Zero-Shift Test for Determining Optimum Density in Variable-Width Sound Recording

In variable-width sound recording, the fidelity of the recorded wave form depends in part upon the sensitometric conditions to which the photosensitive materials are subjected. The well-known cross-modulation test is available for determining the optimum sensitometric conditions which result in minimum distortion. — Another method of determining the optimum density under any given processing conditions, the zero-shift test, has been used for several years in the Kodak Research Laboratories. In this test, the average transmission of a high-frequency sine-wave track is compared with that of an unmodulated, unbiased track at the same image density, by means of a simple physical densitometer. At optimum density, where photographic distortion is minimum, these two transmissions are equal. Measurements at a single image density show directly whether that density lies above, below, or at the optimum. Optimum density thus determined is in good agreement with that found by the cross-modulation test. The equipment required is simple and only a small amount of film is needed. The zero-shift test is recommended for use in cases where the more extensive cross-modulation test is not believed to be justified.

Print ISSN

0097-5834

Published

1949-05

Content type

Original Research

DOI

10.5594/J12488