Polavision was an "instant" color home movie system launched by Polaroid in 1977.
99-485: Unlike other motion picture film stock of the time, Polavision film reproduces color by the additive method, like the much earlier Dufaycolor film. In essence, it consists of a black-and-white emulsion on a film base covered with microscopically narrow red, green and blue filter stripes. It was instant in the sense that it could be very quickly and easily developed in the Polavision processing unit after it
198-428: A PET (polyethylene terephthalate) plastic film base. Films with a triacetate base can suffer from vinegar syndrome , a decomposition process accelerated by warm and humid conditions, that releases acetic acid which is the characteristic component of vinegar, imparting the film a strong vinegar smell, accelerating damage within the film and possibly even damaging surrounding metal and films. Films are usually spliced using
297-447: A certain filter, assume ISO 25 under daylight and ISO 64 under tungsten lighting"). This allows a light meter to be used to estimate an exposure. The focal point for IR is slightly farther away from the camera than visible light, and UV slightly closer; this must be compensated for when focusing. Apochromatic lenses are sometimes recommended due to their improved focusing across the spectrum. Film optimized for detecting X-ray radiation
396-419: A color film, the by-products of the development reaction simultaneously combine with chemicals known as color couplers that are included either in the film itself or in the developer solution to form colored dyes. Because the by-products are created in direct proportion to the amount of exposure and development, the dye clouds formed are also in proportion to the exposure and development. Following development,
495-408: A complex development process, with multiple dyeing steps as each color layer was processed separately. 1936 also saw the launch of Agfa Color Neu, the first subtractive three-color reversal film for movie and still camera use to incorporate color dye couplers, which could be processed at the same time by a single color developer. The film had some 278 patents. The incorporation of color couplers formed
594-424: A faster film. A film with a particular ISO rating can be push-processed , or "pushed", to behave like a film with a higher ISO, by developing for a longer amount of time or at a higher temperature than usual. More rarely, a film can be "pulled" to behave like a "slower" film. Pushing generally coarsens grain and increases contrast, reducing dynamic range, to the detriment of overall quality. Nevertheless, it can be
693-435: A feature that was eventually adapted by all camera and film manufacturers. DX encoding provides information on both the film cassette and on the film regarding the type of film, number of exposures, speed (ISO/ASA rating) of the film. It consists of three types of identification. First is a barcode near the film opening of the cassette, identifying the manufacturer, film type and processing method ( see image below left ). This
792-465: A few special applications as an alternative to the hazardous nitrate film, which had the advantages of being considerably tougher, slightly more transparent, and cheaper. The changeover was completed for X-ray films in 1933, but although safety film was always used for 16 mm and 8 mm home movies, nitrate film remained standard for theatrical 35 mm films until it was finally discontinued in 1951. Hurter and Driffield began pioneering work on
891-422: A film screening when a frame becomes stuck in the projector's film gate. Acetate films are also subject to degradation over time. With exposure to heat, moisture, or acids, the acetyl groups are broken from their molecular bonds to the cellulose. The now free acetic acid is released into the air. Acetic acid is vinegar, and thus the characteristic smell of vinegar is detected. This is known as vinegar syndrome . As
990-474: A flammable gas, becomes sticky and, at a late stage of decomposition, the film oozes a gooey fluid, ultimately leading the substance to become dust. As this occurs, the possibility of auto-ignition increases further. Projection booth fires were not uncommon in the early decades of cinema if a film managed to be exposed to too much heat while passing through the projector's film gate, and several incidents of this type resulted in audience deaths by flame, smoke, or
1089-528: A linear response through the effective exposure range). The sensitivity (i.e., the ISO speed) of a film can be affected by changing the length or temperature of development, which would move the H&;D curve to the left or right ( see figure ). If parts of the image are exposed heavily enough to approach the maximum density possible for a print film, then they will begin losing the ability to show tonal variations in
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#17327810410161188-462: A nitrate base was the first transparent flexible plasticized base commercially available, thanks to celluloid developments by John Carbutt , Hannibal Goodwin , and Eastman Kodak in the 1880s. Eastman was the first to manufacture the film stock for public sale, in 1889. Unfortunately, nitrate also had the serious drawback of being extremely flammable, the characteristic that made it a suitable substitute for gunpowder. It gradually decomposes producing
1287-598: A nitrate base. A report published by the United States Library of Congress in September 2013 states that 70 percent of all American silent feature films are lost. In the literature of photography "acetate" is used as a synonym for several chemicals: cellulose acetate , cellulose triacetate , cellulose diacetate , cellulose acetate propionate , and cellulose acetate butyrate . All have been used separately and in mixtures, to produce film base. Despite
