard, trapezoidal 
aperture. 

| The weighting factors in section 7 
recommended for estimating total screen 
lumens from the 5-point measurements 
may be corrected slightly as more data 
are analyzed. 

III. Measurement of Reflectance 

A. Description. This procedure will 
measure screen reflectance for screens 
which are essentially matte.* In general 
it is intended to permit use of less 
expensive and sensitive instruments, 
which therefore may need more light on 
the screen than is supplied by a pro- 
jection beam perhaps requiring an 
auxiliary light source up close to the 
screen and meter. Constancy of re- 
flectance over the screen surface is 
assumed, f The data are intended for 
use in calculating screen brightness from 
screen illumination. 

B. Meter Specification. F 

C. Data. 

1. Examine the screen for qualitative 
evidence of nondiffuse reflection, and of 
variation in reflectance over the screen 
surface. t 

2. Measure reflectance at one point 
on the screen (preferably the geometric 
center if convenient). 

D. Calculations. 

3. p = Apparent Reflectance, meas- 
ured in 2 above. 

E. Notes 

* For matte screens which are essentially 
perfect diffusers, readings of the Re- 
flectometer Specification F indicate the 
screen reflectance reasonably well. Be- 
cause this reflectance is a constant inde- 
pendent of viewing angle, the value is 
applicable for estimating brightness as 



552 



October 1953 Journal of the SMPTE Vol. 61 



perceived from any audience position. If 
the screen does not approximate a perfect 
diffuser, then the determination of re- 
flectance is much more laborious, 
f Screen Reflectance as herein considered 
is an integrated value. It is based upon 
a section of screen small enough to be 
convenient to measure, and in practice to 
have constant illumination, but large 
enough to average the perforated and 
nonperforated areas of the screen. 
J Although substantially diffuse reflectance 
constant over the whole screen is a pre- 
requisite and is frequently assumed (and 
this is consistent with most of the data 
from the Theater Survey) there is indica- 
tion that controlled-reflection screens will 
become more numerous. For such screens 
it is essential that one determine reflectance 
as a polar function of viewing angle. 
Visual inspection or a simple check with 
the meter described in this Procedure will 
detect any wide departure from the usual 
reflectance pattern. Data from such 
screens should be clearly identified so 
that the results are not misinterpreted. 
The screen property measured is more 
properly called "Apparent Reflectance," 
because it is the ratio of the brightness of 
the screen as seen at a given viewing angle, 
to the brightness of a perfect diffuser 
illuminated with the same incident flux. 
The foot-lambert unit of brightness is so 
defined that a perfect diffuser illuminated 
by a flux of 1 ft-candle has an apparent 
brightness in any direction of 1 ft-lambert. 

Therefore 

p = Apparent Reflectance = 

B Brightness 
E Illumination 

IV. Measurement of Brightness 

A. Description. This method is to be 
used when a Brightness Meter is avail- 
able, of adequate sensitivity and re- 
sponse. Brightness is measured when 
the screen is illuminated by the pro- 
jection light. 

B. Meter Specification. B* or Cf 

C. Data. 

1. Examine the screen for qualitative 



evidence of nondiffuse reflection and of 
variation in reflectance over the screen 
surface.! 

2. Measure Screen Brightness at one 
point on the screen (preferably the 
geometric ccnter)t using a meter that 
conforms to Spec. B or Spec. ( !. 

3. Measure Screen Illumination at 
the same point, within 1 mm or less to 
minimize light fluctuations, using a 
meter that conforms to "Specification D. 
Illumination Meter." 

D. Calculations. 

4. PA = Apparent Reflectance at 

A 
B A Brightness at A 



_ _ 



E. Notes 



Illumination at A. 



* If a meter of Type B is available, it 
would be possible to complete the measure- 
ment of brightness distribution using only 
this instrument and reading directly. 
f Meters of Type C measure the inte- 
grated brightness over so large an area 
that measurements made near the screen 
border are frequently in error because 
the meter "sees" the dark border. Conse- 
quently in order to provide distribution 
data, the distribution of illumination 
(Part II) is relied upon to indicate the 
distribution pattern of brightness too. 
t This procedure in this simplified form 
is intended only for matte screens, approxi- 
mating perfect diffusers. Also see Part 
III, Note J. 
See Part III, Note . 

