International projectionist (Oct 1931-Sept 1933)

FIG. 2. BEAM DIRECTION IN NEW PROJECTOR a — parabolic mirror; b, c, e — lenses; d — tilting mirror; f — prism; g — film; h — adjusting mirror; i — diapositive (slide), mirror; i, k, I — projection lenses FIG. 1 SCHEMATIC OF THE PRINCIPLE OF OPTICAL COMPENSATION i a — film; h — spindle; c — tilting mirror ; d — spindle ; e — fixed mirror; f — screen; 1, 2, 3 — positions of picture ; b — diaphragm ; 1', 2', 3' — positions of tilting mirrors CONTINUOUS PROJECTION BY OPTICAL COMPENSATION First publication anywhere of data (direct from Germany), relative to the new Mechau sound-film continuous projector H. A. Robiczek Copyright, 1932, by James J. Finn Publishing Corp. Reproduction in whole or in part without permission forbidden. IN order to present a moving picture it is known to be necessary to produce a stationary object before the eye in a rapid succession of pictures, each of which presents a timely and spatially different position, although the interruptions may not become too large. Processes of movement of everyday life, taking a minute have to be retained in about 1,000 film pictures, if jerky movements are to be avoided in the reproduction. According to the principle of jerk (intermittent), conveyance of the film which, together with the Maltese cross and the shutter, have experienced general technical realization, the succeeding film pictures are presented to the eye in a really stationary position. The change from one picture to another, i.e., the film conveyance, is kept completely invisible to the eye, because of the shutter. Through the protrusion of the shutter, intervals of darkness originate between the individual pictures, causing an uninterrupted change from light to dark. This continual change affects the ocular nerves and, through these, the brain and head nerves of delicate persons to a high degree. The personal discomfort to which such spectators are subject often is reflected in subsequent derogatory statements relative to the motion picture in dustry. In addition, film and mechanism, during jerky transport, are subject to particularly heavy wear, and films already showing perforation defects are not conveyed properly by the switch gear, thus not permitting maximum efficiency of presentation. The Mechau Development For these reasons, it has been the aim of expert workers since the introduction of motion pictures to replace the jerky film conveyance with a device for optical compensation of the film movement. All makers of motion picture projectors have tried their hand at solving this problem; hundreds of patents of the most varied description relating to this phase of the art have been filed, at enormous cost; but the actual solution was only recently achieved by E. Mechau, in cooperation with the Leitz Works, Wetzler, Germany. With an apparatus with optical compensation of film conveyance, the individual pictures are no longer projected during the stationary position of the film, but during uninterrupted film conveyance. A part or entire revelation of this continuous film conveyance through a shutter, such as in Maltese cross projectors, would thus be superfluous. On the other hand, an optical device to project still reproductions from the continually [14] moving film tape on to the screen becomes necessary. Great difficulties were encountered in endeavoring to make the film movement invisible on the screen through an optical device including movable lenses, prisms and mirrors, and to move the projection of one film picture into that of the next one without pauses of obscurity. The idea of the optical compensation device of this machine is as follows: Projection Process If a film picture is situated at 1 (Fig. 1), and the mirror c is in position 1', reproduction on the screen is caused at /. If now the film picture moves downward into position 2, a corresponding transfer of the reproduction on the screen is caused, if mirror c remains in position 1' during the movement. If, though, it is simultaneously brought into position 2', the reproduction remains at /, and its movement on the screen is optically compensated for. The same condition prevails if film picture and mirror arrive in position 3 and 3', respectively, at the same time. In the same instant the following film picture appears at 1, its movement also having to be compensated for. For this purpose the mirror c also describes a revolving movement around its spindle h