Shutter (photography)

In photography, a shutter is the part of a camera that opens for a controlled period of time to let light in during taking a picture.
A shutter can also be used to allow pulses of light to pass outwards, as in a movie projector or signal lamp.
Camera shutters.
Camera shutters can be fitted in two positions:
Shutters immediately behind the lens were used in some cameras with limited lens interchangeability. Shutters in front of the lens were used in the early days of photography.