65MM Film
70mm film (or 65mm film) is a high-resolution motion picture film format. As used in camera, the film is 65mm wide; for projection 2.5mm are added along each side for magnetic strips holding six tracks of surround sound. Each frame is five perforations tall, with an aspect ratio of 2.21:1.
Todd-AO
2.21:1 aspect ratio (during filming)
2.35:1 aspect ratio (final 35mm print)
With the introduction of "Todd-AO", 65mm/70mm became popular during the 1950s for the wide screen, sharp picture and, most importantly, high quality sound. The advent of low-grain film stocks and availability of digital soundtrack systems for less expensive and more widely projectable 35mm film led to a decline in the use of this expensive format in the 1990s.
SOURCES:
http://encyclopedia.thefreedictionary.com/70_mm_film
http://www.widescreen.org/aspect_ratios.shtml
http://encyclopedia.thefreedictionary.com/70_mm_film