Further Measurements of Illumination in Motion-Picture Projection

W. E. Story

The method previously described has been improved and applied to the measurement of the total illumination obtained on the screen with different source sizes and different condenser systems compared to the maximum obtainable with the given source brilliancy and given objective diameters. A comparison of the photoelectric measurements with the measurements obtained using an optical photometer for condensers of different absorption and sources of two slightly different brilliancies shows the ratio of the photoelectric cell readings to the photometer readings to be independent of color thru the range considered. Uniformity of screen, illumination is also taken up in a general way by the application of direct observation of the screen to the automatically drawn curves registering total illumination.

Print ISSN
Published
1920-05
Content type
Original Research
DOI
10.5594/J14219