Difference between revisions of "Projector"
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| − | A '''projector''' is a device that focuses an enlarged image from a piece of film (almost always a ''positive'' image, often mounted as an individual 'slide') onto a screen for viewing. It is very similar in principle to an [[enlarger]], comprising a light source, film holder, and a lens with a focusing mechanism; however, the arrangement of these components is somewhat different because images are usually projected horizontally, and because of the different scale usually required; it is usual to project images for viewing at large degrees of enlargement, and the screen is likely to be a long distance from the projector. In addition to the basic components listed above, a projector is likely to have a mechanism for changing from one slide to another, and a cooling fan to protect the film from the lamp's heat. | + | A '''projector''' is a device that focuses an enlarged image, usually from a piece of film (almost always a ''positive'' image, often mounted as an individual 'slide') onto a screen for viewing. It is very similar in principle to an [[enlarger]], comprising a light source, film holder, and a lens with a focusing mechanism; however, the arrangement of these components is somewhat different because images are usually projected horizontally, and because of the different scale usually required; it is usual to project images for viewing at large degrees of enlargement, and the screen is likely to be a long distance from the projector. In addition to the basic components listed above, a projector is likely to have a mechanism for changing from one slide to another, and a cooling fan to protect the film from the lamp's heat. |
A projector is also the corresponding device for showing cine film. | A projector is also the corresponding device for showing cine film. | ||
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| + | Projectors for transparent originals as described above were previously called '''diascopes''' (and earlier '''magic lanterns'''). Devices to project an image of an opaque original (typically a printed picture) were called '''episcopes'''; both functions were often combined in an '''epidiascope'''. | ||
Revision as of 10:29, 27 November 2012
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| 35 mm slide projector by the British Aldis company. image by S. Erik Bjernhage (Image rights) |
A projector is a device that focuses an enlarged image, usually from a piece of film (almost always a positive image, often mounted as an individual 'slide') onto a screen for viewing. It is very similar in principle to an enlarger, comprising a light source, film holder, and a lens with a focusing mechanism; however, the arrangement of these components is somewhat different because images are usually projected horizontally, and because of the different scale usually required; it is usual to project images for viewing at large degrees of enlargement, and the screen is likely to be a long distance from the projector. In addition to the basic components listed above, a projector is likely to have a mechanism for changing from one slide to another, and a cooling fan to protect the film from the lamp's heat.
A projector is also the corresponding device for showing cine film.
Projectors for transparent originals as described above were previously called diascopes (and earlier magic lanterns). Devices to project an image of an opaque original (typically a printed picture) were called episcopes; both functions were often combined in an epidiascope.
