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Instant film is a type of photographic film introduced by Polaroid to be used in an instant camera (and, with accessory hardware, with many professional film cameras). The film contains the chemicals needed for developing and fixing the photo, and the instant camera exposes and initiates the developing process after a photograph has been taken. In earlier Polaroid instant cameras the film is pulled through rollers which breaks open a pod containing a reagent that is spread between the exposed negative and receiving positive sheet. This film sandwich develops for a predetermined time, depending on film type and ambient temperature, after which the positive sheet is peeled away from the negative to reveal the developed photo. In 1972, Polaroid introduced integral film, which incorporated timing and receiving layers to automatically develop and fix the photo without any intervention from the photographer. Instant film is available in sizes from 24 mm × 36 mm (similar to 135 film) up to 50.8 cm × 61 cm size, with the most popular film sizes for consumer snapshots being approximately 83mm × 108mm (the image itself is smaller as it is surrounded by a border). Early instant film was distributed on rolls, but later and current films are supplied in packs of 8 or 10 sheets, and single sheet films for use in large format cameras with a compatible back. Integral film packs may contain a flat "Polapulse" electrical battery, which powers systems in the camera, including exposure and focusing mechanisms, electronic flash, and a film ejection motor. The inclusion of the battery within the film pack ensures that a fresh battery is available with each new pack of film. Though the quality of integral instant film is not as good as conventional film, peel apart black and white film, and to a lesser extent color film approached the quality of traditional film types. Instant film was used where it was undesirable to have to wait for a roll of conventional film to be finished and processed, e.g., documenting evidence in law enforcement, in health care and scientific applications, and producing photographs for passports and other identity documents, and simply for snapshots to be seen immediately. Some photographers use instant film for test shots, to see how a subject or setup looks before using conventional film for the final exposure. Instant film is also used by artists to achieve effects that are impossible to accomplish with traditional photography, by manipulating the emulsion during the developing process, or separating the image emulsion from the film base. Instant film has been supplanted for most purposes by digital photography, which allows the result to be viewed immediately on a display screen or printed with dye sublimation, inkjet, or laser home or professional printers. Instant film is notable for having had a wider range of film speeds available than other negative films of the same era: instant film has been produced with ISO 4 to ISO 20,000. Current instant film formats typically have an ISO between 80 and 3000. two companies manufacture instant film: Fuji (Peel Apart and Instax integral film) and The Impossible Project for older Polaroid cameras (600, SX-70, Spectra and 8x10). ==How it works== Instant positive film (which produced a print) uses diffusion transfer to move the dyes from the negative to the positive via a reagent. The process varies according to the film type. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Instant film」の詳細全文を読む スポンサード リンク
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