Film stock
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Film stock is the term for photographic film on which motion pictures are shot.
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[edit] History
[edit] 1889-1899
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 commercially 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, and the emulsions from each company were orthochromatic. 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 leaving his American company and starting again in 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. The American Blair company was to be shortlived, however, as by 1896 the new movie projector would demand a fully transparent film base that they had difficultly supplying. Eastman shortly thereafter bought the company out, thus consolidating its position as the leading supplier of film stock from then on. These developments also led Louis Lumiere to work with Victor Planchon on adapting the Lumiere "Blue Label" (Etiquette Bleue) photographic plate emulsion for use on celluloid roll film, which began in early 1896 and was brought to full production capacity by the following year.
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.
[edit] 1900-1920
Work on improved film stocks was rather slow in the first decade of the new century, as the equipment and formats, particularly, were still in the process of gradually standardizing. With a large number of differing film gauges in use, supplying a market still in its infancy was likely a difficult task, and Eastman was able to retain the majority of the market share without making major adjustments to the emulsion; their only major change was to increase the length of rolls to 200 feet. Lumiere, on the other hand, reformulated their stock to match the speed of Eastman film, which became known as "Violet Label" (Etiquette Violette). Blair retired back to the United States after selling his English company to Pathe in 1907, who began using the facilities for producing their own film stock. This sale had future repercussions among film preservation, as Pathe began to supplement their operation in 1910 by purchasing film prints in order to strip the silver and emulsion from the film base for recoating.
As the quantity of film and filmmakers grew in these early years, the demand for standardization increased in prominence. 35 mm, largely thanks to the popularity of the Edison and Lumiere camera lines (and their often unauthorized clones) had begun to stabilize as the dominant gauge, but still was usually purchased unperforated, and subsequently punched by the consumer with perforation equipment designed by third parties. Although Edison (4 square perfs per frame on each side) and Lumiere (1 rounded perf per frame on each side) formats - based on the camera designs - were the most common, the perforators were not always precise, and it could be difficult to create prints for the opposite perforation format. Edison's organization of the Motion Picture Patents Trust, though largely ineffective in controlling the burgeoning film industry, was able in 1909 to agree to what would become the de facto standard: 35 mm gauge film, with Edison perforations and a 1.33 aspect ratio. These parameters have remained largely constant to the present day.[1]
The Bell and Howell company perforators entered the market in 1908 and very shortly were recognized as exceptional enough to pervade the American industry. Eastman Kodak was also quick to opt to use the machine to pre-perforate their films, which assured the perforation specifications being adopted as the world standard not long after. These perforations, known as BH-type, remain the standard for original camera negative film.
The belle epoque era also saw the creation of numerous small, local film suppliers, the vast majority of which were short-lived due to their smaller production batches, slower emulsions (which were also usually blue-only sensitive rather than orthochromatic), and inferior quality control. Among these companies, Agfa began to produce motion picture film in 1913, but remained a largely local supplier until post-WWI boycotts of popular French films allowed the newly-founded UFA film studio to flourish and thus boosted Agfa's orders.
[edit] 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.
[edit] 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.
[edit] 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.
[edit] 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.
[edit] 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.
[edit] 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.
[edit] 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.
[edit] 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.
[edit] 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."
[edit] 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 (on more-costly print film like Kodak Vision Premiere) with slightly greater saturation and contrast. The latter prints are typically reserved for use only in the largest theaters in New York and Los Angeles, as well as some screenings for critics and other industry insiders.
[edit] 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 fine-grain film intermediate with a laser film printer. The first major live-action film to use this process entirely was O Brother Where Art Thou, done by Kodak's now-defunct Cinesite division in Hollywood in the spring of 2000. 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.
Technicolor also experimented in the early 1970s with using video gear & videotape to make feaure-length motion pictures with, by transferring the videotape to film for final release and distribution. Films made with this process were the 1973 film Why, the 1971 film The Resurrection of Zachary Wheeler, and the most famous film using this process, Frank Zappa's 1971 film 200 Motels.
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. High Definition video became popular in the early 2000s by pioneering filmmakers like George Lucas and Robert Rodriguez, who used HD video cameras to capture images for popular movies like Star Wars Episode 2: Attack of the Clones and Spy Kids 2, respectively, both released in 2002.
Independent filmmakers, especially those participating in the Dogme movement of filmmaking, have also shot their films on MiniDV videotape, to be transferred to 35mm film stock for theatrical release. Some examples of independent movies being shot on videotape are Lone Scherfig's Italian For Beginners (a Dogme film), Steven Soderbergh's Full Frontal (which was shot on PAL-standard MiniDV gear in the normally NTSC-prevalent US, due to its higher resolution of 625 lines, and a frame rate of 25 fps, which more closely matches film's 24 fps), and Mike Figgis' Timecode. 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.
[edit] See also
[edit] Notes
- ^ The gauge and perforations are more or less identical to modern film stock; the full silent ratio is also generally still used as the film gate in movie cameras, although portions of the image are later cropped out in post-production and projection.
[edit] References
- Ascher, Steve and Edward Pincus. The Filmmaker's Handbook: A Comprehensive Guide for the Digital Age. New York: Penguin Group, 1999.
- Salt, Barry. Film Style and Technology: History and Analysis. London: Starword, 1992.
