A slide is a specially mounted individual transparency intended for projection onto a screen using a slide projector. This allows the photograph to be viewed by a large audience at once. The most common form is the 35mm slide, with the image framed in a 2×2 inch cardboard or plastic mount. Some specialized labs produce photographic slides from digital camera images in formats such as JPEG, from computer-generated presentation graphics, and from a wide variety of physical source material such as fingerprints, microscopic sections, paper documents, astronomical images, etc.
Reversal film is sometimes used as motion picture film, mostly in the 16mm, Super8 and 8mm"cine" formats, to yield a positive image on the camera original. This avoids the expense of using negative film, which requires additional film and processing to create a positive film print for projection.
History
Additive method
The earliest practical and commercially successful color photography reversal process was the LumièreAutochrome, introduced in 1907. This was an additive method, using a panchromatic emulsion coated on a thin glass plate previously coated with a layer of dyed potato starch grains. Autochrome plates were discontinued in the 1930s,[2] after the introduction of Lumière Filmcolor in sheet film and Lumicolor in roll film sizes. Also using the additive principle and reversal processing were the Agfa color screen plates and films and Dufaycolor film, all of which were discontinued by 1961.[3]
In late 1936, Agfacolor Neu was launched, Agfa having overcome earlier difficulties with color sensitivity problems. This film had the dye couplers incorporated into the emulsion, making processing simpler than for Kodachrome.[3]
Early color negative film had many shortcomings, including the high cost of the film, processing and printing, the mediocre color quality, rapid fading and discoloration of highlights[5] of some types of print that became noticeable after several years. Amateurs who owned projection equipment used reversal films extensively because the cost of projection equipment and slide film was offset by not having to pay for prints. Eventually, print quality improved and prices decreased, and, by the 1970s, color negative film and color prints had largely displaced slides as the primary method of amateur photography.
Until about 1995, color transparency was preferred for publication because of the films' higher contrast and resolution, and was widely used in commercial and advertising photography, reportage, sports, stock and nature photography. Digital media gradually replaced transparency film. [6][pageneeded]
Film types
All color reversal film sold today is developed with the E-6 process. The non-substantive Kodachrome films, the last of which was discontinued in 2009, were processed with the K-14 process.[7]
Polaroid produced an instant slide film called Polachrome. It was packaged in cassettes like normal 35mm film. A separate processing unit was used to develop it after exposure.
Picture of a boat taken on Fomapan R 100 black-and-white reversal film
Black-and-white transparencies can be made directly with some modern black-and-white films, which normally yield negatives. The negative image is developed but not fixed. The negative image is removed by bleaching with a solution of potassium permanganate or potassium dichromate in dilute sulfuric acid, which is removed by washing and a clearing bath containing sodium metabisulfite or potassium metabisulfite. The remaining silver halide salts are re-exposed to light, developed and fixed, and the film is washed and dried.[8]
Black-and-white transparencies were once popular for presentation of lecture materials using 3¼"×4" (3¼" square in the UK) glass-mounted slides. Such positive black-and-white projection is now rarely done,[citation needed] except in motion pictures. Even where black-and-white positives are currently used, the process to create them typically uses an internegative with standard processing instead of a chemical reversal process.
Black-and-white reversal films are less common than color reversal films.
Agfa-Gevaert discontinued its Agfa Scala 200x Professional black-and-white reversal film. This could be developed with their proprietary Scala process.
The Adox company released Scala 160 In 2017 , A black and white reversal film based on Agfa's discontinued Scala.
The Foma company of the Czech Republic produces one of only remaining dedicated black-and-white reversal film for 35mm stills, Fomapan R 100, which is also available in movie film formats.[9][10]
Kodak & Foma currently produce kits for reversal processing.
