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Film stock is the term for photographic film on which motion pictures are shot. 1889-1900 Modern motion picture film stock was first created thanks to the introduction of a transparent flexible film base material, celluloid, which was discovered and refined for photographic use thanks to the work of John Carbutt, Hannibal Goodwin, and George Eastman. Prior to this, most motion picture experiments were performed using paper roll film, which made it difficult if not impossible to view the developed film as a single continuous moving image without other complex apparatuses. Furthermore, the paper film was much more fragile than celluloid. Eastman Kodak would become the first to make celluloid film commerically available, starting in 1889; Thomas Henry Blair emerged in 1891 as the first major competitor for supplying celluloid film. The stock had a frosted base in order to facilitate easier viewing by transmitted back light. By November of 1891 William Dickson at Edison's lab was using Blair's stock for Kinetoscope tests, and Blair's company remained a main supplier of film to the Edison lab for the next five years. Blair's operation was also crucial to the continued development of motion picture technology through 1892 and 1893, due to temporary shutdowns at Eastman because of problems with their production setup. Eventually patent lawsuits in 1893 led to Blair moving to England, which allowed Eastman to gradually fill the entirety of the Edison lab's film orders. Blair's new headquarters allowed him to supply many of the key European filmmaking pioneers, including Birt Acres, Robert Paul, George Albert Smith, Charles Urban, and the Lumiere Brothers. This was to be shortlived, however, as by 1896 the new movie projector would demand a fully transparent film base that Blair had difficultly supplying. Eastman shortly thereafter bought the company out, thus consolidating its position as the leading supplier of film stock from then on. Eastman's first motion picture film stock incorporated the same emulsion as was used for its still film, which was, like nearly all film emulsion of the time, orthochromatic-sensitive. Film at this point did not have a strictly defined speed; rather, the orthochromatic quality of the stock allowed the film to be processed under a red safelight, while the density was checked as development was occurring. Standard practice until the end of the silent era involved tearing off several inches from the start of each shot and testing development on it. Positive stock was created which would be slower, finer-grained, and of a higher contrast than a negative; all of these characteristics remain consistent to this day. From 1895, Eastman supplied their motion picture roll film in rolls of 65 feet, while Blair's rolls were 75 feet. If longer lengths were needed, the unexposed negative rolls could be cemented in a darkroom, but this was largely undesirable by most narrative filmmakers. Actuality films were much more eager to undertake this method, however, in order to depict longer actions, and created cemented rolls as long as 1000 feet. American Mutoscope and Biograph was the first known company to use this, for the Jeffries-Sharkey fight on November 3, 1899. Classification and properties There are several variables in classifying stocks; in practice, one orders raw stock by a code number, based on desired sensitivity to light. Base A piece of film consists of a light-sensitive emulsion applied to a tough, transparent base, attached to anti-halation backing. Originally the highly flammable cellulose nitrate was used. In the 1930s, film manufacturers introduced "safety film" with a cellulose triacetate plastic base. All amateur film stocks were safety film, but the use of nitrate persisted for professional releases. Kodak discontinued the manufacture of nitrate base in 1951, and the industry transitioned entirely to safety film in 1951 in the United States and by 1955 internationally. Since the 1980s a growing number of films have used polyester film stock. Emulsion The emulsion is comprised of silver halide grains suspended in a gelatin colloid; in the case of color film, there are three layers of silver halide which are mixed with color couplers and interlayers which filter specific light spectra. These end up creating yellow, cyan, and magenta layers in the negative after development. Chemistry Development chemistry may produce either a positive or negative image. Camera films that produce a positive image are known as reversal films; processed film of this type can typically be directly projected. Negative films require additional transferring; since negative films are much more commonly used, terms are based on the steps needed to produce a viewable finished print: one speaks of negatives and positives. Image record Different emulsions and development processes exist for a variety of image recording possibilities: the two most common of which are black and white and color. However, there are also variant types, such as infrared film (in black and white or color); specialist technical films, such as those used for X-rays; and obsolete processes, such as orthochromatic film. Generally, however, the vast majority of stock used today is "normal" (visible spectrum) color, although "normal" black and white also commands a significant minority percentage. Physical characteristics Film is also classified according to its gauge and the arrangement of its perforations— gauges range from 8 mm to 70 mm or more, while perforations may vary in shape, pitch, and positioning. The film is also distinguished by how it