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Exposure Meter for High-Speed Photography
BY E. T. HIGGONS
WESTON ELECTRICAL INSTRUMENT CORPORATION, NEWARK, NEW JERSEY
Summary — This paper reviews the problems involved in the process of evaluating high-intensity illumination levels and the establishment of proper exposure criteria for high-speed motion picture cameras. The problems involved in the design of a suitable light-measuring instrument are discussed, concluding with a detailed description of a light meter which has recently been developed specifically for the purpose of determining proper camera settings for high-speed motion picture studies under any lighting conditions from normal daylight to illumination values as high as 300,000 foot-candles.
EXPOSURE VALUES in standard photography are at present determined by one of the following three methods :
1. By the individual's personal experience with his own particular photographic equipment operating under light conditions familiar to him.
2. Through reference to exposure calculator charts commonly furnished by the film manufacturers, the use of which are dependent entirely upon the user's ability to classify typical lighting conditions.
3. Through the use of photoelectric or extinctiontype exposure meter.
All three of these methods involve either consciously or subconsciously the determination or evaluation of the scene brightness or illumination and a correct interpretation of its effectiveness in respect to the camera and the film.
When high-speed motion picture studies are to be made with normal daylight illumination, a standard photographic exposure meter may be readily adapted to the problem of establishing exposure criteria. Unfortunately, many high-speed studies cannot be made with sunlight illumination. In addition, it is sometimes very desirable to shoot at frame speeds far in excess of those possible with available sunlight. Therefore, it becomes necessary for most work to resort to
* Presented April 6, 1949, at the SMPE Convention in New York.
NOVEMBER, 1949 JOURNAL OF THE SMPE VOLUME 53 545