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Aperture
In a lens the aperture is the orifice, usually an adjustable iris, which limits the amount of light passing through a lens. In a projector the aperture is a mask opening that defines the area of the frame projected.
A useful way of controlling the amount of light passing through a lens is to use an iris diaphragm. This usually consists of a number of metal leaves that are overlapped to form a symmetrical opening of approximately circular shape.
In a cinema motion picture projector, the lens is normally kept wide open and the aperture is in the form of a metal ‘plate’ with a cut-out at the same aspect ratio as the format.
The National Film and Sound Archive of Australia acknowledges Australia’s Aboriginal and Torres Strait Islander peoples as the Traditional Custodians of the land on which we work and live and gives respect to their Elders both past and present.