70 mm film

70 mm film (or 65 mm film) is a wide high-resolution film gauge, of superior quality to standard 35 mm motion picture film format. As used in camera, the film is 65 mm wide; for projection 2.5 mm are added along each outer side of the perforations for magnetic strips holding six tracks of surround sound, although more recent 70 mm prints now use digital sound encoding; however, the vast majority of 70 mm prints predate this technology. Each frame is five perforations tall, with an aspect ratio of 2.20.

History

Film formats with a width of 70 mm have existed since the early days of the motion picture industry. The first 70 mm format 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 by 2 inches. 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. Two other formats, Panoramica and 20th Century Fox's Grandeur, began distribution in 1929 and 1930, respectively.

The "Todd-AO" format, introduced in the 1950s, popularized the format for use in feature length films. 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. Often, as in the case of A Space Odyssey (film), 70 mm films were re-released on 35 mm film for a wider distribution after the initial debut of the film.

The advent of small multi-cinema theater venues, as the norm, and availability of digital soundtrack systems for less expensive 35 mm film led to a decline in use of this expensive format in the 1990s. Lawrence of Arabia is a well-known film , widely shown in 70 mm format; the clarity of its picture, and dramatic impact is apparent in theaters, though much less so on VHS or DVD, due to small home screen size.

70 mm also has presented a difficulty in recent years for VHS and DVD releases, as telecine machines capable of high-level scanning have only been available in limited quantities until recently. This has unfortunately sometimes meant that films were transferred to video via their 35 mm blown-down elements instead of the high-quality full-gauge intermediates; luckily, more and more DVD releases are using the original-gauge source elements as of late.

Uses of 70 mm

Special Effects

Sometimes films, like Close Encounters of the Third Kind, will employ 65 mm film stock for special effects sequences because the film quality does not visibly degrade when special effects are added in post production.

IMAX

A horizontal variant of 65 mm/70 mm, with an even bigger picture area, is used for the high-performance IMAX and Omnimax formats which are 15 perfs. x 70 mm. 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, Astrovision more or less exclusively occupying Japanese planetariums.

Recently, Hollywood has released true "blockbusters" in an IMAX blow-up mode. Even 3D films are being shown in the 70 mm IMAX format. 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. With the recent interest in 3D, some of the hundreds of existing 70 mm projectors may be used to show 3D on standard-sized screens in mult-cinemas.

Blow-ups

Starting in the late 1950s and continuing until the mid-1990s, many 35 mm films were converted onto 70 mm prints for premiere showings in large cities or venues which could accompany the format. This practice occurred for two reasons: The larger image area on each frame of 70 mm film allowed for clearer, sharper, and steadier images on screen, and the six magnetic sound tracks available with 70 mm prints were vastly superior to the two-channel stereo sound tracks available on 35 mm prints. After the introduction of digital sound formats (DTS, SDDS, and Dolby Digital), 70 mm lost one of its major advantages over 35 mm film. Additionally, 70 mm film is more expensive to print than 35 mm film. As a result, a significantly lower number of 70 mm prints are struck today.

The use of 65 mm negative film has been drastically reduced in recent years due to its higher cost. Kenneth Branagh's Hamlet was the last film shot entirely on 65 mm stock. Terrence Malick's The New World, the most recent film to use the format, used it sparingly - only in a handful of scenes - because of the high price of 65 mm raw stock and processing.

Technical Specs

Standard 65 mm (5/70)

(Todd-AO, Super Panavision)

spherical lenses
5 perforations per frame
12.8 frame/ft (42 frame/m)
vertical pulldown
24 frames per second
camera aperture: 2.066 by 0.906 in (52.48 by 23.01 mm)
projection aperture: 1.912 by 0.816 in (48.56 by 20.73 mm)
1000 feet (305 m), about 9 minutes at 24 frame/s = 10 pounds (4.54 kg) in can
aspect ratio: 2.2:1

Showscan

Same as Standard 65 mm except

60 frames per second

IMAX (15/70)

spherical lenses
15 perforations per frame
horizontal pulldown, from right to left (viewed from base side)
24 frames per second
camera aperture: 2.772 by 2.072 in (70.41 by 52.63 mm)
projection aperture: at least 0.80 in (20 mm) less than camera aperture on the vertical axis and at least 0.016 in (0.4 mm) less on the horizontal axis
aspect ratio: 1.43:1

Omnimax

Same as IMAX except

special fisheye lenses
lens optically centered 0.37 in (9 mm) above film horizontal center line
projected elliptically on a dome screen, 20 degrees below and 110 degrees 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. Last known OmniVision Theatres to exist in USA are The Alaska Experience Theatre in Anchorage Alaska, built in 1981 and still operating in 2006, and the Hawaii Experience Theatre in Lahaina Hawaii (closed in 2004).

Dynavision (8/70)

fisheye or spherical lenses, depending on if projecting for a dome or not
vertical pulldown
24 or 30 frames per second
camera aperture: 2.080 by 1.480 in (52.83 by 37.59 mm)

Astrovision (10/70)

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 with perforations next to the edges

External links

Movie film formats

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