Photographic Emulsions

The essential component of photography is a light-sensitive coating called an emulsion. When this emulsion is spread on one side of a piece of transparent material, we call it film. When an emulsion is applied to a piece of paper, it is used to make photographic prints. Film and prints may appear to be very different, but their emulsions are essentially the same.

PHOTOGRAPHIC EMULSIONS

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FILM PRINTING PAPER

FIGURE 158 Film and paper emulsions.

All photographic emulsions respond to light in a simple way:Wherever the emulsion is exposed to light, a fine layer of metallic silver will be formed after development. The greater the amount of exposure, the more dense the deposit of silver will be.

LIGHT FROM SUBJECT LIGHT FROM ENLARGER

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LOW LOW

NEGATIVE PHOTO PAPER

FIGURE 159 Film and paper densities.

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