Motion Picture News (Nov-Dec 1920)

3980 (Equipment Service) Motion Picture News MOTION PICTURE THEATRICAL STAGE ILLUMINATION SERVi CE world A specially designed auto truck complete with for locatio Designs Special Truck for Locations IN keeping with his policy of continually improving the Sun Light Arc and Sun Light Service, President Harmer has designed a portable lighting set to make possible the wider use of his high efficient arc in motion picture work. The new equipment, which consists of a complete power plant mounted on a S-ton White truck, together with the necessary arc equipments and cable, was assembled for one purpose — to make the lot of the director easier when his script called for location work far distant from any dependable source of power. This portable plant contains a generator driven from the motor of the truck and capable of delivering 450 amperes which is sufficient for three Sun Lights of 100,000 c. p. each. These three lamps may be burned indefinitely from this generator ar.d Sun Light Arcs is now available n work one generator but if necessary five arcs may be burned for a short time. No matter how far from the truck the scene is laid the director is enabled to keep in close touch with the operator by a telephone set. The Sun Light Arc has devised a rental system which will allow the use of the portable truck by any director in need of such a power plant. Experienced operators are sent out with each equipment which insures the best of results. This innovation on the part of President Harmer and his associates was carried out only after a year's study of the field. They now have the intimate knowledge of the requirements of the field that to enable them to design and assemble this new portable lighting set. The White Motor Truck Company who designed the truck for the special purpose have become interested in the motion picture industry and it is expected that these trucks will be found in many branches of the industry where transportation problems are to be solved. (Continued from page 3978 j aid in dealing with the topic : (1) The nature of the light sources; (2) The manner of their application; (3) The manner of installation of equipment. Under the first heading, consideration should be given to the color composition of the light, the degree of concentration of the light source itself, the nature and value of reflectors and auxiliary reflecting surfaces — and the nature and value of diffusing screens. 1. Color Composition of Licht The color sensitiveness of the photographic emulsion, of course, determines the usefulness of the spectrum range of the light source. The modern film used in the motion picture camera is sensitive over a considerable portion of the sun spectrum and consequently sunlight will record on the film more speedily and correctly than a light source in which one or more colors to which the emulsion is sensitive are absent or weak. Artificial light sources which do not cover the full sensitive range of the emulsion can not give maximum results, unless used in conjunction with other light sources which supply that deficiency. The mercury vapor lamp, though completely lacking in some colors, is nevertheless a valuable unit for this work, owing to its wonderful light diffusion and is very extensively used in conjunction with powerful arc lamps employing " white flame " carbons. There is a great deal of valuable information to be gathered on photographic color values, and it is to be hoped that the S. M. P. E. may lie favored at an early date with a paper on this topic by some of the many brilliant men of the Eastman laboratories. If a light source be considered as a point, the light would emanate therefrom equally in all directions, and the rays would all form diverging angles. Such a point of light would be the extreme concentrated light source. Consider now a plane surface, a square, for example, formed by minute light sources, whose collective intensity is equal to an assumed intensity of the aforementioned concentrated light source. (Continued on page 3986) WE ARE NOW LOCATED AT OUR NEW PREMISES 118 WEST 44th STREET HALF A BLOCK FROM BROADWAY IN MUCH MORE CONVENIENT AND COMMODIOUS QUARTERS (THIS NEW ESTABLISHMENT IS DEDICATED TO SERVE YOU FAITHFULLY AND WELL) THE MOTION PICTURE APPARATUS CO., Inc. We call your attention to our long experience and excellent facilities for serving you when it comes to doing your DEVELOPING and PRINTING. We are sure EVANS can please you better— much better in quality of work. Remember it costs you nothing to investigate. Why not do so now? EVANS FILM MFG. CO., 416-24 West 216th St., New York City Wadsworth1 3443-3444