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252 PROGRESS COMMITTEE WORK [J. s. M. P. E.
tionary with the shutter open, or with the shutter running and with no film?
MR. WOLF: We have data under all conditions. In preparing the tests we made measurements both with the shutter standing still and with it in operation. We made the measurements, also, of auditorium illumination and other quantities. The screen reflection factor was eighty per cent, and the size of screen was nine by twelve. The auditorium illumination varied from 0.2 to 0.5 foot candle. The amperage of the high intensity arc varied from 7 to 4.2; of the lower intensity, from 7 to 4.7.
PRESIDENT CRABTREE: What were the limits of variation due to screen size? Do you recall, Mr. Farnham?
MR. FARNHAM: The smallest screen used was approximately four feet and the largest twenty-two feet, a linear ratio of one to five and one-half. However, the ratio of brightnesses was more nearly two or three to one, the smaller picture requiring the higher intensity, but it was by no means an inverse ratio.
PRESIDENT CRABTREE: Suppose a value of seven were required for a twentyfoot screen, what would be the value for a four-foot screen? Would it be greater than thirteen?
MR. FARNHAM: As near as I can recall, the smaller picture would require two to three tunes the intensity ratio.
PRESIDENT CRABTREE: Is the Committee considering the effect of screen size?
MR. WOLF: Yes, it is; but sufficient time was not available.
PRESIDENT CRABTREE: If any of you are in New York I would recommend that you visit one of the Trans Lux theaters where pictures are projected from the rear of the screen. The most amazing thing is that the brightness level in the theater is as high as it is in this room, and yet the picture is adequately bright.
MR. GAGE: With a small screen close by or a large screen far off, both subtending the same angle to the eye, and with the same foot candles of illumination would not this give equally desirable results on both screens? If so, it is necessary to relate the distance of the observer to the screen size rather than simply say that a twenty-foot screen requires so many foot candles, and a thirty-foot screen so many foot candles, etc.
PRESIDENT CRABTREE : That would depend on the opacity of the atmosphere.
MR. WOLF: We did find a difference in the reactions of viewers as they moved away from the screen. But the brightness is the same whatever the distance may be.
PRESIDENT CRABTREE : Not if there is absorption, and the air is full of smoke.
MR. WOLF: That effect is not appreciable.
PRESIDENT CRABTREE : I urge the Committee to push forward the experiments as rapidly as possible, because I am anxious that our Society should be the first to propose a definite standard of screen brightness with the necessary qualifications due to the various factors involved.
ORGANIZATION OF PROGRESS COMMITTEE WORK
For three years the past-chairman of the Committee has assisted in the preparation of the semi-annual report, and it has occurred to him that a re'sume' of the program of organization may be of some value