Cinemascope, or more strictly CinemaScope, was a widescreen movie format used in the US from 1953 to 1967. Using anamorphic lenses and 35 mm film it could project film at a 2.66:1 ratio, twice as wide as conventional lenses could achieve.
It was developed by 20th Century Fox to supplant the complex, multi-projector Cinerama process, first shown in 1952. The actual anamorphic process, initially called Anamorphoscope, was developed by Henri Chétien around 1927 using lenses he called hypergonar. Chétien had been attempting to sell his process to Hollywood since the 1930s but with little interest, until the advent of Cinerama. Another factor was the rise of television, which meant that the studios saw the need for a spectacle to compete.
The hypergonar lens patents were acquired by 20th Century Fox in 1952 and the system was renamed Fox CinemaScope. The advantage over Cinerama was that all the system needed was an additional lens unit fitted to the front of ordinary cameras and projectors, although stereo sound could be carried on separate 35mm tracks. It was first demonstrated in 1953 and the first film shot was The Robe (September 1953). The technology was licensed by Fox to MGM and Disney and shortly afterwards to Columbia, Universal and Warner. However, initial uncertainty meant that a number of films were shot simultaneously with anamorphic and regular lenses. Also only the 'biggest' films were made in Cinemascope, around a third of the total produced.
Although Cinemascope was capable of producing a 2.66:1 image, the addition of stereo information could reduce this to 2.55:1. A change in the base 35 mm film aperture eventually reduced Cinemascope to 2.35:1. Often cinemas with smaller screens would further crop the format to make it fit. A general problem with expanding the visible image meant that there could be visible grainyness and brightness problems, so to combat this larger formats were developed; initially an unsuccessful 55 mm, and later 65 and 70 mm.
Since the actual anamorphic process was not patentable (it had been known for centuries and had been used in paintings such as "The Ambassadors" by Hans Holbein), some studios sought to develop their own systems rather than pay Fox - RKO used Superscope, Republic used Naturama, Warner developed Warnerscope. Other systems developed included Panatar, Vistarama, Technovision and Euroscope. Cinemascope itself was called Regalscope when used by the Fox adjunct Regal Films for black-and-white features.
Many US studios adopted the cheaper, non-Fox, but still anamorphic Panavision system and by the mid-1960s even Fox had abandoned Cinemascope for Panavision. The initial problems with grain and contrast were eventually solved thanks to improvements in film stock and lenses.