70mm
70 mm film (or 65 mm film) is a wide high-resolution film gauge for still and motion picture photography, with higher resolution than the standard 35 mm motion picture film format. As used in cameras, the film is 65 mm (2.6 in) wide. For projection, the original 65 mm film is printed on 70 mm (2.8 in) film. The additional 5 mm are for 4 magnetic strips holding six tracks of sound. Although later 70 mm prints use digital sound encoding, the vast majority of existing and surviving 70 mm prints predate this technology. Each frame is five perforations tall, with an aspect ratio of 2.20:1. The vast majority of cinemas are unable to handle 70 mm film, and so original 70 mm films are shown using either 35 mm prints in the regular CinemaScope/Panavision aspect ratio of 2.35:1, or, in later years, by means of digital projectors at these venues.
Films formatted with a width of 70 mm have existed since the early days of the motion picture industry. The first 70 mm format film was most likely footage of the Henley Regatta, which was projected in 1896 and 1897, but may have been filmed as early as 1894. It required a specially built projector built by Herman Casler in Canastota, New York and had a ratio similar to full frame, with an aperture of 2.75 inches (70 mm) by 2 inches (51 mm). There were also several film formats of various sizes from 50 to 68 mm which were developed from 1884 onwards, including Cinéorama (not to be confused with the entirely distinct "Cinerama" format), started in 1900 by Raoul Grimoin-Sanson. In 1914 the Italian Filoteo Alberini invented a panoramic film system utilising a 70 mm wide film called Panoramica.
In 1928, Fox Film Corporation started working on a wide film format using 70 mm film which they named Grandeur. This was one of a number of wide-film processes developed by some of the major film studios at about that time. However, due to strong resistance from movie theater owners, who were in the process of equipping their theaters for sound, none of these systems became commercially successful. Fox dropped Grandeur in 1930.
...
Wikipedia