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35mm 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.
35 mm film frames. At far left and far right, outside the perforations, is the SDDS soundtrack as an image of a digital signal. Between the perforations is the Dolby Digital soundtrack (note the tiny Dolby "Double D" logo in the center of each area between the perforations). Just inside the perforations, on the left side of the image, is the analog optical soundtrack, encoded using Dolby SR to simulate four tracks. The optical timecode used to synchronize a DTS soundtrack, which sits between the optical soundtrack and the image, is not pictured. Finally, the image here is an anamorphic image used to create a 2.40:1 aspect ratio when projected through an anamorphic lens. Note the thin frame lines of anamorphic prints.
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35 mm film frames. At far left and far right, outside the perforations, is the SDDS soundtrack as an image of a digital signal. Between the perforations is the Dolby Digital soundtrack (note the tiny Dolby "Double D" logo in the center of each area between the perforations). Just inside the perforations, on the left side of the image, is the analog optical soundtrack, encoded using Dolby SR to simulate four tracks. The optical timecode used to synchronize a DTS soundtrack, which sits between the optical soundtrack and the image, is not pictured. Finally, the image here is an anamorphic image used to create a 2.40:1 aspect ratio when projected through an anamorphic lens. Note the thin frame lines of anamorphic prints.

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 1892 by William Dickson and Thomas Edison, using film stock supplied by George Eastman. The photographic film is cut into strips 1 3/8 inches or 35mm wide - hence the name. There are six perforations per inch along both edges.

Contents

History of 35 mm film

In 1880 George Eastman started 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's invention of nitrocellulose film base in 1887 was the first transparent, flexible film<ref>The Wizard of Photography: The Story of George Eastman and How He Transformed Photography Timeline PBS American Experience Online. Retrieved July 5, 2006.</ref>; the following year, Emile Reynaud developed the first perforated film stock. Eastman was the first major company, however, to put these components into mass production, when in 1889 Eastman realized that the dry-gelatino-bromide emulsion could be coated onto this clear base and eliminate the paper.<ref>Mees, C. E. Kenneth (1961). From Dry Plates to Ektachrome Film: A Story of Photographic Research. Ziff-Davis Publishing. pp. 15-16.</ref>

With the advent of flexible film, Thomas Alva Edison quickly set out on his invention, the Kinetoscope, which was first shown at the Chicago World's Fair in 1893. The Kinetoscope was a film loop system intended for one-person viewing.<ref name="hone">Kodak Motion Picture Film (H1) (4th ed). Eastman Kodak Company. ISBN 0-87985-477-4</ref> Edison, along with assistant W. K. L. Dickson, followed that up with the Kinetophonograph, which was capable of showing film in rough synchronization with a phonograph record. For both inventions, Eastman manufactured film to Edison's specifications at 35 mm wide. Edison's aperture defined a single frame of film at 4 perforations high.<ref name="katz">Katz, Ephraim. (1994). The Film Encyclopedia (2nd ed.). HarperCollins Publishers. ISBN 0-06-273089-4.</ref>

Edison claimed exclusive patent rights to his 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 had failed to file patents.<ref>Template:Cite book</ref>

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.<ref name="lumiere">Lobban, Grant. "Film Gauges and Soundtracks", BKSTS wall chart (sample frame provided). [Year unknown]</ref> It was Edison's format, however, that became first the defacto standard, and then in 1909 the "official" standard of the newly formed Motion Picture Patents Company, a trust established by Edison.

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 1925. <ref>Scheerer, Theo M. (1960). The Leica and the Leica System (3rd ed). Umschau Verlag Frankfurt Am Main. pp. 7-8.</ref>

Originally film was a strip of cellulose nitrate coated with black-and-white photographic emulsion.<ref name="hone" /> Early film pioneers, like D. W. Griffith color tinted or toned portions of their movies for dramatic impact, and by 1920, 80 to 90 percent of all films were tinted.<ref>Template:Cite book</ref> The first successful natural color process was Britain's Kinemacolor (1908-1914), a two-color additive process that used a rotating disk with red and green filters in front of the camera lens and the projector lens.<ref>Template:Cite book</ref> <ref>Hart, Martin. (1998) "Kinemacolor: The First Successful Color System" Widescreen Museum. Retrieved July 8, 2006</ref> But any process that photographed and projected the colors sequentially was subject to color "fringing" around moving objects, and a general color flickering.<ref>Hart, Martin (May 20, 2004). "Kinemacolor to Eastmancolor: Faithfully Capturing an Old Technology with a Modern One" Widescren Museum. Retrieved July 8, 2006</ref> Color for feature-length films didn't really come into play until the 1920s with Technicolor's two-color subtractive process, invented by Frederic E. Ives and used in 1922 on Toll of the Sea. Using a beam-splitter prism behind the lens, the system exposed two adjacent frames of black and white film simultaneously, one behind a red filter, the other behind a green filter. Every other frame of the negative was copied to two strips of film (called matrices), which were dyed complementary colors, and cemented together base-to-base. The problem-plagued format lagged until 1928, when Technicolor introduced an imbibition process, like lithography, using the two matrices, coated with hardened gelatin in a relief image, thicker where the image was darker, to transfer color dyes onto a third, blank strip of film. Technicolor re-emerged with a three-color process for cartoons in 1932, and live action in 1934. Using a beam-splitter prism behind the lens, this camera incorporated three individual strips of black and white film, each one behind a filter of one of the primary colors (red, green and blue), allowing the full color spectrum to be recorded.<ref name="widetech">Hart, Martin (2003). "The History of Technicolor" Retrieved July 7, 2006</ref> A printing matrix with a hardened gelatin relief image was made from each negative, and the three matrices transferred color dye onto a blank film to create the print.<ref>Sipley, Louis Walton. (1951). A Half Century of Color The Macmillan Company, New York.</ref>

