Society of Motion Picture Engineers : incorporation and by-laws (1927)

Polygonal Floodlight Mirror — Benford and Palmer 115 beam from all twenty-five sections has twenty-five individual beams with over one hundred scallops and the multiple form of the beam is visible only around the extreme edges and not at all in the center. This 25 section mirror gives 25 indi^ddual beams from the 25 images that are back of the mirrors, and an opaque object in the beam therefore casts 25 shadows. This feature has been given some study Fig. 5 — A study of the shadows formed by a polygonal mirror. There is a separate shadow for each section of the polygon, 16 in tliis particular case. because it was once thought that this compound shadow might be objectionable. It has since been found that in studio practice this form of shadow is to be preferred to the sharp and clear shadow from a parabolic mirror. There may, of course, be exceptional cases where the sharp shadows are to be preferred, and therefore data on the subject is of importance. In taking the shadow photograph of Fig. 5 the five subjects were arranged as follows. The man on the left was 5 feet from the white screen. The others were spaced back at 5 foot intervals so that the man on the right was 25 feet from the screen. The floodlight itself was 60 feet away on a line normal to the center. The progressive separation of individual shadows produces a peculiar type of com