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THE ORIGINS OF MODERH PHOTOGRAPHY
George H. Dueker
Photography as we know it today Is the work of many
men. It began as a result of experiments of alchemists and
early chemists on the action of light on certain chemicals.
The fact that silver salts blatekened if exposed to light was
known by 1565, but not until 1727 did anyone try to use this
property to form images. In that year J.H. Schulze used a
mixture of silver nitrate and chalk under stencilled letter
to form an image after exposure to light. This and similar
experiments led to the experiments of T. Wedgewood with a
mixture of silver nitrate on the surface of paper and leather
in 1tS02. It was also suggested at about this time that silver
chloride was more sensitive than silver nitrate. These
experiments were only moderately successful because of
the length of the exposure required to form an image, ?nd
the fact that there was at this time no knowm means of
removing the unexposed silver salt so that the Image
could be made permanent.
In these early experiments, the silver salt was usually
exposed directly to the light, or at best, an image was
formed by blocking off part of the sensitized surface by
covering it with a stencil of some sort. Photographic
images were first formed when one of these sensitised
surfaces was exposed to the light in a camera obscura.
The invention of the camera obscura is ' usually credited to
Giovanni Uattista del Porta in 1533) although a number of
other inventors discussed the fact that such a device
could probably be built before this time. D.Barbaro in
1 568 proposed the use of con -ex lenses and a diaphram to
secure a greater sharpness of images. This use of lenses
in cameras greatly reduced the required exposure time.
In his book published in 1 665, J Zahn described a portable
camera obscura with a lens to secure greater brilliancy of
image, and side wings to shield it from extraneous light.
By the beginning of the 1 8 th century, the portable
camera obscura had become a regular article of commerce,
although at this time it was not used by photography.
Toward the end of the 1 8 th century people began
to request that some way of preserving the images they
saw through their camera obscura be devised. Up to this
time, the only simple way of producing pictures was the
silhouette. This consisted of simply tracing the shadow
of whatever the subject of the picture happened to be.
J. ITicephore Mepce first tried photography with silver
chloride in 1817» Unfortunately,' while he could produce
images, they were not permanent. The first successful
photographs were taken in 1822. At this time asphaltum
was used. When it ife exposed to light, it becomes insoluable
in its usual solvents. This was the first permanent photograph,
The process was called heliography. The contrast produced
in these pictures was poor, and the required exposure time was
In 1829 L.J.M. Daguerre discovered that an iodized silver
plate could be exposed to light fo'r a few seconds, and the
image thus formed coulsf be developed if the plate were fumed
with mercury vapor. The image was then fixed with a solution
of thiosulphate of soda and toned by treatment with gold
In 1 839 Fox Talbot announced that he had made permanent
photographs by using silver iodide with an excess of nitrate,
and fixation with with sodium thlosulphate. This produced a
negative image, from which a positive could be produced by
repeating the same process. Talbot's process was the first
stage in the real line of photography, the inventions of
Daguerre and hTiepee being bypaths whose chief importance was
the stimulation they gave to photographic evolution.
In 1851 Scott Archer published his wet collodion
proeess. In this process, a clean glass plate was coated
with iodized colodion, and sensitized by dipping it in a
bath of silver nitrate. The plate was then exposed wet ,
and developed immediately with a solmtion of pyrogallol and
acetic acid, and fixed with sodium thlosulphate. The necessity
for preparing the plated immediately before exposure and
developing them Immediately after considerably limited
the practice of photography, although the process produced
acceptable pictures. This was the process that was used by
the well known photographer of the Civil War, Ma their Brady .
In the 1870's, a great deal of experimental work was
done in an attempt to replace collodion with a gelatine emulsion
to eliminate the need to expose the plates while they were
wet. A number of men working on the problem Independently
finally solved the problem of making dry plates almost
In 188^- George Eastman developed the roll film system of
photography. Originally paper was used as the hacking material,
but it was soon replaced with nitrocellulose film. This film
was applied at once by Thomas -Zdison to making motion
pictures. The highly inflammable nitrocellulose film was
later replaced with cellulose acetate, which is still being
used to- ay.
With the development of roll film, all of the basic
elements of photography as we now know it were in exi stance.
Since this time there has been a constant improvement in the
materials used, but the basic processes are still the same.
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