V. Calculation of Brightness and 
Brightness Distribution 

A. Description. This calculation is 
intended to give values of bare screen 
brightness for determining conformance 
to ASA Standard PH22.39-1952, for 
determining the side-center and corner- 
center brightness distributions, and for 
estimating the adequacy of picture 
viewing conditions. 

B. Prerequisites. It will be necessary 
first to complete Part II and either 



Kolb: Brightness of Motion-Picture Screens 



553 



Part III or Part IV of this procedure. B B , + B B2 1 



C. Data. 

1 . Illumination at the specified points 
(from Part II) 

E A , EBI, E B2 , Eci, and E C2 

2. Apparent Reflectance (from Part 
III or IV) 

PA (or pc if only this can be measured 
conveniently)* 

D. Calculations. 

3. B A = Brightness of screen at Af = 
p X EA = (Apparent Reflectance) X 
(Illumination at A). 

4. B Bl = p X E Bl , etc. 

5. V 8 = side-center ratiot = 



X . V = corner-center 
2 B A 

BCI + B C 2 . , 1 
ratio* = -- - -- X . 



E. Notes 

* It is assumed in this procedure that 
p = Apparent Reflectance, is constant 
over the whole screen surface, and is 
independent of viewing angle. 
f This center brightness is the only quan- 
tity specified in ASA Standard for Screen 
Brightness PH22.39-1952. 
t It will be apparent that since the screen 
is assumed to be a perfect diffuser, these 
brightness ratios will be numerically equal 
to the illumination ratios calculated in 
Part II. 



Recommended Practice for the Measurement of Luminous Flux 



VZZZZ^^ 




554 



October 1953 Journal of the SMPTE Vol. 61 



I. Purpose 

This procedure describes a method of 
determining the total luminous output 
of the projector when it is inconvenient 
or undesirable to obtain data at the 
screen (cf. "Recommended Practice for 
the Determination of Bare-Screen Bright- 
ness"). From the measurement of 
Luminous Flux it is possible to check 
projector alignment and operation. 
With certain assumptions it is also 
possible to estimate screen brightness. 
This procedure will be most useful for 
projector adjustment and repair, and 
for checking the constancy of projector 
performance. 

In some of the larger outdoor theaters 
and in a few indoor theaters, screen 
size and construction makes it extremely 
difficult to support a brightness or 
illumination measuring cell at many of 
the specified locations at the screen 
surface (cf. Instruments of Spec. C or 
D). This procedure therefore fills 
the need of supplying some "screen 
brightness" data when otherwise none 
would be available. Measurements 
are made with the projector and light 
source operated normally, except that 
no film is run through the gate. 

Measurements of Luminous Flux can 
be made with meters of Specification G 
or H. When estimates of screen bright- 
ness are desired, measurements should 
be made with the Type G; since meters 
of Specification H do not indicate the 
variation in illumination intensity over 
the screen area, and only average 
illumination can be determined. To 
determine conformance to the Screen 
Brightness Standard ASA PH22.39- 
1952, center brightness must be known. 

II. Measurement of Illumination: 
Meter Type G 

A. Data. 

1. Focus the projector normally on 
the screen. Examine screen for quali- 
tative evidence of nonsymmetrical light- 
ing, abnormal distribution, or variation 
in color of illumination.* 



2. Measure total luminous flux leav- 
ing the projection lens. 

3. Insert masks in projection aperture f 
and measure relative illumination to 
each of the 5 locations included in 
"Recommended Practice for the 
Determination of Bare-Screen Bright' 
ness." 

