Projector

Glossary Terms

Kodak Ektapro 500 with carousel magazine. image by nickant44 (Image rights)	Slide projector Model C by Waterworth of Hobart. image by Dirk HR Spennemann (Image rights)
Bakelite-bodied Filmosto Primascop, about 1952. image by Sven Hafner (Image rights)	Pentacon H50 projector. image by Sven Hafner (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', though some can also project from a film strip or roll) 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.

The corresponding device for showing cine film is also called a projector.

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) are called episcopes; both functions were often combined in an epidiascope.

An overhead projector is essentially a light-box with a lens-and-mirror unit mounted above it, designed for projection of large (typically about A4) transparencies, usually of text and graphics for educational or business presentations. Some of these can also be arranged as episcopes.

Projectors for film originals have largely been made obsolete by the use of digital cameras . Braun Photo-Technik still lists three slide projector models as current products (as of November 2016); Projectors made by the Reflecta company were still offered for sale by some online retailers (again, in November 2016) but are not listed as current products by the manufacturer. Both Braun and Reflecta still offer episcopes.

Projectors are also made (since the 1990s) to display images from digital files.

• Overview Slide Projectors

Links

• The Dagestad Collection of magic lanterns and early cine projectors, at Flickr
• LUCERNA database on magic lanterns