British Kinematography (1950)

88 BRITISH KINEMATOGRAPHY Vol. 17, No. 3 instead of a constantly lit foreground and an intermittently lit background. The cameraman was thus assisted in securing perfect balance of lighting. 5. Automatic Water Sprinkler. This had been designed for the purpose of supplying a silent rain supply when production necessitated a direct recording, the normal supply being impracticable under such circumstances. The machine consisted of a rotating sprinkler which was filled from an external supply pipe. The machine was silent in operation because all air was ejected from the sprinkler. The intensity or size of the rain drops was governed by the size of the perforation in the sprinkler, floor coverage by the speed of the rotation of the sprinkler. REFERENCES 1. Brit. Kine., 16, No. 2, February, 1950, 4. Brit. Kine., 15, No. 3, September, 1949, P "' Noiseless Water Sprinkler. 38. 2. Brit. Kine., 17, No. 1, July, 1950, p. 5 3. To be described later in this Journal 75. 5. /. Soc. Mot. April, 1947, p. 353. DISCUSSION Pic. Eng., No. 4. Mr. R. H. Cricks : A fault often seen, even in features, is that of wheels standing still or turning backwards. If the flickertype view-finder were used on such scenes, the cameraman would be able to avoid such stroboscopic effects by adjusting the speed of the wheel. Mr. George : Yes, the cameraman would be able to see the effect and slow down or speed up the wheel. A Visitor : Is anything being done in the way of automatic focus ? Mr. George : Yes, we have used it on a model. We had a shot in " Uncle Silas " where we had a 27-ft. model with forced perspective, the focusing point being on a door. The camera had to track from one end to the other, holding the door in focus during a 27-ft. travel down to 9 ins. We used a Magslip generator and a slave motor. Unfortunately the movement of the lens is not linear, consequently it would mean a rather involved form of cam ; therefore the master generator was operated by hand. Mr. G. Hill : Automatic focus would be extremely useful even in normal fixed shots. It has been used for years on model and trick work, but unless you can get the artistes to hit the particular spot every time, it is difficult to operate. A Visitor : Why was the Selsyn put on the lens of the projector to line the picture up ? Why not on the projector itself ? Mr. Gow : The lens has been designed in such a way that it will cover the movement in three directions. Mr. Benson : Needing a fog machine on location where there was no power, we used a baby Calor. Mr. George : You can get almost the same effect with smoke powder, or with a special candle which I have recently obtained from Germany. Mr. W. S. Bland : With regard to the flicker shutter, I wondered whether you could get over the difficulty by having a different shutter for lining up, with the flicker blade on it arranged to pass the same amount of light. The cameraman would not then be conscious of the flicker in his background. Mr. George : The projector shutter usually has a similar opening to the camera shutter. With the ordinary projector you could afford to do that, because the pulldown period is less than 90°. Mr. Bland : With regard to the thyratron-operated photo-floods for flicker effects, it would be simpler if you recorded the effect of the flicker from the original photo-cells upon magnetic tracks, and then had the pick-ups lined up so that the halfdozen bits of flicker were fed to the photofloods. You could have a loop of tape. Mr. George : We have invariably to put a practical fire in the set, and we use the actual flames. Mr. Bland : The trouble with the use of moving slides for background skies is that clouds moving across the sky never move in constant relation one to another. Mr. Gow : We have found that the use of two or three glasses moving against one another gives a very realistic effect. Mr. Benson : Have the authors found any way of strengthening soap bubbles ? Mr. Pearson : I shall be pleased to assist the speaker. I have had bubbles which travelled as much as 200 feet.