B. Calculations. 

4. Total Screen Lumens: read directly 
from 2 above. 

5. Center Screen Illumination: read di- 
rectly from 3 above with the mask 
corresponding to position "A." 

6. Screen Light Distribution: calculated 
from the readings of 3 above. 

Side-Center Ratio R 8 = EB! * 



X - 



Corner-Center Ratio R c = 

EC. + E C2 



1 

< E A 



7. Average Screen Illumination: calcu- 
lated from the readings of 3 above, 
using the weighting factors given in 
Part II, Section D-7, of "Recommended 
Practice for the Determination of Bare- 
Screen Brightness. 

8. Screen Brightness^ : Brightness corre- 
sponding to the illumination values of 5, 
6, and 7 above can be calculated by the 
method of Part V "Recommended 
Practice for the Determination of Bare- 
Screen Brightness" providing that re- 
flectance has been measured or is known. 

G. Notes 

* This procedure will determine satis- 
factorily the total luminous output of the 
projector. If the system is in good adjust- 
ment this value has significance. If the 
light beam is decentered, the distribution 
is poorly chosen, or the equipment is in 
maladjustment, however, the results will 
be difficult to interpret. Nonsymmetrical 
lighting is wasteful of light, poorly chosen 
distribution impairs either total illumi- 
nation or picture quality, color variations 
in illumination usually result from poor 
positioning of the optical system com- 
ponents. 



Kolb: Brightness of Motion-Picture Screens 



555 



I These measurements relate to the stand- 
ard projector aperture. If the aperture 
is nonstandard, or if the illuminated area 
overlaps the screen border significantly, 
these data on total output may not reflect 
properly the useful light directed to the 
picture area of the screen. 
J Inasmuch as the present Screen Bright- 
ness Standard specifies only the brightness 
as the center of the screen without mention 
of distribution, it will be necessary to 
calculate center brightness to determine 
conformance to standards. Average bright- 
ness has not been standardized. 

III. Measurement of Luminous Flux: 
Meter Type H 

A. Data. 

1 . Focus the projector normally on the 
screen. Examine screen for qualitative 
evidence of nonsymmetrical lighting or 
abnormal distribution.* 

2. Measure total luminous flux leaving 
the projection lens.f 

B. Calculations. 

3. Total Screen Lumens: are read 
directly. 

4. Average Screen Illumination: can 
be calculated if the illuminated area is 
measured. 

5. Average Screen Brightness! corre- 
sponding to the average illumination of 
4 above, can be calculated by the 
method of Part V "Recommended 
Practice for the Determination of Bare- 
Screen Brightness" providing that re- 
flectance has been measured or is 
known. 

C. Notes 

* This procedure will determine satis- 



factorily the total luminous output of the 
projector. If the system is in good adjust- 
ment this value has significance. If the 
light beam is decentered, the distribution 
is poorly chosen, or the equipment is in 
maladjustment, however, the results will 
be difficult to interpret. Nonsymmetrical 
lighting is wasteful of light, poorly chosen 
distribution impairs either total illumi- 
nation or picture quality, color variations 
in illumination usually result from poor 
positioning of the optical system com- 
ponents. 

t These measurements relate to the stand- 
ard projector aperture. If the aperture 
is nonstandard, or if the illuminated area 
overlaps the screen border significantly, 
these data on total output may not reflect 
properly the useful light directed to the 
picture area of the screen. 
| Inasmuch as the present Screen Bright- 
ness Standard specifies only the brightness 
at the center of the screen without mention 
of distribution, it will be necessary to 
calculate center brightness to determine 
conformance to standards. Average bright- 
ness has not been standardized. 

References 

1. F. B. Berger, "Characteristics of motion 
picture and television screens," Jour. 
SMPTE, 55: 131-146, Aug. 1950. 

2. Ellis W. D'Arcy and Gerhard Lessman, 
"Objective evaluation of projection 
screens," presented on April 22, 1952, 
at the Society's Convention at Chicago. 

3. W. W. Lozier, "Report of the Screen 
Brightness Committee," Jour. SMPTE, 
57: 238-246, Sept. 1951. 

4. F. J. Kolb, Jr., "The scientific basis 
for establishing brightness of motion 
picture screens a discussion of screen 
brightness," Jour. SMPTE, 54: 433- 
442, Apr. 1951. 



