Motion Picture News (Nov-Dec 1923)

2604 Motion Picture News REFLECTION FROM METALLIC SCREEN 175 — Distribution of reflected light from metallic screen Fig. 172 — Typical wide motion picture house requiring a diffusing screen preciably cut down the efficiency of the screen, especially with the Mazda projection lamp. Moreover, the softer quality of the light from the Mazda lamp when not modified by a blue screen, is considered preferable. Selection of Screen: The diffusing or flat white screen is superior to the metallic or beaded one for certain types of theatres only. The diffusing screen is essential in an auditorium which is wide in proportion to its length. In this case the picture must be viewed at a considerable angle from the center and it is necessary for good results that the screen appear equally bright when viewed from any position. An example of such a condition will be seen in Figure 172. The metallic or the beaded screen is very desirable for a long and narrow house. The brightness of the screen, as viewed from directly in front or almost so, is much greater than in the case of the diffusing screen. The objection that brightness is very low when the picture is viewed at a considerable side angle naturally does not apply in this case. Such a situation is illustrated in Figure 173. One striking manner in which the light from the beaded screen differs from that of the metallic screen is shown in Figures 174 and 175. When the projected light strikes the metallic screen at an angle, the resultant light is reflected somewhat downwards. In the case of the beaded screen, however, the light is reflected to the maximum extent back along the piojeeted beam. Particularly in the case of a house having a high projection booth, care must be taken to see that a screen type and location are chosen which will produce satisfactory picture brightness for the entire theatre. Location of Screen When the diffusing screen is used it appears to be of the same brightness no matter how high it may be placed on the stage. With a metallic or beaded screen, it will be seen from Figures 174 and 175 that the location has some effect on the distribution of light, and should be taken into account when designing the theatre. Brushing Screens: All types of screens should be brushed carefully at least once a month. Use a clean soft counter brush and stroke the screen carefully, either straight across or up and down, brushing always in one direction only. Washing and Resurfacing Screens: Practically all flat white screens, even those which do not have a surfacing of paint, can be washed without injury. Clean with a soft brush, castile soap and water every two to six months. Flat white screens which have a painted surface can more satisfactorily be resurfaced than washed. Every two to six months give the screen one or two coats of a flat white. Water color paint is preferable to oil paint. Metallic screens will lose only a little in efficiency the first two or three cleanings, but repeated cleanings will reduce the efficiency more and more, hence do not use soap or wall cleaner on these screens more frequently than once in six months unless dirt conditions are unusually bad. Most manufacturers of metallic screens will resurface them at a reasonable charge. Washing Beaded Screens The best quality beaded screen can be washed without injury. Do this every two to REFLECTION FROM BEADED SCREEN 175 — Distribution of reflected light from beaded screen six months, depending on dirt conditions. Proceed as follows: 1st. — Construct a trough of wood or metal, which will rest along the bottom of screen, placed in position to catch the excess water. It is-well to make provision for draining this trough, preferably with a hose attached to it. 2nd. — Starting at the bottom and going from one side to the other, sprinkle the screen with cold water by the use of either a hose or sprinkling can, until screen is thoroughly wet. 3rd. — Using an ordinary scrubbing brush, castile soap, and cold or lukewarm water, start 200 10° 20* 30° 40" 50* ANGLE FROM NORMAL 60' Fig. 170 — Distribution of reflected light from three types of motion picture screens from the bottom, working from one side to the other and thoroughly scrub the entire surface. Use plenty of soap and water and do not be afraid to scrub the screen hard, as any reasonable scrubbing will not injure it. 4th. — Rinse the screen well, starting from the bottom and working from side to side, using either a hose or sprinkling can. Now, but not until now, the screen should be allowed to dry thoroughly. Always start at the bottom and work from left to right, right to left, etc., when wetting, scrubbing and rinsing, to obtain perfect results without showing streaks. General Care of Screen The useful life of the screen surface may be considerably increased by hanging a curtain directly in front of the screen, so arranged that it can be pulled to one side when pictures are being shown, but used as a covering at all other times. As a dust and dirt protection this is particularly good where screens are tilted instead of vertical as the former are more likely to collect a large amount of dirt. When no such curtain is used, it is a good plan to direct one or two electric fans to keep dust and dirt from settling on the screen during clearing of the audience. The useful life of the screen is so largely dependent upon local conditions, on the care taken and on the quality of the screen itself, that it is difficult to forecast. Screens usually last from one to five years. A life as short as {Continued on page 2610) Fig. 173 — Typical long and narrow motion picture house requiring a metallic or beaded screen