ABSTRACT
Most small- and medium-format cameras lack the features of displacement and rotational movements unless a special lens mount adapter is used incorporating a bellows or a ball and socket joint arrangement to provide limited movements, and then only with long focus lenses. More efficient use of the format area is given by use of a so-called perspective control (PC) lens. Both PC and tilt and shift lenses are supplied in modified lens barrels with supplementary controls to shift or tilt the optical unit relative to the lens mount throat using a rack and pinion arrangement. Shift cameras using medium and panoramic formats use wide-angle lenses for large formats to provide both angular coverage and extreme shift in one, vertical direction for perspective control. The requirements of film or slide projection, especially for registered, multi-projector images in slidetape and multi-media presentations, need projection lenses capable of shift movements.