Although Eastman Kodak had first introduced acetate-based film, it was far too brittle and prone to shrinkage, so the very dangerous nitrate-based celluose films, which had to be handled with extreme care or else they were prone to catching fire and exploding, were generally used for motion picture camera and print films. In the late 1940s Kodak began replacing all of the nitrate-based films with the safer, more robust cellulose triacetate-based films. In 1949 the Academy of Motion Picture Arts and Sciences awarded Kodak with a Scientific and Technical Academy Award (Oscar) for the safer triacetate stock. By 1951, all camera and projector films were triacetate-based. <ref name="tafi">Slide, Anthony (1990). The American Film Industry: A Historical Dictionary. Limelight (1st ed). ISBN 0-87910-139-3</ref> Some robust print films and laboratory films that do not need to be spliced are made from synthetic polyester base.

In 1950 Kodak announced the first Eastman color negative film (along with a complementary positive film) that could record all three primary colors on the same strip of film.<ref>Kodak | Motion Picture Imaging Chronology of Motion Picture Films Retrieved July 10, 2006.</ref>

This "tri-pack" stucture is made up of three separate emulsion layers, one sensitive to red light, one to green and one to blue.

For more on the history and technology of color motion picture film, see Color film (motion picture).

Amateur formats

Eastman Kodak introduced 16 mm film in 1923 as an amateur filmmaking format, which was adopted for use in educational institutions, churches, hospitals and prisons. Super 16 mm was introduced in 1971, which increased the negative size by forty per cent and made it more suitable for blow-up to 35 mm for theatrical release.<ref name="tafi" />

The introduction of 8 mm film followed 16 mm in 1932, intended for amateur filmmaking and "home movies".<ref name="tafi" />

Other common types of photographic films

In addition to black & white and color negative films, there are black & white and color positive films, which when developed create a positive ("natural") image that is projectable. There are also films sensitive to non-visible wavelengths of light, such as infrared.

How film works

Main article: Photographic film
See also Color film (motion picture) and Exposure (photography) and film base

Inside the photographic emulsion are millions of light-sensitive silver halide crystals. Each crystal is a compound of silver plus a halogen (such as bromine, iodine or chlorine) held together in a cubical arrangement by electrical attraction. When the crystal is struck with light, free-moving silver ions build up a small collection of uncharged atoms. These small bits of silver - too small to even be visible under a microscope, are the beginning of a latent image. Developing chemicals use the latent image specs to build up density, an accumulation of enough metallic silver to create a visible image.<ref>Upton, Barbara London with Upton, John (1989). Photography (4th ed). BL Books, Inc./Scott, Foresman and Company. ISBN 0-673-39842-0.</ref>

The emulsion is attached to the film base with a transparent adhesive called the subbing layer. Below the base is an undercoat called the antihalation backing, which usually contains absorber dyes or a thin layer of silver or carbon (called rem-jet on color negative stocks). Without this coating, bright points of light would penetrate the emulsion, reflect off the inner surface of the base, and reexpose the emulsion, creating a halo around these bright areas. The antihalation backing can also serve to reduce static buildup, which was a significant problem with old black and white films. The film, which runs through the camera at 18 inches per second, could build up enough static electricity to actually cause a spark bright enough to expose the film, antihaliation backing solved this problem. Color films have three layers of silver halide emulsions to separately record the red, green and blue information. For every silver halide grain there is a matching color coupler grain. The top layer contains blue-sensitive emulsion, followed by a yellow filter to cancel out blue light - after this comes a green sensitive layer followed by a red sensitive layer.

