Reciprocity testing of Kodak film type SO-289 multispectral infrared aerial film

Kodak multispectral infrared aerial film type SO-289 was tested for reciprocity characteristics because of the variance between the I-B sensitometer exposure times (8 seconds and 4 seconds) and the camera exposure time (1/500 second) used on the ASTP stratospheric aerosol measurement project. Test exposures were made on the flight emulsion using a Mead star system sensitometer, the films were processed to ASTP control standards, and the resulting densities read and reciprocity data calculated. It was found that less exposure was required to produce a typical density (1.3) at 1/500 second exposure time than at an 8 second exposure time. This exposure factor was 2.8.