Black and White Photography

3 Black-and-White Film


There are many different types of film available and different reasons to use
each type. Sometimes your choice of film is a practical matter; for instance, you
may need a film sensitive enough to make a picture in low light. Other times
your choice will be aesthetically driven; perhaps you need a film that reproduces
all the subject’s textures and tones as smoothly as possible. Whatever
your choice, it’s highly likely that the film you use will have a noticeable effect
on the way the picture ultimately looks.
Black-and-white films consist of a clear, flexible, plastic support, called the
base, coated with a microscopically thin emulsion. The emulsion is a chemical
compound of light-sensitive silver halide crystals suspended in gelatin. It is coated
with a protective layer to minimize scratching (and other physical damage caused
by handling) and backed by an antihalation layer that helps promote image
sharpness.
Different films often have strikingly distinctive characteristics, but sometimes
the variations are quite subtle. These are the most important characteristics of
black-and-white films:
film speed
grain
tones
contrast
Film speed. Film speed is a measurement of how sensitive a film is to light. A
film that is highly sensitive to light is called a fast film, or just “fast”; a film with
low sensitivity is a slow film, or just “slow.”
The most common way to quantify film speed is according to its ISO (International
Standards Organization) rating. A film with a higher ISO number
needs less light to properly capture an image than a film with a lower ISO
number. For example, ISO 400 film is more sensitive to light than ISO 100; it
will take four times more light to properly expose ISO 100 film as it will take
to properly expose ISO 400 film (400 ÷ 100