Just as in black-and-white, the first step in color development converts exposed silver halide grains into metallic silver - except that an equal amount of color dye will be formed as well. The color couplers in the blue-senstitive layer will form yellow dye during processing the green layer will form magenta dye and the red layer will form cyan dye. A bleach step will convert the metallic silver back into silver halide, which is then removed along with the unexposed silver halide in the fixer and wash steps, leaving only color dyes.<ref>Malkiewicz, Kris and Mullen, M. David ASC (2005) Cinematography (3rd ed). Simon Schuester. pp. 49-50. ISBN 0-7432-6438-x</ref>

In the 1980s Eastman Kodak invented the T-Grain, a synthetically manufactured silver halide grain that had a larger, flat surface area and allowed for greater light sensitivity in a smaller, thinner grain. Thus Kodak was able to break the catch 22 of higher speed (greater light sensitivity - see film speed) means larger grain and more "grainy" images. With T-Grain technology, Kodak refined the grain structure of all their "EXR" line of motion picture film stocks<ref>Probst, Christopher (May 2000). "Taking Stock" Part 2 of 2 American Cinematographer Magazine ASC Press. pp. 110-120</ref> (which was eventually incorporated into their "MAX" still stocks). Fuji films followed suit with their own grain innovation, the tabular grain in their SUFG (Super Unified Fine Grain) SuperF negative stocks, which are made up of thin hexagonal tabular grains.<ref>Holben, Jay (April 2000). "Taking Stock" Part 1 of 2 American Cinematographer Magazine ASC Press. pp. 118-130</ref>

Variations in common use

See List of film formats

1.37:1 (1.33:1) "Academy"

In the conventional motion picture format, frames are four perforations tall, with an aspect ratio of about 1.37:1, 22 mm by 16 mm (0.866" x 0.630"). This is a derivation of the aspect ratio and frame size designated by Thomas Edison (24.89 mm by 18.67 mm or .980" by .735") at the dawn of motion pictures, which was an aspect ratio of 1.33:1. In 1928, the advent of sound had brought about a change in the format, and after some initial attempts at using synchronized record cylinders, etc., the sound started to be stored optically directly on the film. To accomodate this strip of sound information, the picture was shifted slightly to the right and shrunk slightly vertically to allow room between the picture and the perforations for the sound. Hence the frame became 22 mm by 16 mm (.866" by .630") with an aspect ratio of 1.37:1. This became known as the "Academy" ratio, named so after the Academy of Motion Picture Arts and Sciences. Although, since the 1950s the aspect ratio of theatrically released motion picture films has been 1.85:1 (1.66:1 in Europe) or 2.35:1 (2.40:1 after 1970), so the "Academy" ratio was relegated to usage primarily for television. The image area for "TV transmission" is slightly smaller than the full "Academy" ratio at 21 mm by 16 mm (0.816" by 0.612"), which is an aspect ratio of 1.33:1. Hence the "Academy" ratio is often mistakenly referred to as having an aspect ratio of 1.33:1, referring to the TV transmitted area, instead of the actual 1.37:1 ratio of the full "Academy" area.

Widescreen

Main article: Anamorphic
See also Aspect ratio (image)

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 (more commonly referred to as 2.40:1. The ratio was 2.35:1 - and is still quite often mistakenly referred to as such - until a SMPTE revision of the standards in 1970). The image, as recorded on the negative and print, is horizontally compressed (squeezed) by a factor of 2.

The unexpected success of the Cinerama widescreen process led to a boom in film format innovations from both studios and individuals looking to capitalize on audience demand for higher quality, lower cost widecreen images. The most successful of these was 20th Century Fox's CinemaScope, one of the earliest popular mainstream anamorphic film process<ref>Samuelson, David W. (September 2003). "Golden Years". American Cinematographer Magazine ASC Press pp. 70-77.</ref> After the main "widescreen" boom of the 1950s, the overall shape of the theatrical screen had been altered by the success of CinemaScope. Films photographed without anamorphic lenses had to find a way to compete and the solution - which became the defacto standard for theatrical films - was to crop off the top and bottom of the frame to create a 1.85:1 "wide" aspect ratio (21.96 mm by 11.33 mm or .825" by .446"). These flat films are photographed with the full Academy frame, but are cropped (most often in the theater projector, not in the camera) to obtain the "wide" aspect ratio. This standard, in some European nations, became 1.66:1 instead of 1.85:1.

The 1950s and 1960s saw many other novel processes such as VistaVision, SuperScope, Technirama, and TechniScope, most of which ultimately became obsolete.