Kodak formerly offered a kit ("Direct Positive Film Developing Outfit") for reversal processing of its now-discontinued Panatomic X film, which doubled the effective film speed from 32 to 64. The bleaching bath used potassium dichromate and sodium bisulfate; the redeveloper was a fogging developer, and so unstable that its shelf-life after mixing was only slightly longer than the amount of time needed to process a single roll. This was replaced with a "T-Max Direct Positive Film Developing Outfit",[11] which uses potassium permanganate and sulfuric acid in the bleach.[12] In this kit, the fogging redeveloper is stable, but the bleach is not, with a shelf-life, once mixed, of no more than two weeks.
dr5 Chrome process, which produces black-and-white transparencies from most traditional halide (i.e., non-chromogenic) black-and-white negative films.
Kodak Tri-X Reversal Film 7266 and Kodak Plus-X Reversal Film 7265 are black-and-white reversal films used for movie-making.[13][14]
Ilford has published a reversal process applicable to all current B&W emulsions, but recommended for Pan F+, FP4+, and Delta 100.[8]
Finished transparencies are most frequently displayed by projection. Some projectors use a sliding mechanism to manually pull the transparency out of the side of the machine, where it is replaced by the next image. Modern, advanced projectors typically use a carousel that holds a large number of slides; a mechanism automatically pulls a single slide from the carousel and places it in front of the lamp. Small externally lit or battery-powered magnifying viewers are available.
In traditional newsrooms and magazine offices slides were viewed using a lightbox and a loupe, which allowed rapid side by side comparison of similar images.
Slide copier
A slide copier is a simple optical device that can be fastened to the lens mount of a camera to enable slide duplicates to be made. Whilst these devices were formerly used to make duplicates on to slide film, they are often now used in conjunction with digital cameras to digitize images from film-based transparencies. This method usually gives better resolution than using attachments for digital A4 flat-bed scanners.
The devices are typically about 30cm long, and screw into an intermediate 't-mount' attached to the camera. The lens in the copier does not need to be complex, because the systems are usually stopped down to small fnumbers (e.g. for the Makinon Zoom Unit, f/16 at 1:1 magnification, falling to f/22 at 3:1 magnification), and the object and image distances are similar, so that many aberrations are minimized.
Gallery
Slide viewer
Slide viewer
Slide archive box
Slide frame 6×6cm
Slide frames 6×6 centimeters (2.4in)
A type 120 reversal film from the mid-1950s: the Italian Ferraniacolor
Slide frames, 1940 (metal or card) to 1985 (plastic)
Agfacolor slide dated 1939
Agfacolor slide dated 1942
A US soldier poses with North Korean soldiers in this Kodachrome slide from 1956
A positive image in a slide from 2004
The typical high-contrast appearance of a Fuji Velvia slide image
↑ Various print and online sources offer discontinuation dates ranging from 1932 to 1938.
1 2 A. L. M. Sowerby, ed. (1961). Dictionary of Photography: A Reference Book for Amateur and Professional Photographers (19th Ed.). London: Iliffe Books Ltd. pp.126–132.
Film stock is an analog medium that is used for recording motion pictures or animation. It is recorded on by a movie camera, developed, edited, and projected onto a screen using a movie projector. It is a strip or sheet of transparent plastic 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. The emulsion will gradually darken if left exposed to light, but 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 X-rays and high-energy particles. Most are at least slightly sensitive to invisible ultraviolet (UV) light. Some special-purpose films are sensitive into the infrared (IR) region of the spectrum.
Super 8 mm film is a motion-picture film format released in 1965 by Eastman Kodak as an improvement over the older "Double" or "Regular" 8 mm home movie format.
The following list comprises significant milestones in the development of photography technology.
110 is a cartridge-based film format used in still photography. It was introduced by Kodak in 1972. 110 is essentially a miniaturized version of Kodak's earlier 126 film format. Each frame is 13 mm × 17 mm, with one registration hole. Cartridges with 12, 20, or 24 frames are available on-line. Production variations sometimes have allowed for an additional image.
