An Introduction to Film

FILM, VIDEO, AND DIGITAL TECHNOLOGIES: AN OVERVIEW 487

The motion-picture camera moves unexposed film from
one storage area, called the feed spool(or, in profes-
sional cameras today, the portion of the magazine that
stores unexposed film), along the sprocketed rollers,
which control the speed of the film as it moves through
the camera and toward the lens, which focuses the
image on the film as it is exposed. The aperture(or gate)
is essentially the window through which each frame of
film is exposed. The shutter—a mechanism that shields

the film from light while each frame is moved into

place—is synchronized with the motion of the pull-

down claw, a mechanism used in both cameras and

projectors to advance the film frame by frame. The pull-

down claw holds each frame still for the fraction of a

second that the shutter allows the aperture to be open

so that the film can be exposed. The take-up spool(or,

again, the portion of the magazine that stores exposed

film) winds the film after it has been exposed.

FIGURE 11.1 The Motion-Picture Camera

Aperture

(gate)

Aperture

plate

Pressure

plate

Keepers

Film

Feed spool

Shutter

Pull-down claw Take-up spool

Sprocketed

rollers