556 



October 1953 Journal of the SMPTE Vol. 61 



Proposed Revision, PH22.58 and PH22.59 
Apertures for 35mm Projectors and Cameras 



PROPOSED REVISIONS of two American 
Standards are published on the following 
pages for three-month trial and criticism. 
All comments should be sent to Henry 
Kogel, SMPTE Staff Engineer, prior to 
January 15, 1954. If no further revisions 
are recommended, the two proposals will 
then be submitted to ASA Sectional Com- 
mittee PH22 for further processing as 
American Standards. 

While these two standards on projector 
and camera apertures, PH22.58 and 
PH22.59, deal only with the old 1.33 
aspect ratio, it is nonetheless important 
that they be kept on the books and brought 
up to date because large segments of the 
motion-picture industry, both at home 
and abroad, are still making and pro- 
jecting motion pictures in accord with 
these standards. In addition all motion 
pictures made for television are based 
upon them. 

An earlier proposed revision of the 
projector aperture standard was published 
for trial and comment in the June 1953 
Journal and it is instructive to repeat the 
accompanying explanatory introduction. 

"In reviewing PH22.58, the Film Pro- 
jection Practice Committee came to the 
conclusion that the camera centerline 
should be deleted as well as dimension H 
which specified the 6-mil differential 
between camera and projector centerlines. 
The 6-mil differential was originally 
inserted to make allowance for film 
shrinkage so that the release print, after 



shrinking its normal amount, would have 
the image centered in the projector aper- 
ture. The decrease in the shrinkage 
characteristic of film eliminates the need 
for this differential, and now permits the 
use of the projector aperture centerline 
for both the projector and camera. In 
addition, the corner radius has been de- 
creased to be in accord with present 
practice of essentially square corners." 

It is obvious that camera and projector 
aperture standards are completely inter- 
dependent and the two should have been 
processed simultaneously. Had this been 
done, the values of E and F in both 
standards would probably have been 
modified by the amount of the shift in the 
camera aperture centerline. On the 
authorization of Henry Hood and Glenn 
Dimmick, Engineering Vice-President and 
Standards Committee Chairman, respec- 
tively, these changes have now been incor- 
porated in both draft revisions. 

It should be noted in this first publication 
of PH22.59, as revised from the earlier 
Z22. 59-1 947, that the values of C, E and 
F have been altered by 6 mils and that the 
title has been slightly modified. The 
value of dimension F, of course, affects the 
space available for the sound record, as 
specified in American Standard Z22.40- 
1950. The possibility of conflict on this 
score should be given consideration in 
your critical review of these standards. 
H.K. 



October 1953 Journal of the SMPJE Vol. 61 



557 



Proposed American Standard 

Aperture for 
35mm Sound Motion -Picture Projectors 

Second Draft 



PH22.58 

Revision of Z22.58-1947 





















n 










n 






E 


~\ 


) 




- 


-F 






L-J 




















A 












O 


1 


1 - 
<T. 


6 


- 








el 




PROJECTOR 












1 




APERTURE ' 


t 










( ) 








R s 


o 








1 


D 


< 
F 


[ 

JLM 







































GUIDED EDGE 



TRAVEL 



PROJECTOR 
"APERTURE 



IMAGE 



Dimension 


Inches 


Millimeters 


A 


0.825 0.002 


20.95 rt 0.05 


B 


0.600 0.002 


15.25 =t 0.05 


C 


0.738 0.002 


18.74 =t 0.05 


D 


0.0155 


0.394 


E 


0.022 


0.56 


F 


0.021 


0.53 


G 


0.049 


1.24 


R 


Not > 0.005 


Not > 0.13 


a = b = V* longitudinal perforation pitch. 



These dimensions and locations are shown relative to unshrunk raw stock. 

Note: The aperture dimensions given result in a screen picture having a height-to-width ratio of 3 to 4 
when the projection angle is 14 degrees. 



