The Technical Basis of Photographic Speed Determination, or What is a Normal Exposure?
This tutorial paper examines and explains the methods used to relate to sensitometry the exposure needed to achieve a particular level of picture quality, to arrive at general predictors of correct exposure. Several standard methods of specifying film speeds are discussed in this context. Some specific experimental data are introduced to explain the influence of image structure on speed determination of black-and-white and color films. The sensitometry of “pushed processing” is examined, to explain the exposure levels achieved. The use of films at exposure indices much higher than those derived from speed standards is also discussed. The treatment is intended to be general enough to apply to still and motion-picture photography using both reversal and negative-positive materials.
- Print ISSN
- 0036-1682
- Published
- 1979-08
- Content type
- Original Research
- DOI
- 10.5594/J13181