35 mm film is the basic film gauge 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 35 millimeters (about 1 3/8 inches) wide — hence the name. The standard negative pulldown for movies ("single-frame" format) is four perforations per frame along both edges, which makes for exactly 16 frames per foot (for stills, the standard frame is eight perforations).
A wide variety of largely proprietary gauges were used by the numerous camera and projection systems invented independently in the late 19th century and early 20th century, ranging from 13 mm to 75 mm (0.51–2.95 in). 35 mm was eventually recognized as the international standard gauge in 1909, and has remained by far the dominant film gauge for image origination and projection despite threats from smaller and larger gauges, and from novel formats, because its size allows for a relatively good tradeoff between the cost of the film stock and the quality of the images captured. The ubiquity of 35 mm movie projectors in commercial movie theaters makes it the only motion picture format, film or video, that can be played in almost any cinema in the world.
The gauge is remarkably versatile in application. In the past one hundred years, 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. Since the beginning of the 21st century, Eastman Kodak and Fujifilm have held a duopoly in the manufacture of 35 mm motion picture film.
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's invention of nitrocellulose film base in 1887 was the first transparent, flexible film; the following year, Emile Reynaud developed the first perforated film stock. Eastman was the first major company, however, to mass-produce these components, 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 Alva 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 W. K. L. 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 Blair Camera Co. supplied Edison with 1 9/16–inch filmstock that would be trimmed and perforated at the Edison lab to create 35 mm gauge filmstrips (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 4 perforations high. 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. 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. It was Edison's format, however, that became first the de facto standard and then, in 1909, the "official" standard of the newly formed Motion Picture Patents Company, a trust established by Edison. Scholar Paul C. Spehr describes the importance of these developments:
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 specks to build up density, an accumulation of enough metallic silver to create a visible image.
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; antihalation 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-sensitive 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.
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 problem of higher speed (greater light sensitivity — see film speed) which required larger grain and therefore more "grainy" images. With T-Grain technology, Kodak refined the grain structure of all their "EXR" line of motion picture film stocks (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.
In addition to black & white and color negative films, there are black & white and color reversal 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.
Originally, film was a strip of cellulose nitrate coated with black-and-white photographic emulsion. 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. 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. But any process that photographed and projected the colors sequentially was subject to color "fringing" around moving objects, and a general color flickering.
In 1916, William Van Doren Kelley produced the first commercially successful American color system using 35 mm film called Prizma. Initially a system that used frame sequential photography and projected through additive synthesis, Prizma was refined to bi-pack photography, with two strips of film (one sensitized for red and one for blue) threaded as one through the camera. The method of projection was also changed: each record was printed and processed on duplitized stock, creating a successful subtractive color process. This basic principle behind color photography set the standard for many later successful color formats, such as Multicolor, Brewster Color, and Cinecolor.
Although color was available for years prior, color in Hollywood feature films became popular with Technicolor, whose main advantage was quality prints in shorter time than its competitors. In its earliest conception, Technicolor was a two-color system, recording red and green. 1922's Toll of the Sea was the first film printed in their subtractive color system. Unlike Kinemacolor, which recorded color frame-sequentially, Technicolor's camera recorded red and green frames simultaneously through a beam splitting prism onto one strip of film. Two prints on half-width stock were processed from this negative, and one was toned red, and the other toned green. The two strips were then cemented together, forming a single strip similar to duplitized film.
In 1928, Technicolor introduced imbibition printing (similar to lithography) that streamlined the process. Using two matrices coated with hardened gelatin in a relief image, thicker where the image was darker, aniline color dyes were transferred onto a third, blank strip of film.
In 1934, William T. Crispinel and Alan M. Gundelfinger revived the Multicolor process under the company name Cinecolor. Cinecolor enjoyed large success in animation and low-budget pictures, largely due to its inexpense and good image results. But while Cinecolor used the same duplitized stock method as Prizma and Multicolor, its main advantage was inventing processing machines that could do larger quantities of film in a shorter time.
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. 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.
In 1950 Kodak announced the first Eastman color 35 mm negative film (along with a complementary positive film) that could record all three primary colors on the same strip of film. An improved version in 1952 was quickly adopted by Hollywood, making the use of tri-strip Technicolor cameras and bi-pack cameras (utilized in two-color systems such as Cinecolor) obsolete in color cinematography. This "monopack" structure is made up of three separate emulsion layers, one sensitive to red light, one to green and one to blue.
