Journal of the Society of Motion Picture Engineers (1930-1949)

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410 J. A. DUBRAY (J. S. M. P. E. disagreeable and fatiguing. It is obvious that the greater the rapidity of alternation of the two complementary colors the less noticeable the flicker will be. In order to achieve greater projection speed the movement of the Morgana projector is so designed that each forward movement of two successive frames at the projector aperture is followed by a backward or reverse movement of one frame, so that each picture frame is projected three times instead of once. The rate of projection at the aperture is therefore 72 frames per second, although the linear motion of the film at the feed and take-up sprockets corre COLOR ALTERNATION TIME EXPOSURE FIG. 7. Chart showing the alternation of color filters and the triple projection of each film. spends to a running speed of only 24 picture frames per second (7.2 inches). Fig. 7 shows graphically the relation between film movement, time of exposure, and color. The letters R and B indicate the color of the projection filters, red and blue-green, and the arrows indicate the direction of the movement. The graph illustrates the alternation of the red and blue-green filters, and the triple projection of each frame. The intermittent movement of the Bell & Howell regular Filmo projector is so designed that for every frame "pulled down," the single-bladed shutter revolves three times. In the Morgana projector, motion is imparted to the film for every revolution of the shutter, the cycle of motion being as stated above, causing a movement of