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How does a motion-picture camera move film between individual exposures?

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Diagram showing the negative-positive photographic process: a scene is captured on film in a camera, developed into a negative, projected onto paper with an enlarger, and developed again to produce a positive print. — technology of photography Figure 1: Sequence of negative–positive process, from the photographing of the original scene to enlarged print (see text).

A motion-picture camera moves film between individual exposures using a motor-driven transport system that relies on the film's regularly spaced perforations, or sprocket holes.1

The process functions through the following mechanical steps:

Feeding: Sprocket-driven gears grip the film's perforations to feed it from a dark chamber, known as the forward magazine, into the exposure chamber.1
Positioning: A mechanical claw—often a "dual-fork" mechanism—protrudes to engage the sprocket holes and pulls the film into position behind the shutter.12
Exposure: The film is locked momentarily in place while the shutter opens to expose a single frame. During this time, the film remains motionless.1
Advancement: Once the exposure is complete, the shutter closes to block light, and the claw performs an automatic pulldown movement to advance the film for the next frame.12

Some cameras also utilize pin-registering mechanisms to hold the film with additional firmness within the exposure gate. This cycle is synchronized with a rotary shutter, which ensures light is blocked while the film is in transit and allowed through only when the frame is stationary.21