Fisheye projection lens system for 35mm motion pictures

摘要

A 180° high resolution fisheye projection lens suitable for projecting images onto a hemispherical dome, such as a planetarium dome, includes a nine-element projection lens and a six-element relay lens. The relay lens serves to increase the distance between the film plane and the lens and eliminates the need for modifying the projector to provide clearance between the lens and the projector shutter mechanism. In addition, the relay lens may be modified to make the fisheye lens compatible with various film sizes without modifying the fisheye lens. A focused iris is used to mask portions of the projected image, and a nonuniformly acting fader is used to reduce back scatter and to stop down the lens to adjust the brightness of the projected image.