Although Eastman Kodak had first introduced acetate-based film, it was far too brittle and prone to shrinkage, so the dangerously flammable nitrate-based cellulose films were generally used for motion picture camera and print films. In 1949 Kodak began replacing all of the nitrate-based films with the safer, more robust cellulose triacetate-based "Safety" films. In 1950 the Academy of Motion Picture Arts and Sciences awarded Kodak with a Scientific and Technical Academy Award (Oscar) for the safer triacetate stock. By 1952, all camera and projector films were triacetate-based. Most if not all film prints today are made from synthetic polyester safety base (which started replacing Triacetate film for prints in the early 1990s). Ironically, the downside of polyester film is that it is extremely strong, and, in case of a fault, will stretch and not break–potentially causing damage to the projector and ruining a fairly large stretch of film: 2–3 ft or ~2 sec. Also, polyester film will melt if exposed to the projector lamp for too long. Original camera negative is still generally made on a triacetate base.
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 in × 0.630 in). This is a derivation of the aspect ratio and frame size designated by Thomas Edison (24.89 mm by 18.67 mm or 0.980 in by 0.735 in) at the dawn of motion pictures, which was an aspect ratio of 1.33:1. The first sound features were released in 1926–27, and while Warner Bros. was using synchronized phonograph discs (sound-on-disc), Fox placed the soundtrack in an optical record directly on the film (sound-on-film) on a strip between the sprocket holes and the image frame. "Sound-on-film" was soon adopted by the other Hollywood studios, resulting in an almost square image ratio.
In 1932, to restore a more rectangular image ratio, the picture was shrunk slightly vertically, with the line between frames thickened. Hence the frame became 22 mm by 16 mm (0.866 in by 0.630 in) 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. 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 in by 0.612 in), 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.
The commonly used anamorphic 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 projection 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 in 1952 led to a boom in film format innovations in order to compete with the growing audiences of television and the dwindling audiences in movie theaters. These processes could give theatergoers an experience that television couldn't-- color, stereophonic sound and panoramic vision. Before the end of the year, 20th Century Fox had narrowly "won" a race to obtain an anamorphic optical system invented by Henri Chrétien, and soon began promoting the Cinemascope technology as early as the production phase.
Looking for a similar alternative, other major studios hit upon a simpler, less expensive solution by May 1953: using a removable aperture plate in the film projector gate, the top and bottom of the frame could be cropped to create a wider aspect ratio. Paramount Studios began this trend with their aspect ratio of 1.66:1, first used in Shane, which was originally shot for Academy ratio. It was Universal Studios, however, with their May release of Thunder Bay that introduced the now standard 1.85:1 format to American audiences and brought attention to the industry the capability and low cost of equipping theaters for this transition.
Other studios followed suit with aspect ratios of 1.75:1 up to 2:1. For a time, these various ratios were used by different studios in different productions, but by 1956, the aspect ratio of 1.85:1 became the "standard" US format. These flat films are photographed with the full Academy frame, but are matted (most often with a mask 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, although some productions with pre-determined American distributors compose for the latter in order to appeal to US markets.
In September 1953, 20th Century Fox debuted CinemaScope with their production of The Robe to great success. CinemaScope became the first marketable usage of an anamorphic widescreen process and became the basis for a host of "formats," usually suffixed with -scope, that were otherwise identical in specification, although sometimes inferior in optical quality. (Some developments, such as SuperScope and Techniscope, however, were truly entirely different formats.) By the early 1960s, however, Panavision would eventually solve many of the Cinemascope lenses' technical limitations with their own lenses, and by 1967, Cinemascope was retired in favor of Panavision and other third-party manufacturers.
The 1950s and 1960s saw many other novel processes utilizing 35 mm, such as VistaVision, SuperScope, Technirama, and Techniscope, most of which ultimately became obsolete. VistaVision, however, would be revived decades later by Lucasfilm and other studios for special effects work, while a SuperScope variant became the predecessor to the modern Super 35 format that is popular today.
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 0.980 in by 0.735 in), 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 (0.945 in by 0.394 in). 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 square millimetres (0.372 sq in), only 9 mm² (0.014 sq in) less than the 1.85:1 crop of the Academy frame (248.81 mm² or 0.386 sq in). 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 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 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.
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 — if used with Super 35 — the 16:9 ratio used by HDTV and reducing film usage by 25 percent. Because of 3-perf's incompatibility with standard 4-perf equipment, it can utilize the whole negative area between the perforations (Super 35 mm film) without worrying about compatibility with existing equipment; the Super 35 image area includes what would be the soundtrack area in a standard print. All 3-perf negatives require optical or digital conversion to standard 4-perf if a film print is desired, though 3-perf can easily be transferred to video with little to no difficulty by modern telecine or film scanners. With digital intermediate increasingly becoming a standard process for post-production, 3-perf has become more popular with productions which would otherwise be averse to an optical conversion stage.
The VistaVision motion picture format was created in 1954 by Paramount Pictures in order to create a finer-grained negative and print for flat widescreen films. Similar to still photography, the format uses a camera running 35 mm film horizontally instead of vertically through the camera, with frames that are eight perforations long, resulting in a wider aspect ratio of 1.5:1 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 into the standard 4-perf vertical 35 mm frame.
