Quote Originally Posted by Photo Engineer View Post
So, lets just take the case of a film with very coarse grains but with very large edge effects. Is it very sharp or very grainy or is it to be described in another fashion? Each person here on APUG would probably evaluate the film in their own special brew and then "name" the film's features after what they find with their ever so precise (subjective or objective - which do you think is done more often?) tests.

PE
I guess that's the problem. Even in the thread Alan linked to, it's about 99% nonsense, especially once you get Rodinal and staining/tanning people involved. But I suppose I'm differentiating actual sharpness from characteristics that can enhance the impression of sharpness. Edge effects, for me, fall under the latter category. With a given resolution, acutance (excluding edge effects) has mostly to do with the film itself and exposure, so turbidity, emulsion layers and thickness, homogeneity, acutance dyes, anti-halation and other things. Then there is the exposure itself, which of course causes some degree of irradiation etc. depending on the film characteristics. These things determine the actual acutance. I don't think developers can do much with that. I think they mostly influence graininess (as evidenced in the Altman/Henn study), and to some/varying extent edge effects. And I also think when people see pronounced grain they see sharpness.

I also agree in the end generalizations are tricky. The Altman/Henn study and Henry's tests showed this. Who would ever expect stock D-25 to be sharp? Well it certainly seemed to do just that with Panatomic-X.

Another question (ultimately in relation to the sharpness/grain masking claims made by people formulating tanning/staining developers). I think I remember reading somewhere in Haist (can't seem to find it now though) about additives in colour emulsions to prevent dye spreading - in other words to keep the dye from forming too large a cloud around the silver. Am I dreaming that up or is it real?