NOT APPROVED 



558 



October 1953 Journal of the SMPTE Vol. 61 



Proposed American Standard 

Aperture for 
35mm Sound Motion -Picture Cameras 

First Draft 



PH22.59 

Revision of Z22.59-1947 





a 










a 


GUIDED 




J 


- 


r 




F 


k 


EDGE 




LJ 










o 


TRAVEL 




















( \ 
















\ ; 


E 



> 


G 


* 








, v 




L- 












' ' 




h~ 

PAMPRA 








CAMERA 




o 




APERTURE 




\ 


a 


APERTURE 






1 


) 

\ 


F 


LM 







































Dimension 


Inches 


Millimeters 


A 


0.868 =t 0.002 


22.05 =t 0.05 


B 


0.631 =fc 0.002 


16.03 0.05 


C 


0.738 0.002 


18.75 0.05 


D 


0.117 


2.97 


E 


0.016 


0.38 


F 


0.115 


2.92 


G 


0.049 


1.24 


R 


0.03 Approx. 


0.76 Approx. 


a = b = !/2 longitudinal perforation pitch. 



These dimensions and locations are shown relative to unshrunk raw stock. 

Note: The aperture dimensions given in combination with an 0.600 X 0.825 in. (15.25 X 20.95 mm) 
projector aperture result in a screen picture having a height-to-width ratio of 3 to 4 when the projection angle 
is 14 degrees. 



NOT APPROVED 



October 1953 Journal of the SMPTE Vol. 61 



559 



Engineering Activities 



American Standards on Photographic 
Rolls and Sheets 

Below are listed the numbers and titles 
of recently approved American Standards 
in the field of still photography. These 
may be ordered from the American 
Standards Association, 70 E. 45 St., 
New York 17, N.Y. Additional listings 
of such standards will be published in the 
Journal from time to time, as they are 
made available, as a service to those readers 
who maintain an active interest in still, 
as well as motion-picture, photography. 
"Photographic Paper Rolls," PHI. 11 -1953. 

(Revision of Z38. 1.5-1 943 and Partial 

Revision of Z38. 1.6-1 943) 
"Photographic Paper Sheets," PHI. 12- 

1953. (Revision of Z38. 1.43-1 947 and 

Partial Revision of Z38. 1.6-1943) 



British Standards 

Three British Standards and one draft 
standard have been received at the Society 
Headquarters and are listed below. 

BS 586:1953. Photo-Electric Cells of the 
Emission Type for Sound Film Apparatus. 

BS 1404:1953. Screen Luminance (Bright- 
ness) for the Projection of 3 5 Mm Film. 

BS 1988:1953. Measurement of Frequency 
Variation in Sound Recording and 
Reproduction. 

CR (ACM) 3896. Draft Recommendations 
for Determining and Expressing the Per- 
formance of Loud Speakers by Objective 
Measurements. 

Loan copies of the above are available 
upon request. Henry Kogel, Staff Engineer. 



Book Reviews 



Principles of Color Photography 

By Ralph M. Evans, W. T. Hanson, Jr., 
and W. Lyle Brewer. Published (1953) 
by John Wiley & Sons, 440 Fourth Ave., 
New York 16, N.Y. i-xi + 672 pp. + 
21 pp. bibliography + 15 pp. index. 
324 illus. 6 X 9 in. Price $11.00. 

Some of the best scientific reference 
books have been written by research 
workers who suddenly have become 
engaged in a subject and find that no 
authoritative text exists to give them 
an overall picture of the fundamental 
principles of that subject. In the course 
of reading hundreds of original papers 
and slowly fitting the essential facts and 
concepts together, the thought occurs 
how much easier the task would be if a 
reference work were available, containing 
the necessary background data required 
for investigating the subject further. 

