International projectionist (Jan-Dec 1947)

VOLUME XXII MARCH 1947 NUMBER 3 Studio Super H. I. Carbon Arc Lamps By PETER MOLE Mole-Richardson Company, Hollywood "If it isn't on the film it will not show on the screen." The finest projection equipment and most expert craftsmanship "can't show what ain't." Means for satisfying the ever-increasing demand for more and better quality light on both sets and screens is cited in this article, written expressly for I. P. by Hollywood's foremost set lighting technician. //^PHAT outfit doesn't make pictures, I it makes silhouettes," a projectionist remarked when viewing a picture done in low key throughout. "And the producer of that stuff comes to the projection room during a preview and wants to know why I can't give him more light." The foregoing is not a condemnation of low-key photography where the cinematographer is after an effect and where he remembers that the picture on the screen is light. If there be nothing on the screen but silhouettes throughout the picture, he has produced off-key instead of low-key lighting. Fundamentally, the picture on the screen is the projection light source which is divided into light and shade by the selective absorptive properties of the motion picture film. Those selective absorption properties are density in blackand-white film, and density plus color in color film. The density and color on film is largely the result of the intensity and color of the lights used on the motion picture set. In following the advances in motion picture photography it is interesting to note that the trend is toward an embellished natural-appearing result rather than toward a synthetic lighting effect. Many cinematographers are creating "one-source" lighting effects which, as the term implies, give the effect on the screen as though all of the illumination were coming from one source such as the sun. Of course, many lights are actually used, but the main source must be sufficiently powerful so all shadows are cast in the one direction. This type of photography assures sufficient translucence in the highlight areas of the film so even when the "key" is very low there is enough light on the screen to hold the attention of the theatre patrons. The M-R Type 450 Lamp This trend created a demand for a studio set lighting unit with twice the light output of the Mole-Richardson type 170 lamp which operates at 150 amperes In order to meet this demand the M-R Type 450 lamp (Fig. 1) which has been dubbed "The Brute" by the studios themselves, was designed. Fortunately, this 100% increase in light output was obtained with only 50% increase in current. The Type 450 unit operates with a 16-mm X 22" super high-intensity positive carbon and a 17/32" X 9" cored Orotip negative carbon burning at 225 amperes and 75 arc volts; whereas the Type 170 lamp burns a 16-mm X 20" MP studio positive and a y2" X 8V2" MP studio negative carbon at 150 amperes and 67 arc volts. The newly designed Morinc condenser lens on the Type 450 lamp has a curved surface and is of 24" diameter which gives it a greater light pick-up angle than the 20" diameter flat surface condenser of the Type 170. The main advantage of the larger diameter curved surface condenser is that it provides for a greater arc-to-condenser distance at various beam divergencies, thereby minimizing the danger of condenser breakage from increased heat. The Type 450 lamp head is not just a modification of the Type 170. The 100% light increase and 50% current FIGURE 1. Mole-Richardson Type 450 lamp. INTERNATIONAL PROJECTIONIST • March 1947