Super 35 mm

Main article: Super 35 mm film

The concept behind Super 35 originated with the Tushinsky Brothers' SuperScope format, particularly the SuperScope 235 specification from 1956. In 1982, Joe Dunton revived the format for Dance Craze, and Technicolor soon marketed it under the name "Super Techniscope" before the industry settled on the name Super 35. The central driving idea behind the process is to return to shooting in the original silent "Edison" 1.33:1 full 4-perf negative area (24.89 mm by 18.67 mm or .980" by .735"), and then crop the frame either from the bottom or the center (like 1.85:1) to create a 2.40:1 aspect ratio (matching that of anamorphic lenses) with an area of 24 mm by 10 mm (.945" by .394"). Although this cropping may seem extreme, by expanding the negative area out perf-to-perf, Super 35 creates a 2.40:1 aspect ratio with an overall negative area of 240 mm2 (9.45"2), only a mere 9 mm2 (.35"2) less than the 1.85:1 crop of the Academy frame (248.81 mm2 or 9.80"2).<ref name="asc">Burum, Stephen H. (ed) (2004). American Cinematographer Manual (9th ed). ASC Press. ISBN 0-935578-24-2</ref> The cropped frame is then converted at the intermediate stage to a 4-perf anamorphically squeezed print compatible with the anamorphic projection standard. This allows an "anamorphic" frame to be captured with non-anamorphic lenses, which are much more common, less expensive, faster, smaller, and optically superior to equivalent anamorphic lenses. Up to 2000, once the film was photographed in Super 35, an optical printer was used to anamorphose (squeeze) the image. This optical step reduced the overall quality of the image and made Super 35 mm a controversial subject among cinematographers, many who preferred the higher image quality and frame negative area of anamorphic photography (especially with regard to granularity). With the advent of Digital intermediates (DI) at the beginning of the 21st century, however, Super 35 mm photography has become even more popular, since the cropping and anamorphosing stages can be done digitally in-computer without creating an additional optical generation with increased grain. As DI becomes less expensive and more popular, it is likely to render Super 35 optical conversions completely obsolete in the near future.

3-Perf

Main article: 3-perf

Most motion pictures today are shot and projected using the 4-perforation format, but cropping the top and bottom of the frames for an aspect ratio of 1.85 or 1.66. In television production, where compatibility with an installed base of 35 mm film projectors is unnecessary, a 3-perf format is sometimes used, giving the 16:9 ratio used by HDTV and reducing film usage by 25 per cent. 3-perf is also sometimes used with Super 35 mm film cameras which utilize the whole negative area between the perforations (not allowing for soundtrack area).

VistaVision

The VistaVision motion picture format, a long-dormant widescreen format that was somewhat revived by George Lucas's Industrial Light and Magic for visual effects for Star Wars, uses a horizontal frame (the subsequent frames are created side-by-side as opposed to the standard vertical format where they are recorded above and below each other) which 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. This format is unprojectable in standard theaters and requires an optical step to squeeze the image (like anamorphic photography) into the standard 4-perf vertical 35 mm frame.

35 mm still photography

Main article: 135 film

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 (1.417" x .945").

Perforations

Film perforations were originally round holes cut into the side of the film, but as these perforations were more subject to wear and deformation, the shape was changed to that now called the Bell & Howell perforation. in 1989 Kodak introduced a stronger version of the Bell & Howell perforation, rounding each corner by 0.005" (.13 mm). This small difference is almost visually imperceptible, but adds strength where the perforation is most vulnerable to tearing.<ref name="hone" />

In 1953, the introduction of CinemaScope required the creation of a different shape of perforation which was nearly square and smaller to provide space for four magnetic sound stripes for stereophonic and surround sound.<ref name="hone" />

The flattened perforations were introduced by around 1900, which remain to this day for original camera negative film. Kodak-Standard perforations were introduced some ten years later for projection use.

Today there are a number of variations in perforation size and shape for different types of film, but the Bell & Howell perf remains the standard for camera negative films.

New innovations in sound

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.

Technical specifications

Areas on 35 mm film
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Areas on 35 mm film

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 frames per second
  • vertical pulldown
  • 4 perforations per frame (except if using 3-perf for origination)

35 mm spherical<ref name="asc" />

  • 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)

Super 35 mm film<ref name="asc" />

  • 1.33 aspect ratio on camera negative
  • camera aperture: 0.980" by 0.735"
  • picture used (35 mm anamorphic): 0.945" (24.00 mm) by 0.394" (10.00 mm)
  • picture used (70 mm blowup): 0.945" (24.00 mm) by 0.430" (10.92 mm)
  • picture used (35 mm flat 1.85): 0.945" (24.00 mm) by 0.511" (12.97 mm)

35mm anamorphic<ref name="asc" />

  • 2.39 aspect ratio, horizontal squeezed to fit 1.37 camera negative
  • camera aperture: 0.866" (22.00 mm) by 0.732" (18.59 mm)
  • projector aperture: 0.825" (20.96 mm) by 0.690" (17.53 mm)

See also

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