1386-462: A number of disadvantages as a scientific detector: it is difficult to calibrate for photometry , it is not re-usable, it requires careful handling (including temperature and humidity control) for best calibration, and the film must physically be returned to the laboratory and processed. Against this, photographic film can be made with a higher spatial resolution than any other type of imaging detector, and, because of its logarithmic response to light, has
1485-571: A result, the relative tonal values in a scene registered roughly as they would appear if viewed through a piece of deep blue glass. Blue skies with interesting cloud formations photographed as a white blank. Any detail visible in masses of green foliage was due mainly to the colorless surface gloss. Bright yellows and reds appeared nearly black. Most skin tones came out unnaturally dark, and uneven or freckled complexions were exaggerated. Photographers sometimes compensated by adding in skies from separate negatives that had been exposed and processed to optimize
1584-433: A single color of light and allow all others to pass through. Because of these colored couplers, the developed film appears orange. Colored couplers mean that corrections through color filters need to be applied to the image before printing. Printing can be carried out by using an optical enlarger, or by scanning the image, correcting it using software and printing it using a digital printer. Kodachrome films have no couplers;
1683-467: A single photon striking a grain (based on the size of the grains and how closely spaced they are), and density is the proportion of grains that have been hit by at least one photon. The relationship between density and log exposure is linear for photographic films except at the extreme ranges of maximum exposure (D-max) and minimum exposure (D-min) on an H&D curve, so the curve is characteristically S-shaped (as opposed to digital camera sensors which have
1782-415: A small television, it projects the inserted film cartridge onto its translucent screen from behind, but critics from publications like Consumer Reports called the images "murky and dark". Despite this (or perhaps because of it), the format was used by artists, including Charles and Ray Eames , Stan Brakhage and Andy Warhol . One market niche Polaroid promoted was the field of industrial testing, where
1881-430: A special adhesive tape; those with PET layers can be ultrasonically spliced or their ends melted and then spliced. The emulsion layers of films are made by dissolving pure silver in nitric acid to form silver nitrate crystals, which are mixed with other chemicals to form silver halide grains, which are then suspended in gelatin and applied to the film base. The size and hence the light sensitivity of these grains determines
1980-464: A triangle with or without clipped edges; this type of crystal is known as a T-grain crystal or a tabular grain (T-grains). Films using T-grains are more sensitive to light without using more silver halide since they increase the surface area exposed to light by making the crystals flatter and larger in footprint instead of simply increasing their volume. T-grains can also have a hexagonal shape. These grains also have reduced sensitivity to blue light which
2079-870: A useful tradeoff in difficult shooting environments, if the alternative is no usable shot at all. Instant photography, as popularized by Polaroid , uses a special type of camera and film that automates and integrates development, without the need of further equipment or chemicals. This process is carried out immediately after exposure, as opposed to regular film, which is developed afterwards and requires additional chemicals. See instant film . Films can be made to record non- visible ultraviolet (UV) and infrared (IR) radiation. These films generally require special equipment; for example, most photographic lenses are made of glass and will therefore filter out most ultraviolet light. Instead, expensive lenses made of quartz must be used. Infrared films may be shot in standard cameras using an infrared band- or long-pass filters , although
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#17327810410162178-455: A wider dynamic range than most digital detectors. For example, Agfa 10E56 holographic film has a resolution of over 4,000 lines/mm – equivalent to a pixel size of 0.125 micrometers – and an active dynamic range of over five orders of magnitude in brightness, compared to typical scientific CCDs that might have pixels of about 10 micrometers and a dynamic range of 3–4 orders of magnitude. Special films are used for
2277-440: Is a strip or sheet of transparent film base coated on one side with a gelatin emulsion containing microscopically small light-sensitive silver halide crystals. The sizes and other characteristics of the crystals determine the sensitivity, contrast, and resolution of the film. Film is typically segmented in frames , that give rise to separate photographs . The emulsion will gradually darken if left exposed to light, but
2376-543: Is also similar to photographic film. There are several types of photographic film, including: In order to produce a usable image, the film needs to be exposed properly. The amount of exposure variation that a given film can tolerate, while still producing an acceptable level of quality, is called its exposure latitude . Color print film generally has greater exposure latitude than other types of film. Additionally, because print film must be printed to be viewed, after-the-fact corrections for imperfect exposure are possible during
