CinemaScope 55

CinemaScope 55 was a large-format version of CinemaScope introduced by Twentieth Century Fox in 1955, which used a film width of 55.625 mm.

Fox had introduced the original 35 mm version of CinemaScope in 1953 and it had proved to be commercially successful. But the additional image enlargement needed to fill the new wider screens, which had been installed in theatres for CinemaScope, resulted in visible film grain. A larger film was used to reduce the need for such enlargement. CinemaScope 55 was developed to satisfy this need and was one of three "high definition" film systems introduced in the mid-1950s, the other two being Paramount's VistaVision and the Todd-AO 70 mm film system.

Fox determined that a system that produced a frame area approximately 4 times that of the 35mm CinemaScope frame would be the optimal trade-off between performance and cost, and it chose the 55.625 mm film width as satisfying that. Camera negative film had larger grain than the film stocks used for prints, so there was a consistent approach in using a larger frame on the film negative than on prints. Since prints need to allow space for soundtracks while camera negative does not, CinemaScope 55 had different frame dimensions for camera negative and print film.

The negative film had the perforations (of the CS "Fox-hole" type) close to the edge of the film and the camera aperture was 1.824" by 1.430" (approx. 46 mm x 36 mm), giving an image area of 2.61 sq. inch. This compares to the 0.866" by 0.732" (approx. 22 mm x 18.6 mm) frame of a modern anamorphic 35 mm negative, which provides a frame area of 0.64 sq. inch. On the print film, however, there was a smaller frame size of approximately 1.34" x 1.06" (34 mm x 27 mm) to allow space for the 6 magnetic soundtracks. Four of these soundtracks (two each side) were outside the perforations, which were further from the edges of the print film than in the negative film; the other two soundtracks were between the perforations and the image. The pull-down for the negative was 8 perforations, while for the smaller frame on the print film, it was 6 perforations. In both cases, however, the frame had an aspect ratio of 1.275:1, which when expanded by a 2:1 anamorphic lens resulted in an image of 2.55:1.

A pre-war camera originally built for the obsolete Fox "Grandeur" 70 mm format was modified to work with the new 55 mm film. Bausch & Lomb, the firm that created the original anamorphic CinemaScope lenses, was contracted by Fox to build new "Super CinemaScope" lenses that could cover the larger film frame.

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