70 mm Film

film formats

70mm film is a wide high-resolution film gauge, with higher resolution than standard 35mm motion picture film format. As used in camera, the film is 65 mm wide. The additional 5mm are for magnetic strips holding four of the six tracks of sound.

Although more recent 70 mm prints use digital sound encoding, the vast majority of 70 mm prints predate this technology. Each frame is five perforations tall, with an aspect ratio of 2.20:1. The vast majority of film theaters are unable to handle 70mm film, and so original 70mm films are shown with 35mm prints 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 panaromic film system utilising a 70 mm wide film called ‘Panoramica’.

In 1928, Fox Film Corporation started work 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 the brand in 1930.

Producer Mike Todd had been one of the founders of ‘Cinerama,’ a wide-screen movie process that launched in 1952. Cinerama employed three 35 mm film projectors running in synchronism to project a wide (2.6:1) image onto a deeply curved screen. Although the results were impressive the system was expensive, cumbersome and had some serious shortcomings due to the need to match-up three separate projected images. Todd left the company to develop a system of his own which, he hoped, would be as impressive as Cinerama, yet be simpler and cheaper and avoid the problems associated with three-strip projection, in his own words he wanted ‘Cinerama out of one hole.’

In collaboration with the American Optical company Todd developed a system which was to be called ‘Todd-AO.’ This system uses a single 70 mm wide film and was introduced with the film ‘Oklahoma!’ in 1955. With a five-perforation pull-down the Todd-AO system provides a frame dimension of 1.912 inch (48.56mm) by 0.816 inch (20.73mm) giving an aspect ratio of 2.2:1. The original version of the Todd-AO used a frame rate of 30 per second, 25% faster than the 24 frames per second that was (and is) the standard; this was changed after the second film – ‘Around the World in 80 Days’ because of the need to produce (24 frame/sec) 35 mm reduction prints from the Todd-AO 65mm negative. Also originally the Todd-AO format was intended to use a deeply curved Cinerama-type screen which also failed to survive beyond the first few films.

Todd-AO adopted a similar multi-channel magnetic sound system to the one developed for Cinemascope (an anamorphic lens used for shooting wide screen) two years earlier, recorded on ‘stripes’ of magnetic oxide deposited on the film. However Todd-AO has six channels instead of the four of Cinemascope and due to the wider stripes and faster film speed provides superior audio quality. Five of these six channels are fed to 5 speakers spaced behind the screen, the sixth fed to surround speakers around the walls of the auditorium. Other companies, in particular Panavision, developed their own systems which are technically compatible with Todd-AO. Panavision also had a system (‘Ultra-Panavision 70’) which employed an anamorphic lens to stretch the image to 2.76:1, the widest aspect ratio ever used in commercial cinema.

Due to the costs of 70 mm film and the expensive projection system and screen required to use the stock, distribution for films using the stock was limited, although this did not always hurt profits. Most 70 mm films were also re-released on 35 mm film for a wider distribution after the initial debut of the film. ‘Lawrence of Arabia,’ made in 1962, ‘My Fair Lady,’ made in 1964, and ‘The Sound of Music,’ made in 1965, are well-known films widely shown in 70 mm format with a general release in 35 mm format.

During the 1970s use of 65 mm stock for original photography declined markedly. However 70 mm ‘blow-ups’ of films made in 35 mm were sometimes made for prestige showings. These enlargements did not have the sharpness and smoothness of 65 mm origination, but these larger prints allowed for a brighter image on very big screens and were more stable when projected. In addition 70 mm prints also had better sound quality than was possible from 35 mm. However these ‘blow-ups’ rarely used the full six channels of the Todd-AO system and instead used the four-track mixes made for 35 mm prints, the additional half-left and half-right speakers of the Todd-AO layout being fed with a simple mix of the signals intended for the adjacent speakers (known as a ‘spread’) or simply left blank. From 1976 onwards many 70 mm prints used Dolby noise reduction on the magnetic tracks but Dolby disapproved of the ‘spread’ and instead re-allocated the 6 available tracks to provide for left, center, and right screen channels, left and right surround channels, plus a ‘low-frequency enhancement’ channel to give more body to low-frequency bass. This layout came to be known as ‘5.1’ (the ‘point one’ is the low-frequency enhancement channel) and was subsequently adopted for digital sound systems used with 35 mm.

