Film projection speed:

The rate at which film passes through the projector when the film is screened.  Most sound films are standardized and shown at 24 frames per second (fps).  The projection speed for silent 35 mm. film ranges widely, generally from 14 fps to 24 fps.  The variation in the speed of silent films is due to the variable speeds of hand-cranked cameras and projectors.  Projection speed also varies for 65-70 mm. film depending on the process utilized.