Note that aspect ratio refers here to the projected image, which may be different that the image that was initially recorded. There are various methods of producing a widescreen image of any given proportion. These are listed below in the order of popularity in the shooting of films for presentation in a theater.
1.Masked. The film is shot in the standard ratio, but the top and bottom of the picture are hidden or masked off by mattes in the projector. Alternatively, a hard matte in the camera may be used to mask off those areas while filming. The picture quality is reduced because only glass exporter part of the image is being expanded to full height. Sometimes films are designed to be shown in cinemas in masked widescreen format but the full unmasked frame is used for television.
2.Anamorphic. As used by CinemaScope, Panavision and others, anamorphic camera lenses compress the image horizontally so that it fits a standard frame, and anamorphic projection lenses restore the image and spread it over the wide screen. The picture quality is reduced because the image is stretched to nearly twice the original area, but improvements in film and lenses have made this less noticeable.
3.Super gauges. The full negative frame, including the area traditionally reserved for the sound track, is filmed using a wider gate. The print is then shrunk and/or cropped in order to fit it back onto release prints. The aspect ratio for Super 35, for example, can be set to virtually any projectable standard.
4.Taller pull down. 35mm pull-down, as used for Cinerama, can facilitate better and brighter 3D projection, or offer a low cost means to approach 70mm image brightness and clarity using 35mm film and an anamorphic lens. Commonly referred to as "Cine-160" by recent advocates.
5.Large gauge. A 70mm film frame is not only twice as wide as a standard frame but also has greater height. Shooting and projecting a film in 70mm therefore gives more than twice the image area of non-anamorphic 35mm film with no loss of quality. No major dramatic narrative film has been filmed on this format since 1996 (the last being the Kenneth Branagh version of Hamlet), although big release-films do sometimes strike 70mm "roadshow" prints from 35mm masters. Paramount's VistaVision was a large gauge precursor to 70mm film; it ran standard 35mm film through the camera horizontally to achieve a widescreen effect. VistaVision is still used for shooting special effects, and is notable for its use in Lucasfilm's original three Star Wars films, among others.
6.Multiple cameras/projectors. The Cinerama system originally involved shooting with three synchronized cameras locked together side by side, and projecting the three resulting films on a curved screen with three synchronized projectors. Later Cinerama movies were shot in 70mm anamorphic (see below), and the resultant widescreen image was divided into three by optical printers to produce the final threefold prints. The technical drawbacks of Cinerama are discussed in its own article. Only one feature film, How the West Was Won was shot in "pure," three-camera Cinerama. With the exception of a few films created sporadically for use in specialty Cinerama theaters, the format is essentially dead. A non-Cinerama, three-projector process was famously pioneered for the final reel of Abel Gance's 1927 epic, Napoléon. Consisting of three 1.33 images side by side, the total aspect ratio of the image is 4:1. The technical difficulties in mounting a full screening of the film, however, make most theaters unwilling or unable to show it properly.
7.70mm anamorphic. 70mm with anamorphic lenses creates an even wider high-quality picture. Known as Ultra-Panavision and MGM-65, and most famously used in the 1959 version of Ben-Hur, this system is basically obsolete, although it would likely be technically easy to revive.