A simple optical technique for placing a record of the camera aperture and focus conditions on each photograph is described. A lens system is installed in a NASA/Hasselblad lunar surface camera so that a small image of the camera iris is formed in the corner of the photographic image field. The camera aperture and focus settings that were used in the taking of the photograph are determined from measurements of -the width and position of the data image. A Fortran IV computer program which uses the system calibration data and iterative techniques to determine the settings from the image measurements is used and described. The relatively simple system employed in this investigation was able to resolve camera aperture settings of half- stop increments in the range of f/56 to f/16. In addition to detecting the three calibrated focus settings of 5, 15, and 70 feet, the focus values of 3, 3.5 k, and 8 feet also could be distinguished. Since the camera iris opening is imaged, a measure of the inherent iris variability is obtained during normal system calibration.

Library of Congress Subject Headings

Photographic optics; Photographic lenses

Publication Date


Document Type


Department, Program, or Center

School of Photographic Arts and Sciences (CIAS)


Carson, John


Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works. Physical copy available through RIT's The Wallace Library at: TR220.T46


RIT – Main Campus