Photographic Photometry Measurements - Associated with the Interpretation of Point Object Radiant Intensity

The extant problems of point source photographic photometry in relation to re-entry vehicle cinephotography lie in the areas of obtaining radiant intensity measurement accuracies better than 50%, and in analysis of large numbers of photographic images within a reasonable time span. This paper reviews these problems, demonstrates and assesses a technique to improve overall calibration accuracy, and presents quantitative data on point image microstructure, useful in predicting accurate values of film-scanner operational parameters. An experimental study is described in which cali-bration curves of point image area and diameter versus exposure were produced for four Kodak emulsion types. Parameter values were chosen to simulate those encountered on a typical re-entry photography mission. The capabilities and limitations of the isodensitracer as used in a calibration scheme are assessed.