35 mm film

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This article is primarily about the use of 35mm film in movies. For more detailed information on its use in still photography, see 135 film.

Image:35mm.jpg

35 mm film is the basic film format most commonly used for both still photography and motion pictures, and remains relatively unchanged since its introduction in 1889 by Thomas Edison. The photographic film is cut into strips 1 3/8 inches wide, with six perforations per inch along both edges. The format was initially called Edison size. The flattened perforations were introduced by Bell & Howell around 1900, which remain to this day for original camera negative film. Kodak-Standard perforations were introduced some ten years later for projection use.

A variation developed by the Lumière Brothers used a single circular perforation in the centre of the film between frames.

The film format was introduced into still photography as early as 1913 (the Tourist Multiple) but first became popular with the launch of the Leica camera, created by Oskar Barnack. In normal still photography use, the film, with Kodak Standard perforations, is used horizontally, with each frame having an aspect ratio of 2:3, a size of 24 x 36 mm. See the 135 film section.

In the conventional motion picture format, frames are four perforations tall, with an aspect ratio of about 1.37. Still cameras in 35 mm and the VistaVision motion picture format use a horizontal frame with is eight perforations wide, resulting in a wider aspect ratio of 3:2 and greater detail, as more of the negative area is used per frame.

The commonly used anamorphic widescreen format uses a similar four-perf frame, but an anamorphic lens is used on both the camera and projector to produce a wider image, today with an aspect ratio of about 2.39 (but formerly 2.35 until 1970). The image as stored on the film print appears horizontally compressed.

Most films today are shot and projected using the 4-perforation format, but cropping the top and bottom of the frames for a medium aspect ratio of 1.85 or 1.67. In television production, where compatibility with an installed base of 35 mm film projectors is unnecessary, a 3-perf format is commonly used, giving the 16:9 ratio used by HDTV and reducing film usage by 25%. 3-perf is also commonly used with Super 35 mm film cameras which require an intermediate step either way and is increasingly being adopted as digital intermediate supplants optical resizing for making an intermediate print.

When sound was introduced to the cinema, after some initial attempts at using synchronized record cylinders, etc., the sound started to be stored optically directly on the film. This analog soundtrack takes up a small strip to the left of the picture area. The film picture size of silent movies was 1 inch by .75 inches giving an aspect ratio of 4:3 or 1.33:1. In 1928, the width and height of the picture were reduced to give an aspect ratio of 1.37:1 (known as standard or Academy ratio) by the Academy of Motion Picture Arts and Sciences. After the introduction of the first anamorphic process (Cinemascope in 1953), non-anamorphic films became wider by matting out a portion of the Academy frame. The flat (non-anamorphic) aspect ratio is presently 1.85:1 in most countries, though some European nations prefer the 1.66:1 ratio.

New digital soundtracks introduced since the 1990s include Dolby Digital, which is stored in between the perforations; SDDS, stored in two strips along the outside edges (beyond the perforations), and DTS, where sound data is stored on a separate compact disc synchronized by a timecode track stored on the film just to the right of the analog soundtrack and left of the frame. Because all these soundtrack systems appear on different parts of the film, one movie can contain all of them and be played in the widest possible number of theaters regardless of which sound systems are or are not installed. The optical track technology has changed too; currently all distributors and theaters are in the process of phasing over to cyan-dye optical soundtracks instead of black and white ones (which are less environmentally friendly). This requires installation of a red laser or LED photo-sensor, which is backwards-compatible with older tracks. (The cyan tracks can't be read with older photo-sensors.) Anything Else was the first film only to be released with cyan tracks. The transition is expected to be completed sometime around 2007 and has already happened in most multiplexes.

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Technical specifications

Image:35mmareas.gif Technical specifications for 35 mm film are standardized by SMPTE.

16 frames per foot (19 mm per frame)
1000 feet = about 11 minutes at 24 frame/s
vertical pulldown
4 perforations per frame (except if using 3-perf for origination)

35 mm spherical

1.37 aspect ratio on camera negative; 1.85 and 1.66 are hard or soft matted over this
camera aperture: 0.866 by 0.630 in (22 by 16 mm)
projector aperture (full 1.37): 0.825 by 0.602 in (21 by 15 mm)
projector aperture (1.66): 0.825 by 0.497 in (21 by 13 mm)
projector aperture (1.85): 0.825 by 0.446 in (21 by 11 mm)
TV station aperture: 0.816 by 0.612 in (21 by 16 mm)
TV transmission: 0.792 by 0.594 in (20 by 15 mm)
TV safe action: 0.713 by 0.535 in (18 by 14 mm); corner radii: 0.143 in (3.6 mm)
TV safe titles: 0.630 by 0.475 in (16 by 12 mm); corner radii: 0.125 in (3.2 mm)