In the 1980s the use of these ‘blow-ups’ increased with large numbers of 70 mm prints being made of some blockbusters of the period such as ‘The Empire Strikes Back’ (1980). However the early 1990s saw the advent of digital sound systems (Dolby Digital, DTS, and SDDS) for 35 mm prints which meant that 35 mm could finally match 70 mm for sound quality but at a far lower cost. Coupled with the rise of the multiplex cinema, which meant that audiences were increasingly seeing films on relatively small screens rather than the giant screens of the old ‘Picture Palaces,’ this meant that the expensive 70 mm format went out of favor again. The DTS digital sound-on-disc system was adapted for use with 70 mm film, thus saving the significant costs of magnetic striping, but this has not been enough to stop the decline, and 70 mm prints are now very rarely made.

In recent years, the use of 65 mm negative film has also been drastically reduced, in part due to the high cost of 65 mm raw stock and processing. The only recent films shot entirely on 65 mm stock are Kenneth Branagh’s ‘Hamlet’ (1996), Ron Fricke’s ‘Baraka’ (1992), and its sequel ‘Samsara’ (2011). Other films used 65 mm cameras sparingly, for selected scenes or special effects. Films with limited 65 mm footage include Terrence Malick’s ‘The New World’ (2005) and Christopher Nolan’s latest three movies, ‘The Dark Knight’ (featured 28 minutes of IMAX footage), ‘Inception,’ and ‘The Dark Knight Rises’ (over an hour in IMAX). ‘Samsara,’ in contrast, is one of only two feature-length film in over a decade to be shot entirely in 65 mm, the other being Paul Thomas Anderson’s ‘The Master.’

For home theater, VHS and DVD did not offer enough resolution to carry the full image quality captured by 70 mm film, and VHS and DVD video transfers were usually prepared from 35 mm reduction elements. The high-definition Blu-ray format, in contrast, can potentially reveal the quality advantage of 70 mm productions. Although telecine machines for 70 mm scanning are uncommon, high-resolution transfers from high-quality full-gauge elements can reveal impressive technical quality. There is currently one type of digital cinema camera with a 65 mm sensor, the Phantom 65. Otti International’s Phil Kroll developed the world’s first 65/70 mm telecine transfer system. This camera has been used in Hollywood to digitally master 70 and 65 mm films.

An anamorphic squeeze combined with 65 mm film allowed for extremely wide aspect ratios to be used while still preserving quality. This was used in the 1959 film ‘Ben-Hur,’ which was filmed with the MGM Camera 65 process at an aspect ratio of 2.76:1, one of the widest prints ever made. It required the use of a 1.25x anamorphic lens to horizontally compress the image, and a corresponding lens on the projector to uncompress it.

Limited use of 65 mm film was revived in the late 1970s for some of the visual effects sequences in films like ‘Close Encounters of the Third Kind,’ mainly because the larger negative did a better job than 35 mm negative of minimizing visible film grain during optical compositing. Since the 1990s, a handful of films (such as ‘Spider-Man 2’) have used it for this purpose, but the usage of digital intermediate for compositing has largely negated these issues. Digital intermediate offers other benefits such as lower cost and a greater range of available lenses and accessories to ensure a consistent look to the footage.

A horizontal variant of 70 mm, with an even bigger picture area, is used for the high-performance IMAX format which uses a frame that is 15 perforations wide on 70 mm film. The Dynavision and Astrovision systems each use slightly less film per frame and vertical pulldown to save print costs while being able to project onto an IMAX screen. Both are rare, with Astrovision largely used in Japanese planetariums.

The first commercial introduction of 70 mm single projector 3D was the 1967 release of ‘Con la muerte a la espalda,’ a Spanish/French/Italian co-production which used a process called Hi-Fi Stereo 70. This process captured two anamorphic images, one for each eye, side by side on 65 mm film. A special lens on a 70 mm projector added polarization and merged the two images on the screen. The 1975 re-release of Warner Bros.’ ‘House of Wax,’ used a similar process without anamorphics called Stereovision. This format was developed by Allan Silliphant and Chris Condon, of Stereovision International Inc., who handled all technical and marketing aspects on a five-year special-royalty basis with Warner Bros. The big screen 3D image was both bright and clear, with all the former sync and brightness problems of traditional dual 35 mm 3D eliminated. Still, it took many years more before IMAX began to test the water for big-screen 3D, and sold the concept to Hollywood executives. Recently, Hollywood has released films shot in 35 mm as IMAX blow-up versions. Now many 3D films are being shown in the 70 mm IMAX format. ‘The Polar Express’ in IMAX 3D 70 mm earned 14 times as much, per screen, as the simultaneous 2D 35 mm release of that film in the fall of 2004.

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