2475-481: Is an advantage since silver halide is most sensitive to blue light than other colors of light. This was traditionally solved by the addition of a blue-blocking filter layer in the film emulsion, but T-grains have allowed this layer to be removed. Also the grains may have a "core" and "shell" where the core, made of silver iodobromide, has higher iodine content than the shell, which improves light sensitivity, these grains are known as Σ-Grains. The exact silver halide used
2574-403: Is blue light). The sensitizing dyes are absorbed at dislocations in the silver halide particles in the emulsion on the film. The sensitizing dyes may be supersensitized with a supersensitizing dye, that assists the function of the sensitizing dye and improves the efficiency of photon capture by silver halide. Each layer has a different type of color dye forming coupler: in the blue sensitive layer,
2673-464: Is by destroying the cartridge and projecting the removed film with an ordinary super 8 mm projector or transferring it to video with a telecine system. The Polavision system was a major commercial failure , and was discontinued in 1979. However, the underlying technology was improved and used as the basis for the Polachrome instant color transparency system introduced in 1983. Due to
2772-543: Is commonly used for medical radiography and industrial radiography by placing the subject between the film and a source of X-rays or gamma rays, without a lens, as if a translucent object were imaged by being placed between a light source and standard film. Unlike other types of film, X-ray film has a sensitive emulsion on both sides of the carrier material. This reduces the X-ray exposure for an acceptable image – a desirable feature in medical radiography. The film
2871-414: Is done by making couplers with a ballast group such as a lipophilic group (oil-protected) and applying them in oil droplets to the film, or a hydrophilic group, or in a polymer layer such as a loadable latex layer with oil-protected couplers, in which case they are considered to be polymer-protected. The color couplers may be colorless and be chromogenic or be colored. Colored couplers are used to improve
2970-401: Is due to the statistics of grain activation: as the film becomes progressively more exposed, each incident photon is less likely to impact a still-unexposed grain, yielding the logarithmic behavior. A simple, idealized statistical model yields the equation density = 1 – ( 1 – k ) , where light is proportional to the number of photons hitting a unit area of film, k is the probability of
3069-940: Is either silver bromide or silver bromochloroiodide, or a combination of silver bromide, chloride and iodide. Silver iodobromide may be used as a silver halide. Silver halide crystals can be made in several shapes for use in photographic films. For example, AgBrCl hexagonal tabular grains can be used for color negative films, AgBr octahedral grains can be used for instant color photography films, AgBrl cubo-octahedral grains can be used for color reversal films, AgBr hexagonal tabular grains can be used for medical X-ray films, and AgBrCl cubic grains can be used for graphic arts films. In color films, each emulsion layer has silver halide crystals that are sensitized to one particular color (wavelength of light) vía sentizing dyes, to that they will be made sensitive to only one color of light, and not to others, since silver halide particles are intrinsically sensitive only to wavelengths below 450 nm (which
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3168-407: Is highly preferable for post-production, exhibition, and archival purposes because of its flexibility, strength, and stability. Its strength is sometimes also seen as a disadvantage, however, in that polyester-base films are so resistant to breakage that they are often more likely to break the film equipment should a jam, or extra tension, occur. Movie cameras therefore do not use this base for shooting
3267-433: Is recommended in quantities no greater than one frame without extensive safety precautions. The smoke produced by burning nitrate film is highly toxic, containing several poisonous gases and can become lethal if inhaled enough. Many nitrate films have been transferred in recent decades to safety stock, and original nitrate prints are generally stored separately to prevent a nitrate fire from destroying other non-nitrate films;
3366-557: Is safer than nitrate but not as strong as polyester bases, which may damage the camera rather than the film should a jam occur. Acetate can also be spliced with film cement, while polyester can only be spliced with tape or an ultrasonic splicer, so polyester is hard to edit . Acetate film does not burn under intense heat, but rather melts, causing a bubbling burn-out effect — this can be seen simulated in films such as Persona (1966), Two-Lane Blacktop (1971) , The Muppet Movie (1979) or Velvet Goldmine (1998). It can happen during
3465-474: Is used by photofinishing equipment during film processing. The second part is a barcode on the edge of the film ( see image below right ), used also during processing, which indicates the image film type, manufacturer, frame number and synchronizes the position of the frame. The third part of DX coding, known as the DX Camera Auto Sensing (CAS) code, consists of a series of 12 metal contacts on
3564-499: Is usually placed in close contact with phosphor screen(s) and/or thin lead-foil screen(s), the combination having a higher sensitivity to X-rays. Because film is sensitive to x-rays, its contents may be wiped by airport baggage scanners if the film has a speed higher than 800 ISO. This property is exploited in Film badge dosimeters . Film optimized for detecting X-rays and gamma rays is sometimes used for radiation dosimetry . Film has
