Motion Picture Herald (1954)

‘ROBIN-ARC’ 3-Phase Selenium RECTIFIER Engineered fax WIDE SCREEN PROJECTION SYSTEMS Lamp Requirements for Wide-Screen Installations Presenting a study of light needs of wide-screen projection according to the system employed, and the size and type of screen, from a point of view somewhat different from that of similar data published in Better Theatres at various times during the past year or so. These calculations assume a specific variation of light transmission directly according to change in aperture area, An interesting addition is a "width ratio factor" for calculating further possible increase in picture size. A dependable, efficient, uniform D.C. power source. Engineered by pioneers in the motion picture field. Designed specifically for widescreen projection. Model K 150 100 Amps. Model K 100X40 60 & 100 Amps. Model K 100 135 Amp;. NEW “RO-RO” for single-phase current A newly patented attachment now permits satisfactory operation of 3-phase rectifiers off single-phase lines. Send for details. ROBIN-ESCO Super-Power MOTOR GENERATORS A quality product built especially for wide screen service and is available in 60 volts — 145 amperes, 80 volts — 135 amperes. These units may be operated on a continuous basis at these ratings. Write, wire or phone for details Sold through independent supply dealers OFQ J. E. ROBIN, INC. Motion Picture Equipment Specialists 267 Rhode Island Avenue EAST ORANGE, N. J. Manufacturers of RECTIFIERS • MOTOR-GENERATORS SCREENS • PROJECTION LENSES By ARTHUR J. HATCH Vice-president in Charge of Engineering, Strong Electric Corporation, Toledo THAT WIDE-SCREEN is here to stay is confirmed by the policies and commitments of major film producers. Many of the future pictures will be released either in CinemaScope or VistaVision processes. With a blessing on these two systems given by most, if not all, of the film producers, the exhibitor can proceed to equip his theatre with the reasonable assurance that the equipment he purchases will be suitable for the projection of whatever wide-screen system may eventually prevail. Those theatres that have already equipped for CinemaScope have learned whether or not they have ample screen illumination on the basis of their screen size. Theatres that have not as yet installed a large screen, and may or may not have suitable projection lamps, can approach the problems of solving their light requirements from two angles — First, that of determining how much light they will need to project a picture of the size which they intend to install ; or — Second, determining how large a picture they can present with their present projection arc lamps. With any wide-screen system of projection, having vastly increased screen area, there is a general requirement for more screen illumination than has been necessary heretofore. As the matter of film apertures and aspect ratios has been pretty well established for these systems, it is possible to present a few facts and comparisons from which conclusions can be drawn that will obviate a period of expensive experimentation. It is generally recognized that the maximum amount of light that can be put through present projection systems, using present designs of powerful arc lamps and optical systems, depends principally upon one factor: area of aperture. For instance, using the most powerful lamps, it is usually possible to put about 6500 lumens through a 16mm aperture. Using the same lamp it is possible to project approximately 23,500 lumens through a 35mm aperture, which has about four times the area of the 16mm aperture. Since the amount of light which is available to the screen depends primarily upon the area of the picture aperture, to compare the requirements of the various projection systems it becomes necessary to examine them on an aperture area basis. Most of the wide screen systems proposed use either an anamorphic type lens to expand the size of the picture, or use a cutdown aperature to accomplish the extended picture ratio. For instance, the non-anamorphic VistaVision system makes use of an aperture which is .825-inch wide (the same as the standard motion picture aperture which has been in use since the advent of sound) by .446-inch in height. These dimensions give an aspect ratio of 1.85-to-l to the picture when projected with a non-anamorphic lens. This aperture has an area of ,368-sq. in. The system whereby VistaVision employs anamorphic prints uses the present standard aperture .825 x .600-inch, and obtains the wide screen effect with an anamorphic lens that has a magnification [expansion] of 1^2-to-l. As the ratio of the standard aperture is 1.33-to-l and is anamorphized at a lT>-to-l expansion ratio, the projected picture has an aspect ratio of 2-to-l. This standard aperture has an opening area of .495-sq. in. The CinemaScope projection system makes use of a still larger aperture, one Arthur J. Hatch 34 MOTION PICTURE HERALD, OCTOBER 2, 1954