Motion
picture film is identical to still picture film.
It's no coincidence that both formats use 35mm
film, nor is it a coincidence that 110 Instamatic
is exactly 16mm wide, or 2 1/4 still is 65mm
wide - all film is derived as a cookie-cutter
denomination of the massive rolls of 8x10 inch
Kodak stock. This is why there is 8x10, 4x5,
2 1/4, 35mm, 16mm, and 8mm film; the 8x10 rolls
are halved, halved again, and halved again,
and so on, all the way down the product line.
Film
is configured as a narrow strip of transparent
base material that provides a mechanically stable
surface (barely shrinks or stretches) on which,
a photo-sensitive chemical emulsion (in dry,
solid form) is bonded to. Film is usually cut
into lengths from 50 to 2000 feet. One side
of a piece of film is referred to as the emulsion
side, and the other is called the base side.
On one or both edges of the film, sprocket holes
called "perfs" (perforations) form
a continuous series of holes along the entire
length of the film; the toothed sprockets on
the drive wheels of a camera engage the perfs
to advance the film. At the film gate immediately
behind the lens, a claw engages a perf to pull
down the next frame and center it precisely,
at a (relatively) constant and controlled speed.
On typical 16mm film, a frame is located between
every perf. On Academy 35mm film, each frame
has four perfs on each side.