While the format was dormant by the early 1960s, the camera system was somewhat revived for visual effects by John Dykstra at Industrial Light and Magic, starting with Star Wars, as a means of reducing granularity in the optical printer by having increased original camera negative area at the point of image origination. Its usage has again declined since the dominance of computer-based visual effects, although it still sees very limited utilization.
BH perfs: Film perforations were originally round holes cut into the side of the film, but as these perforations were subject to wear and deformation, the shape was changed to what is now called the Bell & Howell (BH) perforation, which has straight top and bottom edges and outward curving sides. The BH perforation's dimensions are 0.110 inches (2.79 mm) from the middle of the side curve to opposite top corner by 0.073 inches (1.85 mm) in height. The BH1866 perforation, or BH perforation with a pitch of , is the modern standard for negative and internegative films.
KS perfs: Because BH perfs have sharp corners, the repeated use of the film through intermittent movement projectors creates strain that can easily tear the perforations. Furthermore, they tended to shrink as the print slowly decayed. Therefore, larger perforations with a rectangular base and rounded corners were introduced by Kodak in 1924 to improve steadiness, registration, durability, and longevity. Known as "Kodak Standard" (KS), they are 0.0780 inches (1.981 mm) high by 0.1100 inches (2.794 mm) wide. Their durability makes KS perfs the ideal choice for intermediate and release prints, as well as original camera negatives which require special use, such as high-speed filming, bluescreen, front projection, rear projection, and matte work. The increased height also means that the image registration was considerably less accurate than BH perfs, which remains the standard for negatives. The KS1870 perforation, or KS perforation with a pitch of , is the modern standard for release prints.
These two perforations have remained by far the most commonly-used ones. BH and KS are also are known as N (negative) and P (positive) perforations, respectively. The Bell & Howell perf remains the standard for camera negative films because of its perforation dimensions in comparison to most printers, thus having the ability to keep a steady image compared to other perforations.
DH perfs: The Dubray Howell (DH) perforation was first suggested in 1931 to replace both the BH and KS perfs with a single standard perforation which was a hybrid of the two in shape and size, being like KS a rectangle with rounded corners and a width of 0.1100 inches (2.79 mm), but with BH's height of 0.073 inches (1.85 mm). This gave it longer projection life but also improved registration. One of its primary applications was usage in Technicolor's dye imbibition printing (dye transfer). The DH perf never caught on, and Kodak's introduction of monopack Eastmancolor film in the 1950s reduced the demand for dye transfer, although the DH perf persists in certain special application intermediate films to this day.
CS perfs: 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. These perfs are commonly referred to as CinemaScope (CS) or "fox hole" perfs. Their dimensions are 0.0780" (1.85 mm) in width by 0.0730" (1.98 mm) in height. Due to the size difference, CS perfed film cannot be run through a projector with standard KS sprocket teeth, but KS prints can be run on sprockets with CS teeth. Shrunken film with KS prints that would normally be damaged in a projector with KS sprockets may sometimes be run far more gently through a projector with CS sprockets because of the smaller size of the teeth. Though CS perfs have not been widely used since the late 1950s, Kodak still retains CS perfs as a special-order option on at least one type of print stock.
During continuous contact printing, the raw stock and the negative are placed next to one another around the sprocket wheel of the printer. The negative, which is the closer of the two to the sprocket wheel (thus creating a slightly shorter path), must have a marginally shorter pitch between perforations (0.1866 in pitch); the raw stock has a long pitch (0.1870 in). While cellulose nitrate and cellulose diacetate stocks used to shrink during processing slightly enough to have this difference naturally occur, modern safety stocks do not shrink at the same rate, and therefore negative (and some intermediate) stocks are perforated at a pitch of 0.2% shorter than print stock.
New digital soundtracks introduced since the 1990s include Dolby Digital, which is stored between the perforations on the sound side; SDDS, stored in two redundant strips along the outside edges (beyond the perforations); and DTS, in which sound data is stored on separate compact discs synchronized by a timecode track stored 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 optical track technology has also changed: distributors and theaters are changing to cyan dye optical soundtracks instead of black and white (silver) tracks, which are less environmentally friendly. This requires replacing the incandescent exciter lamp with a complementary colored red LED or laser, which is backwards-compatible with older tracks. (The cyan tracks do not register well through older photo-sensors.) The film Anything Else (2003) was the first to be released with only cyan tracks. The transition is expected to be completed by the end of 2007 and has already happened in most multiplexes.
Technical specifications for 35 mm film are standardized by SMPTE.
35 mm spherical
Super 35 mm film
35 mm anamorphic