A study was undertaken to gain information concerning the mechanism by which a high contrast emulsion is developed to a significantly increased exposure latitude, without loss of toe speed. Developer properties were altered through variations in pH, bromide ion concentration, developing agent concentration, and the Phenidone */hydroquinone ratio. The results indicate that the bromide ion concentration is the predominant factor reducing both the exposure latitude and the toe speed. The experimental evidence suggests that the bromide reduces the rate of development throughout the exposure range. The other facts investigated produced primarily changes in development rate without affecting the latitude at a given contrast, until the rate and exposure are sufficient so that exhaustion of available silver occurs. The ability to increase the useful exposure scale without loss of toe speed depends upon maintaining a relatively constant rate of development over the desired exposure range, and having no soluble bromide present. *Ilford trademark.
Library of Congress Subject Headings
Photography--Developing and developers
Department, Program, or Center
School of Photographic Arts and Sciences (CIAS)
Egnoto, Susan A., "Investigation into the mechanism of development to increase exposure latitude without loss of threshold speed" (1981). Thesis. Rochester Institute of Technology. Accessed from
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