Kodachrome is the brand name for a color reversal film introduced by Eastman Kodak in 1935. It was one of the first successful color materials and was used for both cinematography and still photography. For many years, Kodachrome was widely used for professional color photography, especially for images intended for publication in print media.
The E-6 process is a chromogenic photographic process for developing Ektachrome, Fujichrome and other color reversal photographic film.
In the processing of photographic films, plates or papers, the photographic developer is one or more chemicals that convert the latent image to a visible image. Developing agents achieve this conversion by reducing the silver halides, which are pale-colored, into silver metal, which is black when in the form of fine particles. The conversion occurs within the gelatine matrix. The special feature of photography is that the developer acts more quickly on those particles of silver halide that have been exposed to light. When left in developer, all the silver halides will eventually be reduced and turn black. Generally, the longer a developer is allowed to work, the darker the image.
Agfacolor was the name of a series of color film products made by Agfa of Germany. The first Agfacolor, introduced in 1932, was a film-based version of their Agfa-Farbenplatte, a "screen plate" product similar to the French Autochrome. In late 1936, Agfa introduced Agfacolor Neu, a pioneering color film of the general type still in use today. The new Agfacolor was originally a reversal film used for making "slides", home movies and short documentaries. By 1939, it had also been adapted into a negative film and a print film for use by the German motion picture industry. After World War II, the Agfacolor brand was applied to several varieties of color negative film for still photography, in which the negatives were used to make color prints on paper. The reversal film was then marketed as Agfachrome. These films use Color Developing Agent 1 in their color developer.
Ektachrome is a brand name owned by Kodak for a range of transparency, still and motion picture films previously available in many formats, including 35 mm and sheet sizes to 11 × 14 inch size. Ektachrome has a distinctive look that became familiar to many readers of National Geographic, which used it extensively for color photographs for decades in settings where Kodachrome was too slow. In terms of reciprocity characteristics, Ektachrome is stable at shutter speeds between ten seconds and 1/10,000 of a second.
The E-4 process is a now outdated process for developing color reversal (transparency) photographic film, which was introduced in 1966.
Ansco was the brand name of a photographic company based in Binghamton, New York, which produced photographic films, papers and cameras from the mid-19th century until the 1980s.
A Super 8mm camera is a motion picture camera specifically manufactured to use the Super 8mm motion picture format. Super 8mm film cameras were first manufactured in 1965 by Kodak for their newly introduced amateur film format, which replaced the Standard 8 mm film format. Manufacture continued until the rise in popularity of video cameras in the mid-1970s. In 2014 the first new Super 8mm camera in 30 years was introduced by the Danish company Logmar Camera Solutions. Most other cameras readily available are from the 1960s through the 1980s.
A chromogenic print, also known as a C-print or C-type print, a silver halide print, or a dye coupler print, is a photographic print made from a color negative, transparency or digital image, and developed using a chromogenic process. They are composed of three layers of gelatin, each containing an emulsion of silver halide, which is used as a light-sensitive material, and a different dye coupler of subtractive color which together, when developed, form a full-color image.
Color motion picture film refers both to unexposed color photographic film in a format suitable for use in a motion picture camera, and to finished motion picture film, ready for use in a projector, which bears images in color.
Analog photography, also known as film photography, is a term usually applied to photography that uses chemical processes to capture an image, typically on paper, film or a hard plate. These processes were the only methods available to photographers for more than a century prior to the invention of digital photography, which uses electronic sensors to record images to digital media. Analog electronic photography was sometimes used in the late 20th century but soon died out.
In still photography, Kodak's Kodacolor brand has been associated with various color negative films since 1942. Kodak claims that Kodacolor was "the world's first true color negative film". More accurately, it was the first color negative film intended for making paper prints: in 1939, Agfa had introduced a 35 mm Agfacolor negative film for use by the German motion picture industry, in which the negative was used only for making positive projection prints on 35 mm film. There have been several varieties of Kodacolor negative film, including Kodacolor-X, Kodacolor VR and Kodacolor Gold.
Photographic film 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.
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