Jay Johnson


An intensity scale monochromatic sensitometer was constructed using a Bausch and Lomb single-pass diffraction-grating monochromator as the dispersing device. A ribbon-filament tungsten lamp was used to supply the radiant energy to the monochromator. The instrument was calibrated 2 radiometrically and was shown to have a maximum irradiance of 10 ergs/cm 2 2 at 425 nm, 43.7 ergs/cm at 550 nm and 26.1 ergs/cm at 700 nm. Exposure is accomplished by transporting the film and step tablet past a slit at a constant velocity. Several film velocities and slit widths are available to produce exposure times ranging from 0.003 to 2.0 seconds. Spectral sensitivity measurements were performed on KODAK Panatomic-X and KODAK High-Speed Infra Red materials. The results were compared to information supplied by the manufacturer. The differences between the Rochester Institute of Technology curves and the manufacturer's curves were within 6 percent. The uncertainty in sensitivity of the materials being tested was found to be dependent on the local slope of the H and D curve at the density value selected for the determination of sensitivity.

Library of Congress Subject Headings

Photographic sensitometry; Monochromator

Publication Date


Document Type


Department, Program, or Center

School of Photographic Arts and Sciences (CIAS)


Not listed


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