35 mm movie film

35 mm film is a film gauge used in filmmaking, and the film standard. In motion pictures that record on film, 35 mm is the most commonly used gauge. The name of the gauge is not a direct measurement, and refers to the nominal width of the 35 mm format photographic film, which consists of strips wide. The standard image exposure length on 35 mm for movies is four perforations per frame along both edges, which results in 16 frames per foot of film.
A variety of largely proprietary gauges were devised for the numerous camera and projection systems being developed independently in the late 19th and early 20th centuries, along with various film feeding systems. This resulted in cameras, projectors, and other equipment having to be calibrated to each gauge. The 35 mm width, originally specified as inches, was introduced around 1890 by William Kennedy Dickson and Thomas Edison, using film stock supplied by George Eastman. Film 35 mm wide with four perforations per frame became accepted as the international standard gauge in 1909, and remained by far the dominant film gauge for image origination and projection until the advent of digital photography and cinematography.
The gauge has been versatile in application. It has been modified to include sound, redesigned to create a safer film base, formulated to capture color, has accommodated a bevy of widescreen formats, and has incorporated digital sound data into nearly all of its non-frame areas. Eastman Kodak, Fujifilm and Agfa-Gevaert are some companies that offered 35 mm films. As of 2015, Kodak is the last remaining manufacturer of motion picture film.
The ubiquity of 35 mm movie projectors in commercial movie theaters made 35 mm the only motion picture format that could be played in almost any cinema in the world, until digital projection largely superseded it.

History and development

Early history

In 1880, George Eastman began to manufacture gelatin dry photographic plates in Rochester, New York. Along with W. H. Walker, Eastman invented a holder for a roll of picture-carrying gelatin layer-coated paper. Hannibal Goodwin then invented a nitrocellulose film base in 1887, the first transparent, flexible film. Eastman also produced these components, and his was the first major company to mass-produce such film when, in 1889, Eastman realized that the dry-gelatino-bromide emulsion could be coated onto this clear base, eliminating the paper.
With the advent of flexible film, Thomas Edison quickly set out on his invention, the Kinetoscope, which was first shown at the Brooklyn Institute of Arts and Sciences on May 9, 1893. The Kinetoscope was a film loop system intended for one-person viewing. Edison, along with assistant William Kennedy Dickson, followed that up with the Kinetophone, which combined the Kinetoscope with Edison's cylinder phonograph. Beginning in March 1892, Eastman and then, from April 1893 into 1896, New York's supplied Edison with film stock. Dickson is credited as the inventor of 35 mm movie film in 1889,⁶⁵² when the Edison company was using Eastman film.^653–654 The company still received film from Blair after this; at first Blair would supply only film stock that would be trimmed and perforated at the Edison lab to create gauge filmstrips, then at some point in 1894 or 1895, Blair began sending stock to Edison that was cut exactly to specification. Edison's aperture defined a single frame of film at four perforations high.
Around 1896, a 35 mm projector known as a "photo-rotoscope" was made by W. C. Hughes in London, which advanced the film by means of a "dog" motion.
For a time, it had been generally assumed that Dickson was following cinematography formats established by Eastman in producing the film, but Eastman had produced film in sheets that were then cut to order.^652–653 Dickson used the film supplied for Eastman Kodak cameras in 1889, a transparent 70 mm celluloid film, in his development of a more suitable film stock, and "simply slit this film in half";^653–654 it was initially developed for the Kinetoscope, a one-person viewer, not to be projected.⁶⁵⁸ The image was still of high quality, even when magnified, and was more economical than 70 mm film.⁶⁵⁴ 35 mm was immediately accepted as standard by the Lumière brothers, and became the main film used in the UK because it was the stock sold to these filmmakers by the Blair company.⁶⁵³
Edison claimed exclusive patent rights to the design of 35 mm motion picture film, with four sprocket holes per frame, forcing his only major filmmaking competitor, American Mutoscope & Biograph, to use a 68 mm film that used friction feed, not sprocket holes, to move the film through the camera. A court judgment in March 1902 invalidated Edison's claim, allowing any producer or distributor to use the Edison 35 mm film design without license. Filmmakers were already doing so in Britain and Europe, where Edison did not file patents. At the time, film stock was usually supplied unperforated and punched by the filmmaker to their standards with perforation equipment. A variation developed by the Lumière brothers used a single circular perforation on each side of the frame towards the middle of the horizontal axis.

