Optical lenses that differently magnify the horizontal and vertical axes of an image. In cinema, the term refers to the lens that compresses the width of a film's frame, and to the lens of the projector, so that when it is projected onto the screen, its normal width returns. The height in both lenses is left undistorted and the result is the wide-screen image. The aspect ratio was at first 2:55:1 and later 2.35:1 to adjust for the optical soundtrack.
