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A tintype, also known as a melainotype or ferrotype, is a photograph made by creating a direct positive on a thin sheet of metal coated with a dark lacquer or enamel and used as the support for the photographic emulsion. Tintypes enjoyed their widest use during the 1860s and 1870s, but lesser use of the medium persisted into the early 20th century and it has been revived as a novelty in the 21st. Tintype portraits were at first usually made in a formal photographic studio, like daguerreotypes and other early types of photographs, but later they were most commonly made by photographers working in booths or the open air at fairs and carnivals, as well as by itinerant sidewalk photographers. Because the lacquered iron support (there is no actual tin used) was resilient and did not need drying, a tintype could be developed and fixed and handed to the customer only a few minutes after the picture had been taken. The tintype photograph saw more uses and captured a wider variety of settings and subjects than any other photographic type. It was introduced while the daguerreotype was still popular, though its primary competition would have been the ambrotype. The tintype saw the Civil War come and go, documenting the individual soldier and horrific battle scenes. It captured scenes from the Wild West, as it was easy to produce by itinerant photographers working out of covered wagons. It began losing artistic and commercial ground to higher quality albumen prints on paper in the mid-1860s, yet survived for well over another 40 years, living mostly as a carnival novelty. 〔http://www.phototree.com/id_tin.htm〕 The tintype's immediate predecessor, the ambrotype, was done by the same process of using a sheet of glass as the support. The glass was either of a dark color or provided with a black backing so that, as with a tintype, the underexposed negative image in the emulsion appeared as a positive. Tintypes were sturdy and did not require mounting in a protective hard case like ambrotypes and daguerreotypes. ==Technical details== There are two historic tintype processes: wet and dry. In the wet process, a collodion emulsion containing suspended silver halide crystals had to be formed on the plate just before it was exposed in the camera while still wet. Chemical treatment then reduced the crystals to microscopic particles of metallic silver in proportion to the intensity and duration of their exposure to light, resulting in a visible image. The later and more convenient dry process was similar but used a gelatin emulsion which could be applied to the plate long before use and exposed in the camera dry. In both processes, a very underexposed negative image was produced in the emulsion. Its densest areas, corresponding to the lightest parts of the subject, appeared gray by reflected light. The areas with the least amount of silver, corresponding to the darkest areas of the subject, were essentially transparent and appeared black when seen against the dark background provided by the lacquer. The image as a whole therefore appeared to be a dull-toned positive.〔("What Do You Know About Tintypes?" ), Ohio Historical Society Collections Blog, 2011-08-05.〕 This ability to employ underexposed images allowed shorter exposure times to be used, a great advantage in portraiture. To obtain as light-toned an image as possible, potassium cyanide, a very dangerous and powerful deadly poison, was normally employed as the photographic fixer. It was perhaps the most acutely hazardous of all the several highly toxic chemicals originally used in this and many other early photographic processes. One unusual piece of tintype equipment was a twelve-lensed camera that could make a dozen "gem" portraits with one exposure, developed in 1858.〔 Portrait sizes ranged from gem-size to . From about 1865 to 1910, the most popular size, called "Bon-ton", ranged from to .〔 Each tintype is usually a camera original, so the image is usually a mirror image, reversed left to right from reality. Sometimes the camera was fitted with a mirror or right-angle prism so that the end result would be right-reading. 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「tintype」の詳細全文を読む スポンサード リンク
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