The Academy ratio of 1.375:1 (abbreviated as 1.37:1) is an aspect ratio of a frame of 35 mm film when used with 4-perf pulldown. It was standardized by the Academy of Motion Picture Arts and Sciences as the standard film aspect ratio in 1932, although similar-sized ratios were used as early as 1928.
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Academy format in the context of CinemaScope
CinemaScope is a cinematographic technique which used an anamorphic lens to produce widescreen pictures. Crucially, these could be shown in theatres using existing equipment (and an adapter). CinemaScope pictures were produced from 1953 to 1967, and less often after.
When 20th Century Fox began using CinemaScope this marked the beginning of the modern anamorphic format in 2.55:1, almost twice as wide as the previously common Academy format's 1.37:1 ratio. Although the technology behind the CinemaScope lens system was made obsolete by later developments, primarily advanced by Panavision, CinemaScope's anamorphic format has continued to this day. In film-industry jargon, the shortened form, 'Scope, is still widely used by both filmmakers and projectionists, although today it generally refers to any 2.35:1, 2.39:1, 2.40:1, or 2.55:1 presentation or, sometimes, the use of anamorphic lensing or projection in general. Bausch & Lomb won a 1954 Oscar for its development of the CinemaScope lens.
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