Refers to the dimensions of the apertures used in motion picture cameras to expose cinematograph film and in projectors for its presentation on the screen of the cinema theatre. They have been internationally standardized for all gauges of film now in commercial use.
It is general practice for the camera aperture to be slightly larger all round than the mask used in the projector, so as to avoid the image of an unexposed area of negative being projected, but camera masks or reduced apertures smaller than the projector aperture height are sometimes used in photography of wide screen formats. The printed area on the positive and release print is always made larger than the projector aperture and usually corresponds at least to the area exposed on the camera negative.
The generally accepted dimensions for camera and projector apertures for various gauges of film and formats of presentation are shown in the following table.
camera (AR 1.33:1)
projector (AR 1.33:1)
camera (AR 1.37:1)
projector (AR 1.37:1)
|35mm||Wide screen projector (AR 1.66:1)||0.825||0.497||20.96||12.62|
|35mm||Wide screen projector (AR 1.75:1)||0.825||0.472||20.96||11.99|
|35mm||Wide screen projector (AR 1.85:1)||0.825||0.446||20.96||11.33|
(Techniscope, Ultra semi-scope, etc)
projector (AR 2.35:1)
Note: AR = Aspect ratio