3663-580: The ASA speed and the DIN speed in the format ASA/DIN. Using ISO convention film with an ASA speed of 400 would be labeled 400/27°. A fourth naming standard is GOST , developed by the Russian standards authority. See the film speed article for a table of conversions between ASA, DIN, and GOST film speeds. Common film speeds include ISO 25, 50, 64, 100, 160, 200, 400, 800 and 1600. Consumer print films are usually in
3762-624: The K-14 process , Kodacolor, Ektachrome , which is often processed using the E-6 process and Fujifilm Superia , which is processed using the C-41 process . The chemicals and the color dye couplers on the film may vary depending on the process used to develop the film. Film speed describes a film's threshold sensitivity to light. The international standard for rating film speed is the ISO scale, which combines both
3861-540: The Lumière Brothers introduced their Lumière Panchromatic plate, which was made sensitive, although very unequally, to all colors including red. New and improved sensitizing dyes were developed, and in 1902 the much more evenly color-sensitive Perchromo panchromatic plate was being sold by the German manufacturer Perutz . The commercial availability of highly panchromatic black-and-white emulsions also accelerated
3960-447: The infrared (IR) region of the spectrum . In black-and-white photographic film, there is usually one layer of silver halide crystals. When the exposed silver halide grains are developed, the silver halide crystals are converted to metallic silver, which blocks light and appears as the black part of the film negative . Color film has at least three sensitive layers, incorporating different combinations of sensitizing dyes. Typically
4059-482: The light sensitivity of photographic emulsions in 1876. Their work enabled the first quantitative measure of film speed to be devised. They developed H&D curves, which are specific for each film and paper. These curves plot the photographic density against the log of the exposure, to determine sensitivity or speed of the emulsion and enabling correct exposure. Early photographic plates and films were usefully sensitive only to blue, violet and ultraviolet light . As
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4158-871: The Blinding Light! in Vancouver, and the Robert Beck Memorial Cinema at Collective: Unconscious. Video transfers of Andy Warhol's footage have been shown at the Andy Warhol Museum in Pittsburgh, and at the San Francisco Lesbian & Gay Film Festival in 2001. In 1983, Polaroid introduced an "instant" transparency ( slide film ) system for still photography. Each roll of 35 mm film came with its own small packet of processing chemistry. After exposure,
4257-429: The ISO 100 to ISO 800 range. Some films, like Kodak's Technical Pan , are not ISO rated and therefore careful examination of the film's properties must be made by the photographer before exposure and development. ISO 25 film is very "slow", as it requires much more exposure to produce a usable image than "fast" ISO 800 film. Films of ISO 800 and greater are thus better suited to low-light situations and action shots (where
4356-474: The National Archives lost 12.6 million feet of newsreel footage. Because cellulose nitrate contains oxygen, nitrate fires are impossible to extinguish. The US Navy has produced an instructional movie about the safe handling and usage of nitrate films which includes footage of a full reel of nitrate film burning under water. The base is so flammable that intentionally igniting the film for test purposes
4455-432: The active dynamic range of most films, the density of the developed film is proportional to the logarithm of the total amount of light to which the film was exposed, so the transmission coefficient of the developed film is proportional to a power of the reciprocal of the brightness of the original exposure. The plot of the density of the film image against the log of the exposure is known as an H&D curve. This effect
4554-755: The back of the film base in triacetate film bases or in the front in PET film bases, below the emulsion stack. An anticurl layer and a separate antistatic layer may be present in thin high resolution films that have the antihalation layer below the emulsion. PET film bases are often dyed, specially because PET can serve as a light pipe; black and white film bases tend to have a higher level of dying applied to them. The film base needs to be transparent but with some density, perfectly flat, insensitive to light, chemically stable, resistant to tearing and strong enough to be handled manually and by camera mechanisms and film processing equipment, while being chemically resistant to moisture and
4653-439: The back of the film, it also serves to prevent scratching, as an antistatic measure due to its conductive carbon content, and as a lubricant to help transport the film through mechanisms. The antistatic property is necessary to prevent the film from getting fogged under low humidity, and mechanisms to avoid static are present in most if not all films. If applied on the back it is removed during film processing. If applied it may be on
4752-629: The basis of subsequent color film design, with the Agfa process initially adopted by Ferrania, Fuji and Konica and lasting until the late 70s/early 1980s in the West and 1990s in Eastern Europe. The process used dye-forming chemicals that terminated with sulfonic acid groups and had to be coated one layer at a time. It was a further innovation by Kodak, using dye-forming chemicals which terminated in 'fatty' tails which permitted multiple layers to coated at
