Anamorphic Aspect Ratio
These lenses are used to film in the widescreen 2.35:1 aspect ratio as seen in big budget feature films for theatrical release. The image is squeed horizontally resulting in a "tall, thin" image which fills the whole of the 35mm academy negative. When the film is shown in a cinema, the image is projected through an anamorphic projection lens to revert it to the full widescreen aspect ratio. This has advantages over other widescreen methods such as Super 35 in that it makes full use of all the available negative resulting in a higher resolution picture.