Especially for newcomers I consider a reversed tonality better to understand, open gate depicted as max. transmission, thus max . brightness.
Nice topic for discussion!
Did you note the pH of the first developer which gave you a small amount of fog?
Did you check to see if you lost speed with the lower pH?
If you scan an open frame, density should be very close to 0.00, not some number > 3 .... also frames with some b+f should have higher densities, not lower ones.
I fail to see the relevance. You have demonstrated 'fog' but did NOT demonstrate FOG IN RELATION TO THE IMAGE. Thus, there is no real comparison here. If a higher pH does deliver excess fog (common sense says that it does because you ARE developing 'more'), what about the general contrast of the image?
In other words, whether one develops film for a much longer time in a low pH developer, or whether one develops film for a much shorter time in a high pH developer, one could very well end up with identical gamma (contrast index) with fog levels being, also, identical. I fail to see what has been proven. Maybe someone can enlighten me.
Bottom line: I have found that pH does NOT affect fog levels when the contrast level of the IMAGE must remain the same. Fog restrainers DO, like benzotriazole, especially in conjunction with excess hydroquinone (because the HQ forces more contrast out of the film and this excess contrast acts, in a relative sense, to reduce threshold density).. - David Lyga
OK, I am with you, Adrian, it is just that the more you develop the more the fog is there. The fog would be just as great if you had a low pH and developed to the same gamma. - David Lyga
With the right developer formulations you can get both high contrast and low fog (think D-82), and low contrast with high fog (think POTA). Yes, most developers build up fog as they increase contrast, but the ratio contrast/fog is not constant.OK, I am with you, Adrian, it is just that the more you develop the more the fog is there. The fog would be just as great if you had a low pH and developed to the same gamma.
David, you’re knowledgeable about developing old film with old exposures aren’t you? I know Adrian’s next steps are to check ‘gamma’ (and speed), which simply dropping pH might impact, but I expect there is a formula that restrains fog while still developing a usable image.
There are good formulas for that aren’t there? I assume they would have lower pH than usual, but I don’t know ‘chemistry’ - I am a cookbook type person.
Yes, a 'fog formula' would have to encompass both benzotriazole and extra hydroquinone. The BZ restricts threshold density while the HQ emphasizes tonal distance between the threshold and highlights. - David LygaDavid, you’re knowledgeable about developing old film with old exposures aren’t you? I know Adrian’s next steps are to check ‘gamma’ (and speed), which simply dropping pH might impact, but I expect there is a formula that restrains fog while still developing a usable image.
There are good formulas for that aren’t there? I assume they would have lower pH than usual, but I don’t know ‘chemistry’ - I am a cookbook type person.
Yes, a 'fog formula' would have to encompass both benzotriazole and extra hydroquinone. The BZ restricts threshold density while the HQ emphasizes tonal distance between the threshold and highlights. - David Lyga
That table salt does not only contain iodide as restrainer, but mostly chloride, which in larger amounts acts as silver solvent, c.f. Microdol and Microdol-X. I would suggest that this is where the fain grain effect comes from.
David, you’re knowledgeable about developing old film with old exposures aren’t you? I know Adrian’s next steps are to check ‘gamma’ (and speed), which simply dropping pH might impact, but I expect there is a formula that restrains fog while still developing a usable image.
There are good formulas for that aren’t there? I assume they would have lower pH than usual, but I don’t know ‘chemistry’ - I am a cookbook type person.
Adrian, I am confused by densities near 1 and 0.5, have you also not subtracted the open gate reading?
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