4851-409: The blue and green sensitive layers and a yellow filter before the red sensitive layer; in this way each layer is made sensitive to only a certain color of light. The couplers need to be made resistant to diffusion (non-diffusible) so that they will not move between the layers of the film and thus cause incorrect color rendition as the couplers are specific to either cyan, magenta or yellow colors. This
4950-598: The blue part of the visible spectrum, producing unnatural-looking renditions of some colored subjects. This problem was resolved with the discovery that certain dyes, called sensitizing dyes, when adsorbed onto the silver halide crystals made them respond to other colors as well. First orthochromatic (sensitive to blue and green) and finally panchromatic (sensitive to all visible colors) films were developed. Panchromatic film renders all colors in shades of gray approximately matching their subjective brightness. By similar techniques, special-purpose films can be made sensitive to
5049-399: The blue-sensitive layer is on top, followed by a yellow filter layer to stop any remaining blue light from affecting the layers below. Next comes a green-and-blue sensitive layer, and a red-and-blue sensitive layer, which record the green and red images respectively. During development, the exposed silver halide crystals are converted to metallic silver, just as with black-and-white film. But in
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#17327810410165148-408: The camera would record, for example, the destruction of a pipe under pressure. This type of use was moderately price-insensitive, with the ability to get the images quickly (thus reducing wasted crew time) a very positive selling feature. The system was late to market and had to compete with upcoming Betamax and VHS videocassette-based systems, which in the pre- camcorder era of the late 1970s had
5247-495: The chemicals used during processing without losing strength, flexibility or changing in size. The subbing layer is essentially an adhesive that allows the subsequent layers to stick to the film base. The film base was initially made of highly flammable cellulose nitrate, which was replaced by cellulose acetate films , often cellulose triacetate film (safety film), which in turn was replaced in many films (such as all print films, most duplication films and some other specialty films) by
5346-479: The color filter mosaic layer absorbed most of the light passing through. The last films of this type were discontinued in the 1950s, but Polachrome "instant" slide film, introduced in 1983, temporarily revived the technology. "Color film" in the modern sense of a subtractive color product with a multi-layered emulsion was born with the introduction of Kodachrome for home movies in 1935 and as lengths of 35 mm film for still cameras in 1936; however, it required
5445-435: The color reproduction of film. The first coupler which is used in the blue layer remains colorless to allow all light to pass through, but the coupler used in the green layer is colored yellow, and the coupler used in the red layer is light pink. Yellow was chosen to block any remaining blue light from exposing the underlying green and red layers (since yellow can be made from green and red). Each layer should only be sensitive to
5544-411: The coupler forms a yellow dye; in the green sensitive layer the coupler forms a magenta dye, and in the red sensitive layer the coupler forms a cyan dye. Color films often have an UV blocking layer. Each emulsion layer in a color film may itself have three layers: a slow, medium and fast layer, to allow the film to capture higher contrast images. The color dye couplers are inside oil droplets dispersed in
5643-513: The dangers of the nitrate film base being known practically since its development, it was used in virtually all major motion pictures prior to 1952, when Kodak completed a four-year conversion program to the sole manufacturing of acetate base film stocks. Kodak began working with acetate "safety film" as early as 1909, and started selling it in 1910 for 22 mm film. Acetate has always been used with 8 mm and 16 mm formats, as they were originally created for amateur home movie usage, and generally
5742-467: The date, shutter speed and aperture setting are recorded on the negative directly as the film is exposed. The first known version of this process was patented in the United States in 1975, using half-silvered mirrors to direct the readout of a digital clock and mix it with the light rays coming through the main camera lens. Modern SLR cameras use an imprinter fixed to the back of the camera on
5841-412: The degradation progresses the film base becomes brittle and shrinks. In the literature of photography polyester is polyethylene terephthalate , which Kodak trade-named "ESTAR". Polyester is the most recent film base to have been developed. It was first used for specialized photography applications in 1955, but it was only in the 1990s that it became overwhelmingly popular for motion picture prints. It
5940-407: The disadvantages of much greater bulk and much higher initial hardware cost. However, a standard videocassette ran for at least an hour at the highest-quality speed, while a Polavision cartridge contained less than three minutes of film, at a far higher per-minute cost than the finest videocassette tape. It could not be erased and reused, or shown on a real television set with a larger screen, and there
6039-466: The dyes are instead formed by a long sequence of steps, limiting adoption among smaller film processing companies. Black and white films are very simple by comparison, only consisting of silver halide crystals suspended in a gelatin emulsion which sits on a film base with an antihalation back. Many films contain a top supercoat layer to protect the emulsion layers from damage. Some manufacturers manufacture their films with daylight, tungsten (named after
