International projectionist (Jan 1963-June 1965)

New Screen Design Developments Allow Brighter, Cleaner Projection Motion picture screens are better tiuia\ than e\er before in the history of the theatre. Not onI\ has the reHecting surface been made brighter but with an increase in gain it has been possible to greatl) improve side viewing conditions. Pearlescent pigments are responsible for increased efficiency. These pigments have been a\ailable in artificial form for main. many \ears and now there is available to manufacturers a natural pearl essence of unusual]] high purity. The lustre of this natural pearl surface not only increases initial brightness gained but the optical performance at wide viewing angles is of a high standard. The unique orientation of the pigments in the plastic mix ac( omits for this. Also available on the market today is a surface that has anti-static qualities and which is claimed to repel the attraction of dust. The industry has recognized the dust problem for a long time. Even with the protection of a screen curtain, the picture image is nevertheless exposed all during operating hours to a large volume of air in motion. Dust-laden atmosphere accounts for an a\erage light loss of 10 to 15 percent each year. This, together with normal oxidation, accounts fur regular deterioration of the reflecting surface. Now. for the first time, the dust problem can be materially reduced and the efficiency of the reflecting surface maintained for a longer time. Screen Brighreners Projectionists everywhere have read with great interest the report of the Motion Picture Research Council on the problems of screen brightness in outdoor theatres. The fact that their investigation showed some 57' . of all drive-in theatres surveyed had center screen brightness levels under three foot lamberts comes as no surprise. Indoor standards are 9 to 14 foot lamberts of reflected light, leaving most drive-in screens far short of what is considered a satisfactory level. There are. however, one or two compensating factors which must be taken into consideration. Firstlv. visual acuity, which in simple terms is the ability of the human eye to perceive detail, increases as the size of the picture image increases. Therefore, the very large size of modern drive-ins is in itself a great help to the eye even though light is lacking. W hat is known as a satisfactory picture is the result — satisfactory in the sense that the public accepts the presentation without complaint. This should not deter any one from tr\ ing to improve a situation that definitely needs improvement. Secondly, the usual combination of arc light and a reflecting surface that creates light that is predominantly in the yellow-while part of the spectrum enables the human eye to respond well. Hard) and Perrin in their " Principles of Optics" show that the response curve of the eye is greatest <n that portion of the spectrum between green and yellow. This means that the threshold of \ ision is greater in this area than it is say, for blue or red. It should be clear at this point that a properl) designed reflecting surface i> <>l tin greatest importance. Fortunately, a pure while surface is perfect although it brightness gain leaves a lot to he desired. However, combining available reflecting surface with modern light sources permits the average drive-in in gel li\. This is real!) not enough. Effort is constantly being expended by man) in the industry to improve the situation. So far. reflecting surfaces of higher gain have made some progress but the problem requires a substantial expenditure of monev . New surfaces have been plannd but man) cannot lick the problem of weathering, normal expansion and contraction and screen surfacings that are not uniformly applied and in perfect alignment, panel to panel, from side to side and from top to bottom. Applying higher gain panels on top of existing surfaces will, in most cases, make the new panels appear like a mosaic, simply because they cannot be perfectly aligned. The most commonly used surface application is still white projection paint because of its comparative ease BRIGHTER LIGHT LONGER BURNING SHARPER PICTURE Free Test Samples IH¥*WV TT?r>'iTim of application and its reasonable cost. It can also be removed without too much difficulty when complete retreatment is necessary. Until something practical comes along the drivein exhibitor should look to the following: An adequate light source. An efficient optical system. Proper selection of apeiture size. A clean and well maintained screen surface. Equipment to do a good job is readily available and supply dealers are prepared to improve conditions with the exhibitors desire to do so. iP America's headquarters lor all theatre equipment supplies National THEATRE SUPPLY COMPANY MODERNIZE POWER UNITS No burned contacts, cooler operation, smoother current with BE silicon rectifiers. A model to replace any bulb type. One year guarantee BROWN ELECTRONICS 1717 South St., ALLENTOWN, PA. awaute^^(^and(M^ CARBONS INC., BOONTON, N. J. 1* if ■*■*■* ****ii r • t*i* * ■ STEADIER LIGHT LESS ATTENTION PERFECT COLOR BALANCE Free Carbon Chart International Projectionist August, 1963 17