Chromogenic film is somewhat different from conven-
tional silver halide film. A chromogenic emulsion
contains dye couplers as well as silver halides.
During development, the presence of silver that has
been exposed to light leads to a proportional
buildup of dyes. The original silver is then bleached
out, leaving the dyes to form the visible image.
Most color materials use chromogenic development
to produce the final color image, as do several
types of black-and-white film.
In Figure 3.8, notice the darker parts of the original
scene: Receive less light, develop less silver density,
and show less detail.42 ABSOLUTE BEGINNER’S GUIDE TODIGITAL PHOTOGRAPHY
You probably are famil-
iar with the C-41 process,
common at all 1-hour photomats
and pharmacies. The C in C-41
means chromogenic.FIGURE 3.8
Each of these
images received
one stop less
light.Eventually those parts of the negative become clear of silver and print as black.
When a highlight area, like the sky, gets too much light, it blocks up with solid silver
density, appears dark in the negative, and prints as white.The Absolute Minimum
This chapter focused on film, which you might not have expected to see in a digital
photography book. However, film can easily become part of your digital work-
stream. If you have any doubts about its lifespan, film will survive the digital
onslaught, just as theater survived radio, cinema survived television, and bookstores
survived Amazon.
Whether you choose digital or film, keep in mind these important points when tak-
ing pictures:
■ The speed of digital and film is measured using an ISO rating.
■ Double the ISO speed and you double the film’s sensitivity.
■ ISO 800 film is recommended for indoor, low-light photography.
■ Slide film has less perceptible grain and is better for scanning.