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.
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History
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.
Fox Grandeur
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.
Todd-AO
Producer Mike Todd had been one of the founders of Cinerama, a wide-screen movie process that was 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 uses a single 70 mm wide film and was introduced with the film Oklahoma! in October 1955. The 70 mm film is perforated at the same pitch (0.187 inch, 4.75mm) as standard 35 mm film. 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 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. The Todd-AO format was originally intended to use a deeply curved Cinerama-type screen but this failed to survive beyond the first few films. However, in the 1960s and 70s, such films as The Sound of Music (which had been filmed in Todd-AO) and Patton (which had been filmed in a copycat process known as Dimension 150) were shown in some Cinerama cinemas, which allowed for deeply curved screens.
Todd-AO adopted a similar multi-channel magnetic sound system to the one developed for Cinemascope 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 five speakers spaced behind the screen, and the sixth is fed to surround speakers around the walls of the auditorium.
Panavision developed their own 65/70mm system that was technically compatible and virtually identical to Todd-AO. Monikered as Super Panavision 70, it used spherical lenses and the same 2.20:1 aspect ratio at 24 frames per second. Panavision also had another 65mm system, (Ultra Panavision 70), which sprang from the MGM Camera 65 system they helped develop for MGM that was used to film Raintree County and Ben-Hur. Both Ultra Panavision 70 and MGM Camera 65 employed an anamorphic lens with a 1.25x squeeze on a 65mm negative (as opposed to 35mm CinemaScope which used a 2x compression, or 8-perf, horizontally filmed 35mm Technirama which used a 1.5x compression). When projected on a 70mm print, a 1.25x anamorphic projection lens was used to decompress the image to an aspect ratio of 2.76:1, one of the widest ever used in commercial cinema.
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Decline
Due to the high cost 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 35mm film for a wider distribution after the initial debut of the film. South Pacific (1958), Lawrence of Arabia (1962), My Fair Lady (1964), and The Sound of Music (1965) are well-known films widely shown in 70 mm format with a general release in 35 mm format.
Blow-ups
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 included such films as Camelot (1967), Oliver! (1968), Cromwell (1970), and Fiddler on the Roof (1971). These enlargements did not have the sharpness and smoothness of 70 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. However, if a 70mm film was shown in a Cinerama theatre, the Cinerama sound system was used. 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 125 70 mm prints made of 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 favour 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 were rarely made.
Current use
In the late 20th century, the usage of 65 mm negative film drastically reduced, in part due to the high cost of 65 mm raw stock and processing. Some of the few films since 1990 shot entirely on 65 mm stock are Kenneth Branagh's Hamlet (1996), Ron Fricke's Baraka (1992), and its sequel Samsara (2011), Paul Thomas Anderson's The Master (2012) and Quentin Tarantino's The Hateful Eight (2015). 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 four movies, The Dark Knight (featured 28 minutes of IMAX footage), Inception, The Dark Knight Rises (over an hour in IMAX) and Interstellar.
Since the 2010s most of the movie theaters across the world have converted to digital projection systems, largely eliminating 70mm film projectors. 70mm has retained a niche market of amateurs and enthusiasts.
Digital 70 mm cameras
There are three types of digital cinema cameras with a 65 mm sensor, the Phantom 65, the Arri Alexa 65 and the forthcoming IMAX 2D Digital Camera. 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.
Home media
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.
Uses of 70 mm
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 1957 film Raintree County and to incredible success in the 1959 film Ben-Hur and the 2015 film The Hateful Eight, which was filmed with the MGM Camera 65 process at an aspect ratio of 2.76:1. 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.
Special effects
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.
IMAX
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 were rare, with Astrovision largely used in Japanese planetariums. In the 2014 movie Interstellar, a significant amount was shot in the IMAX format. Other scenes were shot in either 35 mm or in the standard 'vertical' 5-perf 65 mm format. IMAX introduced a digital projection system in the late 2000s and most IMAX venues have migrated to digital setup.
