Film gate

The film gate is the rectangular opening in the front of a motion picture camera where the film is exposed to light, or the rectangular opening in the front of a film projector allowing a beam of light through when projecting the film.

In a motion picture camera, the film gate holds the film still while it is exposed to light through the aperture formed by the shutter. During this exposure, the film is held in the gate by a pressure plate behind the film, thereby holding it on a uniform plane and at a calibrated distance from the shutter. This is essential if the resulting image is to be in focus over the whole of the frame of film.

The film gate can be seen by removing the lens and rotating the shutter out of the way.