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#17327810410166138-502: The early 20th century. Although color photographs of good quality were being made by the 1890s, they required special equipment, separate and long exposures through three color filters , complex printing or display procedures, and highly specialized skills, so they were then exceedingly rare. The first practical and commercially successful color "film" was the Lumière Autochrome , a glass plate product introduced in 1907. It
6237-443: The emulsion around silver halide crystals, forming a silver halide grain. Here the oil droplets act as a surfactant , also protecting the couplers from chemical reactions with the silver halide and from the surrounding gelatin. During development, oxidized developer diffuses into the oil droplets and combines with the dye couplers to form dye clouds; the dye clouds only form around unexposed silver halide crystals. The fixer then removes
6336-445: The feed and take-up reels, and several fire extinguishers built into the projector and aimed at the projector's film gate with a trigger released if the film ignites. Nitrate film is classified as "dangerous goods", which requires licenses for storage and transportation. Nitrate film stock was used in every major film production before about 1951. Many silent films only survived because they were printed to 16 mm film , which did not use
6435-495: The film and its packet were loaded into a small hand-cranked machine called an "AutoProcessor". The time it required to produce a fully developed film ready for mounting varied from between two and five minutes, depending on the type of film. Polaroid produced several types of AutoProcess-compatible 35 mm film: Polaroid AutoProcess slides could be viewed or projected in the same way as 35 mm slides made with conventional films. Photographic film Photographic film
6534-432: The film backing plate. It uses a small LED display for illumination and optics to focus the light onto a specific part of the film. The LED display is exposed on the negative at the same time the picture is taken. Digital cameras can often encode all the information in the image file itself. The Exif format is the most commonly used format. In the 1980s, Kodak developed DX Encoding (from Digital indeX), or DX coding ,
6633-428: The film cassette, which beginning with cameras manufactured after 1985 could detect the type of film, number of exposures and ISO of the film, and use that information to automatically adjust the camera settings for the speed of the film. Source: e.g., Kodak "Advantix", different aspect ratios possible, data recorded on magnetic strip, processed film remains in cartridge The earliest practical photographic process
6732-625: The film's sensitivity to light – or speed – the film there will have no appreciable image density, and will appear on the print as a featureless black. Some photographers use their knowledge of these limits to determine the optimum exposure for a photograph; for one example, see the Zone System . Most automatic cameras instead try to achieve a particular average density. Color films can have many layers. The film base can have an antihalation layer applied to it or be dyed. This layer prevents light from reflecting from within
6831-575: The film, increasing image quality. This also can make films exposable on only one side, as it prevents exposure from behind the film. This layer is bleached after development to make it clear, thus making the film transparent. The antihalation layer, besides having a black colloidal silver sol pigment for absorbing light, can also have two UV absorbents to improve lightfastness of the developed image, an oxidized developer scavenger, dyes for compensating for optical density during printing, solvents, gelatin and disodium salt of 3,5- disulfocatechol. If applied to
6930-420: The final print. Usually those areas will be considered overexposed and will appear as featureless white on the print. Some subject matter is tolerant of very heavy exposure. For example, sources of brilliant light, such as a light bulb or the sun, generally appear best as a featureless white on the print. Likewise, if part of an image receives less than the beginning threshold level of exposure, which depends upon
7029-421: The gas they release also affects the emulsion of safety film. Usually nitrate collections are even split up into several different fireproof rooms to minimize damage to an entire collection should a fire occur in one part. It is normal for a theater today to pass rigorous safety standards and precautions before being certified to run nitrate films; this includes a fireproof projection booth, fire chambers surrounding
7128-415: The infrared focal point must be compensated for. Exposure and focusing are difficult when using UV or IR film with a camera and lens designed for visible light. The ISO standard for film speed only applies to visible light, so visual-spectrum light meters are nearly useless. Film manufacturers can supply suggested equivalent film speeds under different conditions, and recommend heavy bracketing (e.g., "with
7227-501: The laboratory, but in 1883 the first commercially dye-sensitized plates appeared on the market. These early products, described as isochromatic or orthochromatic depending on the manufacturer, made possible a more accurate rendering of colored subject matter into a black-and-white image. Because they were still disproportionately sensitive to blue, the use of a yellow filter and a consequently longer exposure time were required to take full advantage of their extended sensitivity. In 1894,
