New Criteria for Contact Printing in Aerial Photography*

Abstract

Print value in aerial photography carried out to meet technical requirements is determined almost entirely by the amount of recoverable information. This can be evaluated by measuring the photographic resolving power. The work reported here applies resolving power methods to the selection and exposure of contact photographic papers for aerial photography. Negatives on Aero Super-XX and Aero Panatomic-X have been used for the investigation. Most of the work was done with a chloride emulsion but some experiments with a bromide emulsion led to similar conclusions.It was found that with Aero Super-XX the most generally useful single print is made on a low contrast grade of paper, except for restricted brightness ranges of low contrasts. With Aero Panatomic-X, a single high contrast grade should be used. The higher resolution of the finer grained film is partially lost in the printing.Glossy paper preserves most of the available information on the film. It is adequate, but much inferior to transparencies. Other paper surfaces lead to more or less serious losses.Effects of inaccurate paper exposure are shown for different contrast grades. Exposure tolerance and resolving power over the useful range of the film indicate the lower contrast grades to be the most useful for the great majority of air negatives on Aero Super-XX.Great overexposure but only slight underexposure of film may be compensated for in printing. Maximum and minimum usable paper densities are given.