Let's discuss a few technical aspects you might want to consider. Once you
have a visualization of your subject and how you want to present it to your
viewers, you should consider what film to use, what lenses for what effect,
and your lighting. You will have made many of these choices while preparing
your shooting script.
a. Every photographer has experienced the time when he has seen a shot
he wanted, but when he put the camera up to his eye, he found that the
faster shutter speed for the lighting conditions was too slow to hand-hold.
The photographer has to make a choice:
Pass up the shot.
Find a flash or tripod and chance missing the shot.
Change the ISO of the film allowing him to use faster shutter
b. You decide passing up the shot is out of the question. Unless you
carry a flash and some sort of camera support, you choose to change the ISO
of the film. This situation can be avoided or planned for while conducting
your research and preparing the shooting script.
c. You may choose and plan to increase film speed or "push" the film
and process accordingly. "Pushing" film is assigning it a higher ISO.
(1) Keep in mind that once you change the ISO, you must expose the
entire roll at the new ISO to avoid variations in exposure and development.
When you "push" film like this you are simply underexposing and
overdeveloping to produce a printable negative.
(2) Depending upon development, there can be an increase in contrast
and grain and a loss of sharpness. For use in a newspaper where the print
will be screened, a loss of sharpness might not be to worrisome. However,
if you are doing a documentation it might mean a loss of detail. Here is an
example to illustrate apparent film sensitivity increase when you up a film
(a) You are using a film with an ISO of 400 in low light
conditions that indicate an exposure of 1/15 of a second at f/2 (too slow to
hand-hold). If you double the ISO to 800, the film can be exposed at f/2.8
or at 1/30 of a second. You can even go one step further and rate the ISO
to 1600. You