SCOPE OF PHOTOGRAPHY
The average person thinks of photography in connection with motion
pictures, snapshots, and perhaps occasional photographs, but these are
only a small part of the total contribution photography makes to the
world.
The field of photography as an avocation comes very close home to all
of us. No matter what may be our hobby, whether swimming, canoeing,
fishing, hiking, or other kindred sports, photography is a natural
ally. It is not only the interest that our friends manifest in our
pictures that justify their making. It is the pleasure we experience in
reviewing the picture record that makes photography so eminently worth
while. As time passes and details fade from memory, the pictures of the
outings so vividly recall the various scenes and incidents that we live
those joyous days over again as often as we wish.
The ever increasing multiplicity of ways in which photography is
used commercially makes possible only a bare mention of some of the
more important. As a _business_ it consists roughly of four types
of work—portrait, commercial, amateur finishing and motion picture
work. Through the application of photography there have been many
definite advances in observational _scientific investigation_.[12]
Photography is made use of in law courts as evidence in the case
of accidents and in deciphering charred records; in dentistry and
medicine it enables the doctor through the X-ray to make a definite
diagnosis and have records for analysis and study. In meteorological
work a study of clouds, storms and floods is made by the aid of the
camera, while the astronomer is able through the cumulative character
of light action to show stars which are so faint because of their
great distance that they are invisible even through the most powerful
telescopes. In war times photography is the leading factor in securing
much valuable information, airplanes equipped with special cameras
being used to locate the enemy’s position, detect camouflage, and
make aerial maps from which firing data is worked out. In efficiency
tests in the big industrial plants motion picture records are made of
the operations both of machines and men to show where excess and loss
can be eliminated so as to speed up production. The engineer and the
contractor can also check up on the work of individuals as well as make
actual records of details and show the progress made from day to day.
[Footnote 12: See _Photography as a Scientific Implement_, published by
D. Van Nostrand Company.]
And then there is the widespread use of pictures in the magazines
and papers both as _illustrations_ and _advertisements_. There is
scarcely an article on the market which is largely advertised that is
not accompanied by a cut of some kind. In this connection it must be
pointed out the close relationship of photography and photo-engraving.
The engraver uses the photographic print to make the cut from which the
magazine and newspaper pictures are printed.
_Color Photography_ is another line in which definite advances are
being made. Pictures in monochrome while quite faithfully translating
color values into shades of black and white and answering all ordinary
requirements, yet are most unsatisfactory for depicting the grandeur of
a mountain view or the sublime beauty of an evening sunset. Innumerable
processes have been brought forward from time to time and many patents
have been granted for photographic color processes. However, no method
has yet been devised for making pictures in color that even remotely
approaches the simplicity of ordinary black and white photography.
The autochrome process as introduced by M. M. Lumière of Lyons, a
screen plate process, is perhaps the simplest adaptation. It consists
of a glass plate coated with a sticky varnish on which is dusted a
mixture of fine starch grains which have been dyed the three primary
colors and mixed together in suitable proportions resulting in a
colorless coating. Over this is applied a coat of water proof varnish
and then a very thin panchromatic emulsion. The exposure is made as
in the case of an ordinary plate except that the glass side is toward
the lens. By this means the exposure is made through the orange-red,
green and blue-violet starch grains which act as filters. The exposed
plate is developed for a definite time or by inspection, by the aid of
a special green safelight. After rinsing it is immersed in a reducing
solution which will dissolve out the finely divided silver forming
the negative image. When this deposit has been removed the starch
grains transmit light like those which came to them in the camera. The
remainder of the silver salts not affected by the primary exposure
and development is now reduced to metallic silver. This development
must take place while the plate is exposed to a strong white light. The
plates when finished must be viewed either as transparencies or on the
screen as lantern slides.
_Color printing processes_ are hardly practical for the average
amateur. Three negatives are made on panchromatic (color sensitive)
plates or films using orange-red, green and blue-violet process
filters. Each negative must be printed in its complementary color. The
colors in which they are printed may be obtained from pigmented papers
such as carbon; or colored inks, paints or other coloring materials may
be used. The three carbon tissues or prints are then transferred to the
same final support being cemented down in correct register. In spite
of all the difficulties attendant on color photography, even motion
pictures in colors are now possible.
There have been other advances which are almost unbelievable. Objects
more than one hundred miles distant, practically invisible because
of the atmospheric haze, have been photographed by suitable color
sensitive films and filters. Pictures are made in the dark by means
of the invisible ultra-violet ray while there are great possibilities
with the infra-red rays and X-rays. With other constant developments in
all phases of photographic work, who can prophesy what the future will
bring forth?