Apparently the authors of this book 
experienced such thoughts, especially Evans 
and Hanson, who recall in the preface 
the need that existed in the early years 
of Kodachrome for an exhaustive treat- 
ment of the actual basis on which processes 



of color photography had been and were 
being developed. In 1938, three years 
following the introduction of 16mm Koda- 
chrome, they began the preparation of 
the present text. World War II and 
increased responsibilities afterwards made 
the completion of the book difficult, and 
so Mr. Brewer was enlisted in 1946. Mr. 
Brewer spent practically full time for 
several years in bringing the book to its 
final state. This gives one an idea of the 
comprehensive nature of the book and a 
fuller understanding of the tremendous 
amount of effort involved in writing a 
book in a field where no similar one 
existed before. 

To a very large extent the book is an 
organized compilation of previously pub- 
lished material. However, much un- 
published original work is included, also. 
There are 18 chapters, with the following 
titles: Response of the Eye to Light in 
Simple Fields; Systems of Color Speci- 
fication and Measurement; Responses 
to Light in Complex Fields; Visual Proc- 
esses and Color Photography; Response 
of Photographic Materials; Color Re- 
sponse of Photographic Materials; Photo- 



560 



graphic Formation of the Color Image; 
Color Photographic Systems; Types of 
Dyes and Other Colorants; Optical 
Characteristics of Colorants in Combina- 
tion; Measurement of Density; Color 
Sensitometry ; Analyses of Color-Sensito- 
metric Characteristics ; Reproduction 
Characteristics of a Hypothetical Sub- 
tractive Color Process ; Duplicating ; Copy- 
ing a Color Photograph; Color Repro- 
duction Theory for Additive Photographic 
Processes ; and Color Reproduction Theory 
for Subtractive Photographic Processes. 
An extensive bibliography, author index 
and subject index complete the book. 

Mathematics is used freely throughout 
the text wherever the subject material is 
amenable to such treatment. The authors 
state that they attempted to word the 
text so that a careful study of the mathe- 
matical steps would not be required for 
an understanding of the principles and 
conclusions reached. Their attempt in 
this has not been too successful, in the 
opinion of the reviewer, but it is probably 
as close to success as could be expected 
without an extensive expansion of the 
present book. Perhaps if the discussions 
on certain subjects which have no place 
in the book had been eliminated, it would 
have been possible to give a fuller develop- 
ment of the mathematical steps. Chapter 
V, for example, on the response of photo- 
graphic materials, which takes over 50 
pages, is certainly out of place, and anyone 
qualified to read the rest of the book will 
ignore it. There are at least another 
200 pages in the book that will be regarded 
as "filler" by the audience for which the 
book is intended. 

Except for the above general criticism, 
the book is extremely well done. It 
presents a thorough analysis of the problems 
involved in color reproduction theory and 
shows to what extent practical processes 
have approached ideal solutions. Color 
sensitometry and color densitometry are 
treated in a very lucid style. Interimage 
effects are nicely described and mathe- 
matically correlated with practice. The 
wealth of experimental data and the 
numerous computations are almost over- 
whelming at times. The chapters, from 
chapter seven through chapter eighteen, 
will be of greatest interest to most ex- 
perienced photographic color technologists. 



These chapters contain the bulk of the 
new material presented in the book, but 
the going gets rough in spots if one's 
knowledge of determinants and matrices 
is rusty. There is no doubt but that this 
book should become a part of every 
technical reference library and should be 
owned personally by every color tech- 
nologist. Lloyd E. Varden, Technical Di- 
rector, Pavelle Color Inc., 533 W. 57 St., 
New York 19, N.Y. 



New Screen Techniques 
Edited by Martin Quigley, Jr. Published 
(1953) by Quigley Publishing Co., 1270 
Sixth Ave., New York 20, N.Y. 208 pp. 
71 illus. 6 X 9 in. $4.50. 

This potpourri of 26 illustrated articles 
is divided into two parts: Part I deals 
with the production and exhibition of 
stereoscopic motion pictures; Part II 
covers similar material in relation to the 
Cinerama and CinemaScope wide-screen 
systems. 

Of the ten stereo articles in Part I, 
four are worthy of note: "Polaroid and 
3-D Films" by William H. Ryan; "Basic 
Principles of 3-D Photography and Pro- 
jection" by John A. Nor ling; "The 
Stereo Window" by Floyd A. Ramsdell;