UCLA Film and Television Archive’s Randy Yantek holds a strip of 35mm film in the “Fox Print” format used for projection of the wide-screen anamorphic “CinemaScope” format introduced by 20th Century Fox film studio in 1953. ”
Note the narrower than normal perforations to allow the additional magnetic sound tracks. These came to be called “Fox Holes” or “CS”(CinemaScope) perforations
Background from online sources:
Fox had initially intended to use 3 channel stereo from magnetic film for CinemaScope.
Although CinemaScope was capable of producing a 2.66:1 image, the addition of magnetic sound tracks for multi-channel sound reduced this to 2.55:1.
However, Hazard E. Reeves‘ sound company had devised a method of coating 35mm stock with magnetic stripes and designed a 3 channel (left, center, right) system based on three .063″ (1.6mm) wide stripes, one on each edge of the film outside the perforations, and one between the picture and the perforations in approximately the position of a standard optical soundtrack. Later it was found possible to add a narrower .029″ (0.74mm) stripe between the picture and perforations on the other side of the film; this fourth track was used for a surround channel, also sometimes known at the time as an “effects” channel. In order to avoid hiss on the surround/effects channel from distracting the audience the surround speakers were switched on by a 12 kHz tone recorded on the surround track only while wanted surround program material was present.
This 4-track magnetic sound system was also used for some non-CinemaScope films; for example Fantasia was re-released in 1956, 1963, and 1969 with the original Fantasound track transferred to 4-track magnetic.
Format Specifications on Widescreen Museum.com:
Article from March, 1953 American Cinematographer Magazine:
Boardwell is the Jacques Ledoux Professor of Film Studies at the Univ. of Wisconsin, Madison Department of Communication Arts.
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