Large-format slide projector
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A large-format slide projector (also often called "large-format projector" or "large-image projector") is a kind of slide projector for large image projection which has a very powerful light source (up to 12 thousand watts using arc lamps). Therefore it is necessary to use a large slide format to protect the slide material from overheating during the projection process (even when the light is filtered to only visible light and the slide is cooled with strong slide cooling fans). Slide formats of 18 × 18 cm (7.1 × 7.1") or 24 × 24 cm (9.4 × 9.4").
On the other hand this formats are so large that it is possible to project slides painted with heat resistant translucent colours as a special kind of art (projection art). The light output of the projector is so enormous that it is possible to cover whole buildings with an artistic cover of light.
History
The first large-format slide projectors were built in the middle of the 20th century as background projectors for theaters and opera houses. The artists Professor Schneider-Siemmsen,[1] Professor Svoboda and Herbert von Karajan used the large format slide projectors as stage projectors in their artwork. In good cooperation with the technician Ing. Ludwig Pani,[2] they realized the first large format projections as an integrated part of their artwork.