Image characteristics of 35mm still camera lenses have been measured at the Laboratory of Modern Photography Magazine for more than fifteen years. In an attempt to speed up measurements and quantitative evaluations, a single image frequency was selected for those measurements on a photoelectric contrast-transfer optical bench. Comparisons were made of MTF curves obtained for a group of lenses, and comparisons were also made of subjectively judged photographic color transparencies and enlarged prints of black-and-white negatives taken with these lenses. When the MTFs and the relative rankings were correlated, it was found that an image frequency of 30 lines (or cycles) per millimeter yields good comparative judgements and good discrimination among the lenses tested. Similar correlations were tried for MTF values at 15 and 45 lines per mm. It was observed that better correlation is obtained when picture rankings and measured contrast at 30 lines per mm are used. When combined with resolving power obtained from measurements of fine-grained black-and-white negative film, a consistent and repeatable relative evaluation is achieved.
"Single Image Frequency Measurements Of Camera Lenses", Proc. SPIE 0237, 1980 International Lens Design Conference, (16 September 1980); doi: 10.1117/12.959122; https://doi.org/10.1117/12.959122