Becoming the standard

When films began to be projected, several projection devices were unsuccessful and fell into obscurity because of technical failure, lack of business acumen on the part of their promoters, or both. The Vitascope, the first projection device to use 35 mm, was technologically superior and compatible with the many motion pictures produced on 35 mm film. Edison bought the device in 1895–96; the Lumiere's 35 mm projection Cinematograph also premiered in 1895, and they established 35 mm as the standard for exhibition.⁶⁵⁸
Standardization in recording came from monopolization of the business by Eastman and Edison, and because of Edison's typical business model involving the patent system: Eastman and Edison managed their film patents well⁶⁵⁶ – Edison filed the 35 mm patent in 1896, the year after Dickson left his employ⁶⁵⁷ – and so controlled the use and development of film.⁶⁵⁶ Dickson left the Edison company in 1895, going on to help competitors produce cameras and other film gauges that would not infringe on Edison's patents. However, by 1900, filmmakers found it too expensive to develop and use other gauges, and went back to using the cheap and widely-available 35 mm.⁶⁵⁷
Dickson said in 1933:
Until 1953, the 35 mm film was seen as "basic technology" in the film industry, rather than optional, despite other gauges being available.⁶⁵²
In 1908, Edison formed "a cartel of production companies", a trust called the Motion Picture Patents Company, pooling patents for collective use in the industry and positioning Edison's own technology as the standard to be licensed out.⁶⁵⁶ 35 mm became the "official" standard of the newly formed MPPC, which agreed in 1909 to what would become the standard: 35 mm gauge, with Edison perforations and a 1.3:1 aspect ratio.⁶⁵² Scholar Paul C. Spehr describes the importance of these developments:
When the MPPC adopted the 35 mm format, Bell & Howell produced cameras, projectors, and perforators for the medium of an "exceptionally high quality", further cementing it as the standard.⁶⁵⁹ Edison and Eastman's form of business manipulation was ruled unlawful in 1914, but by this time the technology had become the established standard.⁶⁵⁷ In 1917, the new Society of Motion Picture Engineers "acknowledged the de facto status of 35 mm as the industry's dominant film gauge, adopting it as an engineering standard".⁶⁵⁹

Innovations in sound

When film editing was done by physically cutting the film, editing the picture could only have been done on the frame line. However, the sound was stored for the whole frame between each of the four sprocket holes, and so the sound editors could cut on any arbitrary set of holes, and thus get -frame edit resolution. With this technique, an audio edit could be accurate to within 10.41 ms."^1–2 A limitation of analog optical recording was the audio frequency would cut off, in a well-maintained theater, at around 12kHz.⁴ Studios would often record audio on the transparent film strips, but with magnetic tape on one edge; recording audio on full 35 mm magnetic tape was more expensive.⁵
Three different digital soundtrack systems for 35 mm cinema release prints were introduced during the 1990s. They are: Dolby Digital, which is stored between the perforations on the sound side; SDDS, stored in two redundant strips along the outside edges ; and DTS, in which sound data is stored on separate compact discs synchronized by a timecode track on the film just to the right of the analog soundtrack and left of the frame. Because these soundtrack systems appear on different parts of the film, one movie can contain all of them, allowing broad distribution without regard for the sound system installed at individual theatres.
The analogue optical track technology has also changed: in the early years of the 21st century, distributors changed to using cyan dye optical soundtracks instead of applicated tracks, which use environmentally unfriendly chemicals to retain a silver soundtrack. Because traditional incandescent exciter lamps produce copious amounts of infrared light, and cyan tracks do not absorb infrared light, this change has required theaters to replace the incandescent exciter lamp with a complementary colored red LED or laser. These LED or laser exciters are backwards-compatible with older tracks. The film Anything Else was the first to be released with only cyan tracks.
To facilitate this changeover, intermediate prints known as "high magenta" prints were distributed. These prints used a silver plus dye soundtrack that were printed into the magenta dye layer. The advantage gained was an optical soundtrack, with low levels of sibilant distortion, on both types of sound heads.