70 mm 3D early use
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, itself based on a simplified, earlier developed soviet process called 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 1971 re-release of Warner Bros.' House of Wax used the side-by-side StereoVision format and was distributed in both anamorphically squeezed 35 mm and deluxe non-anamorphic 70 mm form. The system was developed by Allan Silliphant and Chris Condon of StereoVision International Inc., which 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.
IMAX 3D
Hollywood has released films shot on 35 mm as IMAX blow-up versions. Many 3D films were 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.
In 2011 IMAX introduced a 3D Digital camera based on two Phantom 65 cores. The camera has been used for documentaries as well as Hollywood films, the first being the 2014 release of Transformers: Age of Extinction.
Technical specifications
- spherical lenses
- 5 perforations/frame
- 42 frames/meter (12.8 frame/ft)
- 34.29 meters/minute (112.5 ft/minute)
- vertical pulldown
- 24 frames/second
- camera aperture: 52.63 by 23.01 mm (2.072 by 0.906 in)
- projection aperture: 48.56 by 22.10 mm (1.912 by 0.870 in)
- 305 m (1000 feet), about 9 minutes at 24 frame/s = 4.5 kg (10 pounds) in can
- aspect ratio: 2.20:1
Same as Standard 65mm except
- projection aperture: 48.59 by 22.05 mm (1.913 by 0.868 in)
- MGM Camera 65 lenses built by Panavision employed a square-shaped, double wedge-prism anamorphic attachment in front of a shperical objective lens. By the time of Mutiny on the Bounty (1962) Panavision had developed a new set of Ultra Panavision 70 lenses that used a high quality cylindrical anamorphic element in front of the objective lens. These new lenses were far superior to the prism anamorphics--they were lighter, transmitted more light and suffered from less spherical and chromatic aberration.
- 1.25x squeeze factor, projected aspect ratio 2.76:1
Showscan
Same as Standard 65 mm except
- 60 frames per second
IMAX (15/70)
- spherical lenses
- 70mm film, 15 perforations per frame
- horizontal rolling loop movement, from right to left (viewed from emulsion side)
- 24 frames per second
- camera aperture: 70.41 mm × 52.63 mm (2.772 in × 2.072 in)
- projection aperture: at least 2 mm (0.079 in) less than camera aperture on the vertical axis and at least 0.41 mm (0.016 in) less on the horizontal axis
- aspect ratio: 1.43:1
- DMR aspect ratio: 1.89:1, 2.39:1
IMAX Dome / OMNIMAX
Same as IMAX except
- fisheye lens
- lens optically centered 9.4 mm (0.37 in) above film horizontal center line
- projected elliptically on a dome screen, 20° below and 110° above perfectly centered viewers
Omnivision Cinema 180
same as standard 65/70 except:
- photographed and projected with special fisheye lenses matched to large 180 degree dome screen
- Theatres upgraded from 70 mm 6track analog sound to DTS digital sound in 1995.
Omnivision started in Sarasota, Florida. Theatres were designed to compete with Omnimax but with much lower startup and operating costs. Most theatres were built in fabric domed structures designed by Siemens Corporation. The last known OmniVision theatres to exist in USA are The Alaska Experience Theatre in Anchorage, Alaska, built in 1981 (closed in 2007, reopened in 2008), and the Hawaii Experience Theatre in Lahaina, Hawaii (closed in 2004). Rainbow's End (Theme Park) in NZ had the only remaining permanent Cinema 180 attraction until May 2015 when it was demolished.
One of the few producers of 70 mm films for Cinema 180 was the German company Cinevision (today AKPservices GmbH, Paderborn).
- fisheye or spherical lenses, depending on if projecting for a dome or not
- vertical pulldown
- 24 or 30 frames per second
- camera aperture: 52.83 by 37.59 mm (2.080 by 1.480 in)
Astrovision (10/90)
- vertical pulldown
- normally printed from an Omnimax negative
- projected onto a dome
- almost exclusively in use only by Japanese planetariums
- the only 70 mm format without sound, hence the only one with perforations next to the edges
Source of the article : Wikipedia
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