7326-410: The light loss caused by the filtering layer, which allows only red, green or blue light to pass through any given point on it, the film had relatively low light sensitivity (40 ASA ) and the developed footage has an overall veil that appears to be a neutral gray. The system features a standalone tabletop viewer designed to minimize the problems inherent in projecting such dense film. Somewhat resembling
7425-408: The long exposures required by astrophotography. Lith films used in the printing industry. In particular when exposed via a ruled-glass screen or contact-screen, halftone images suitable for printing could be generated. Some film cameras have the ability to read metadata from the film canister or encode metadata on film negatives. Negative imprinting is a feature of some film cameras, in which
7524-415: The original camera negative, as it is vastly preferable, and less costly in time and money, for the film to break instead of the camera. In addition, cameras require a lap-spliceable triacetate base to allow the use of all of the negative stock. PET film base can be ultrasonically spliced or by melting and joining the ends of two films together. There are several factors that can aid in identification of
7623-442: The physics of silver grain activation (which sets a minimum amount of light required to expose a single grain) and by the statistics of random grain activation by photons. The film requires a minimum amount of light before it begins to expose, and then responds by progressive darkening over a wide dynamic range of exposure until all of the grains are exposed, and the film achieves (after development) its maximum optical density. Over
7722-405: The printing process. The concentration of dyes or silver halide crystals remaining on the film after development is referred to as optical density , or simply density ; the optical density is proportional to the logarithm of the optical transmission coefficient of the developed film. A dark image on the negative is of higher density than a more transparent image. Most films are affected by
7821-565: The process is too slow and incomplete to be of any practical use. Instead, a very short exposure to the image formed by a camera lens is used to produce only a very slight chemical change, proportional to the amount of light absorbed by each crystal. This creates an invisible latent image in the emulsion, which can be chemically developed into a visible photograph . In addition to visible light, all films are sensitive to ultraviolet light, X-rays , gamma rays , and high-energy particles . Unmodified silver halide crystals are sensitive only to
7920-491: The progress of practical color photography, which requires good sensitivity to all the colors of the spectrum for the red, green and blue channels of color information to all be captured with reasonable exposure times. However, all of these were glass-based plate products. Panchromatic emulsions on a film base were not commercially available until the 1910s and did not come into general use until much later. Many photographers who did their own darkroom work preferred to go without
8019-517: The resulting stampede. An accidental fire caused by the film jamming in the gate formed a significant plot point in the movie Cinema Paradiso (1988). The year 1978 was particularly devastating for film archives when both the United States National Archives and Records Administration and George Eastman House had their nitrate film vaults auto-ignite. Eastman House lost the original camera negatives for 329 films, while
8118-477: The same time in a single pass, reducing production time and cost that later became universally adopted along with the Kodak C-41 process. Film base A film base is a transparent substrate which acts as a support medium for the photosensitive emulsion that lies atop it. Despite the numerous layers and coatings associated with the emulsion layer, the base generally accounts for the vast majority of
8217-414: The seeming luxury of sensitivity to red – a rare color in nature and uncommon even in human-made objects – rather than be forced to abandon the traditional red darkroom safelight and process their exposed film in complete darkness. Kodak's popular Verichrome black-and-white snapshot film, introduced in 1931, remained a red-insensitive orthochromatic product until 1956, when it
8316-470: The short exposure time limits the total light received). The benefit of slower film is that it usually has finer grain and better color rendition than fast film. Professional photographers of static subjects such as portraits or landscapes usually seek these qualities, and therefore require a tripod to stabilize the camera for a longer exposure. A professional photographing subjects such as rapidly moving sports or in low-light conditions will inevitably choose
8415-416: The silver halide crystals leaving only the dye clouds: this means that developed color films may not contain silver while undeveloped films do contain silver; this also means that the fixer can start to contain silver which can then be removed through electrolysis. Color films also contain light filters to filter out certain colors as the light passes through the film: often there is a blue light filter between
8514-650: The silver is converted back to silver halide crystals in the bleach step . It is removed from the film during the process of fixing the image on the film with a solution of ammonium thiosulfate or sodium thiosulfate (hypo or fixer). Fixing leaves behind only the formed color dyes, which combine to make up the colored visible image. Later color films, like Kodacolor II , have as many as 12 emulsion layers, with upwards of 20 different chemicals in each layer. Photographic film and film stock tend to be similar in composition and speed, but often not in other parameters such as frame size and length. Silver halide photographic paper
