Shutter
In photography, a shutter is a device that administers the exposure by admitting light to the film for a specific period of time. Shutters are normally of two basic types: A timing mechanism is required to support the different shutter speeds. These were originally pure mechanical devices, but are now mostly replaced by electronic timers.In cinematography projection, the shutter admits light from the image to the projection screen. To avoid flicker, the same image is projected 2 times for 24 fps film, and 3 times for 18 fps amateur film.
See also: shutter speed, camera, photographic lens