is wound with regard to perforations and base or emulsion side, as well as whether it is packaged around a core, a daylight spool, or within a cartridge. Depending on the manufacturing processes and camera equipment, lengths can vary anywhere from 25 to 2000 feet. Common lengths include 25 feet for 8 mm, 50 feet for Super 8, 100 and 400 feet for 16 mm, 400 and 1000 feet for 35 mm, and 1000 for 65/70 mm. Responsivity A critical property of a stock is its film speed, determined by ASA or its sensitivity to light listed by a measurement on the raw stock which must be chosen with care. Speed determines the range of lighting conditions under which the film can be shot, and is related to granularity and contrast, which influence the look of the image. Color temperature Another important quality of color film stock in particular is its color balance, which is defined by the color temperature at which it accurately records white. Tungsten lighting is defined at 3200 K, which is considered "warmer" in tone and shifted towards orange; daylight is defined at 5500 K, which is considered "colder" and shifted towards blue. This means that unfiltered tungsten stock will look normal shot under tungsten lights, but blue if shot during daylight. Obversely, daylight stock shot in daylight will look normal, but orange if shot under tungsten lights. Color temperature issues such as these can be compensated for by other factors such as lens filters and color gels placed in front of the lights. The color temperature of a film stock is generally indicated next to the film speed number - e.g. 500T stock is color film stock with an ASA of 500 and balanced for tungsten light; 250D would have an ASA of 250 and be balanced for daylight. Deterioration Motion picture film is known to be a highly unstable medium: improperly preserved film can deteriorate in a period of time much faster than many photographs or other visual presentations. Owners of home-made films often find that their film can become brittle and unwatchable in the space of a few years. Decaying film stock gives off an odor similar to that of vinegar, which is why film buffs often refer to such decaying as "vinegar syndrome." Intermediate and print stocks The distinction between camera stocks and print stocks involves a difference in the recording process. When the answer print has been approved, the original camera negative (OCN) is assembled by a negative cutter using the answer print as a guide. Interpositive (IP) prints are struck from the negative, and each IP is then used to make several Dupe Negative (DN) copies. The release prints are then generated from the DNs. Recently, with the development of digital intermediate (DI), it has become possible to completely edit, composite visual effects, and color grade the image digitally at full resolution and bit-depth. In this workflow, the answer print is generated digitally and then written out to the IP stage using a laser film printer. Due to the specialized nature of the exposure and the higher degree of control afforded by the film lab equipment, these intermediate and release stocks are specially designed solely for these applications and are generally not feasible for camera shooting. Because intermediates only function to maintain the image information accurately across duplication, each manufacturer tends to only produce one or two different intermediate stocks. Similarly, release print stocks usually are available only in two varieties: a "normal" print or a deluxe print with greater latitude and contrast. Video to film Lately it has become possible to transfer video images, including films scanned at high resolution, back to film stocks by making a digital intermediate, which can then be recorded out to a film interpositive with a laser film printer. The first major live-action film to use this process entirely was O Brother Where Art Thou. Prior to this, the video master was transferred from tape to film through one of several methods: CRT recorder, laser film printer, Kinescope, or electron beam recorder (EBR). Theater performances have been preserved with Kinescope for many years—the 1964 New York production of Hamlet with Richard Burton, for example, was shot on video and printed as a film that was released in movie theaters using this process. Also, independent filmmaker Rob Nilsson's 1986 film Signal Seven was originally shot on 3/4" videocassette, and then transferred to film, being one of the first independent films originally to be shot on videotape. Also, countless educational, medical, industrial, and promotional videotapes produced from the late 1950s up to the mid-1980s were also transferred to film stock (usually 16mm film) for widespread distribution, using either an EBR or CRT recorder. This was done due to VCRs and VTRs then not being commonplace in most schools, hospitals, boardrooms, and other institutional settings, due to their high cost and the multitudes of proprietary (and incompatible) open-reel & cassette videotape formats in the early years of industrial-market videotape recorders. But 16mm projectors were widely available at the time in such settings, making distribution of such video productions on 16mm film more practical. This was the case until the mid-1980s, when the VCR became affordable enough (and much more standardized in the form of VHS and Betamax) to be adopted in such institutional settings on a widespread basis. Digital video equipment has made this approach easier; theatrical-release documentaries and features originated on video are now being produced this way. See also | |||||||
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