8613-519: The speed of the film; since films contain real silver (as silver halide), faster films with larger crystals are more expensive and potentially subject to variations in the price of silver metal. Also, faster films have more grain, since the grains (crystals) are larger. Each crystal is often 0.2 to 2 microns in size; in color films, the dye clouds that form around the silver halide crystals are often 25 microns across. The crystals can be shaped as cubes, flat rectangles, tetradecadedra, or be flat and resemble
8712-444: The thickness of any given film stock . Since the late 19th century, there have been three major types of film base in use: nitrate (until about 1951), acetate , and polyester . In the literature of photography "nitrate" is used as a synonym for the chemical nitrocellulose . It is also referred to as "cellulose nitrate". Nitrocellulose is guncotton , the first replacement propellant for gun powder in firearms. Film stock with
8811-437: The tungsten filament of incandescent and halogen lamps) or fluorescent lighting in mind, recommending the use of lens filters, light meters and test shots in some situations to maintain color balance, or by recommending the division of the ISO value of the film by the distance of the subject from the camera to get an appropriate f-number value to be set in the lens. Examples of Color films are Kodachrome , often processed using
8910-475: The visibility of the clouds, by manually retouching their negatives to adjust problematic tonal values, and by heavily powdering the faces of their portrait sitters. In 1873, Hermann Wilhelm Vogel discovered that the spectral sensitivity could be extended to green and yellow light by adding very small quantities of certain dyes to the emulsion. The instability of early sensitizing dyes and their tendency to rapidly cause fogging initially confined their use to
9009-411: Was expensive and not sensitive enough for hand-held "snapshot" use. Film-based versions were introduced in the early 1930s and the sensitivity was later improved. These were "mosaic screen" additive color products, which used a simple layer of black-and-white emulsion in combination with a layer of microscopically small color filter elements. The resulting transparencies or "slides" were very dark because
9108-412: Was no sound. Polavision proved to be an expensive failure, and most of the manufactured equipment was sold off in 1979 as a job lot at a loss of $ 68.5 million. In the wake of those losses, Polaroid chairman and founder Edwin H. Land resigned the chief executive position in 1980 and left the company two years later. Former Polaroid freelancer Paul Giambarba remarked, I tried using the product but it
9207-413: Was obviously a turkey compared to anything I was using that Kodak offered [...] Instant movie film was an engineering achievement but it's precisely what separated Polaroid techies from Polaroid pragmatists. There just weren't enough customers out there on whom to work the magic. Polavision film is rarely screened in public, but it has happened, at such venues as Anthology Film Archives (in 1998 and 2007),
9306-438: Was of better optical quality than early transparent plastics and was, at first, less expensive. Glass plates continued to be used long after the introduction of film, and were used for astrophotography and electron micrography until the early 2000s, when they were supplanted by digital recording methods. Ilford continues to manufacture glass plates for special scientific applications. The first flexible photographic roll film
9405-408: Was removed from the Polavision camera, ready for viewing in only a few minutes. The Polavision cartridge called Photo tape cassette is a small rectangular box containing the film reels and a prism letting in light for projection through a film gate . The film format is similar to the super 8 mm format, but without the Polavision tabletop viewer the only way a Polavision film can be shown
9504-448: Was replaced by Verichrome Pan. Amateur darkroom enthusiasts then had to handle the undeveloped film by the sense of touch alone. Experiments with color photography began almost as early as photography itself, but the three-color principle underlying all practical processes was not set forth until 1855, not demonstrated until 1861, and not generally accepted as "real" color photography until it had become an undeniable commercial reality in
9603-464: Was sold by George Eastman in 1885, but this original "film" was actually a coating on a paper base. As part of the processing, the image-bearing layer was stripped from the paper and attached to a sheet of hardened clear gelatin. The first transparent plastic roll film followed in 1889. It was made from highly flammable cellulose nitrate film . Although cellulose acetate or " safety film " had been introduced by Kodak in 1908, at first it found only
9702-420: Was the daguerreotype ; it was introduced in 1839 and did not use film. The light-sensitive chemicals were formed on the surface of a silver-plated copper sheet. The calotype process produced paper negatives. Beginning in the 1850s, thin glass plates coated with photographic emulsion became the standard material for use in the camera. Although fragile and relatively heavy, the glass used for photographic plates
9801-448: Was used for most sub-35 mm formats to minimize risk to the general public. Several formats, such as 17.5 mm, which were often re-slit from 35 mm, were nitrate, however. One of Kodak's reasons for choosing 16 mm instead of 17.5 mm for a standard amateur format width was specifically to prevent nitrate re-slits from being used in home movies. All motion picture camera negatives are now shot on acetate film because it
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