A Comparison of Multiple-Exposure Methods of Sensitizing Photographic Emulsions for Short Duration Exposures

Abstract

Multiple-exposure methods of sensitizing photographic emulsions for recording light flashes of less than 10^-4 seconds duration were compared. Hypersensitization could not be used because of the graininess produced. Maximum emulsion sensitivity for the photography of large objects was obtained by using a combination of high intensity pre-exposure (of less than 10^-4 seconds duration), and subsequent post-exposure with very low intensity light. A 3.4-fold increase in sensitivity was obtained. Both high intensity pre-exposure, and low intensity post-exposure were more effective than pre-fogging. For the photography of very fine objects the total developed density and the graininess must be kept to a minimum. It appears that high intensity pre-exposure and low intensity post-exposure will give optimum results when the sensitizing exposures produce density changes of approximately 0.03 and 0.10, respectively.