Adjacency effects, compensation effects, and related

[alanrockwood]

In my efforts to better understand the chemistry and physics of film development and image formation I think I have gleaned several concepts related to adjacency effects, compensation, and related effects.

It seems that some of the relevant concepts are localized developer depletion, localized pH changes during development, localized bromide concentration (the bromide being formed by during development), diffusion effects, both within the emulsion (horizontal and vertical) and in the boundary layer of the liquid in contact with the film during development, and the properties of the oxidized developer (e.g. is the oxidized product also a developing agent). Am I missing any important effects?

Of course, how these things interact will say a lot about the image, such as accutance and whether the characteristic curve is upswept or sigmoidal. Putting the concepts together to predict these properties could be a challenge.

 

[Neil Grant]

Highly diluted developer and minimal agitation. High localised object contrast, low flare camera lens. Not sure that oxidised developers are still capable of development. In chromgenic processes however, the oxidised developer can react with a 'coupler' molecule to form a dye - but this isn't development in the sense of AgX reduction. Your mystery deepens!

 

[Alan Johnson]

Acutance dyes in the film:
https://www.photrio.com/forum/threads/acutance-films.17461/
Iodide in the film:
https://www.photrio.com/forum/threads/the-placement-of-iodide-in-emulsions.147134/