The magic lantern , also known by its Latin name lanterna magica , was an early type of image projector that used picturesโpaintings, prints, or photographs โon transparent plates usually made of glass , one or more lenses , and a light source.
Because a single lens inverts an image projected through it as in the phenomenon which inverts the image of a camera obscura , slides were inserted upside down in the magic lantern, rendering the projected image correctly oriented. It was mostly developed in the 17th century and commonly used for entertainment purposes.
(mh=HH6Bu2Aed84CqWtU)11.jpg "Teen girls Augsburg")
It was increasingly used for education during the 19th century. Since the late 19th century, smaller versions were also mass-produced as toys. The magic lantern was in wide use from the 18th century until the midth century when it was superseded by a compact version that could hold many 35 mm photographic slides: the slide projector.
The magic lantern used a concave mirror behind a light source to direct the light through a small rectangular sheet of glassโa "lantern slide" that bore the imageโand onward into a lens at the front of the apparatus.
The lens adjusted to focus the plane of the slide at the distance of the projection screen, which could be simply a white wall, and it therefore formed an enlarged image of the slide on the screen. Biunial lanterns, with two objectives, became common during the 19th century and enabled a smooth and easy change of pictures. Stereopticons added more powerful light sources to optimize the projection of photographic slides.
