Increased chemical adjacency effects in black and white photography can be obtained using certain Metol and Phenidone developers. Four different effects are described: 1) development inhibition by iodide ion 2) development inhibition by bromide ion 3) exhaustion of Metol 4) development inhibition by oxidized Phenidone Edge effects produced by Metol exhaustion and by Phenidone development are enhanced by moderate increases in pH. They are reduced by: the addition of hydroquinone, high levels of sodium sulfite, and high fog levels. Developers designed to increase adjacency effects also increase granularity. The trade-off betv/een acutance and granularity is approximately linear for the film-developer combinations studied, with the exception of a Phenidone only developer, which resulted in excessive granularity. With low-speed films like KODAK Panatomic-X, the sharpness increase observed in photographic prints may be beneficial in spite of increased graininess. However, with higher speed films such as KODAK Plus-X and KODAK Tri-X, the increased grain overwhelms the gain in sharpness, making the trade-off unfavorable.
Library of Congress Subject Headings
Photography--Developing and developers; Photographic chemicals
Imaging Science (MS)
Zengerle, Paul L., "The Effect of Developer Composition on Adjacency Effects in Black and White Photography: Metol vsl Phenidone" (1983). Thesis. Rochester Institute of Technology. Accessed from
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