[QUOTE=Kirk Keyes;853451]Pat - I'm pleased you've taken to the world of pdfs so quickly, but I think you might find you can post photos as jpgs that look better than photos as pdfs.
Here are .jpg files, overall and detail. These are from direct scans of the negative. I think you are right. Even at much reduced file size they look better.
I think that looks better - no artifacts from the pdf. You posted a photo in the Part I that the pdf had mangled so much it looked like it had been transmitted via a 1950s facsimile machine!
The rate of aerobic oxidation of ascorbic acid has maxima at pH 5 and 11.5 (google ascorbic acid oxidation pH lester packer).
If that is true the ascorbate version at pH 14 will probably not be as resistant to oxidation as Rodinal.
However it may show considerable increase in film speed.
Is there a formula to test yet?
I am a coffee addict...
Originally Posted by Ian Grant
Maybe you could also think about a Rodinal-like Caffeinol+C potage... :D
That would also answer my eternal nagging that a standardized, reliable no-surprise Caffeinol would be the next great thing.
Here is my dream:
A developer based on caffeic acid and/or vitamin C. It should be highly concentrated, and of course it should last forever and make full film speed or even pushing possible. We need two versions:
- High acutance, lots of grain, like Rodinal
- High acutance, no grain, like Perceptol :D
That will not be too difficult, right?
Sorry to butt in but I've never used Perceptol and am interested in its "high actance / fine grain" properties. I million years ago when I was processing my own film I used Rodinal and LOVED the acutance but had to put up with the grain.
Does Perceptol possess as much acutance as Rodinal?
Is the grain truly that much finer than Rodinal?
Only at 1+2 or 1+3
I can't comment on the grain, except yes it's fine with Perceptol, but I always got fine grain with Rodinal too using APX1oo, APX25 and Tmax 100.
[---- "Try Zero-Grane 999. Non-poisonous. Enlargement to 999 diameters, miraculously discovered by George Gizzlewski after 84 years of painstaking research. If it won't develop your negative, take two teaspoonsful after each meal. It puts spring in your step and a light in your eye. $10 per 2 oz. bottle sufficient for 89 rolls of film."[/I]
Edmund Lowe, 1939
Made my morning. Lowe had a sense of humor. I must needs now chuckle each time I use some FG-7.
Perceptol has a LOT less grain than Rodinal. Well, so do XTol and all other developers. If you want grain try APX 400 in Rodinal and push it to 1600.
Originally Posted by Mike1234
Ilford Perceptol alias Kodak Microdol-X is not too bad in terms of acutance, and it becomes pretty good at 1+3. But with most films you lose some speed. And of course it is not as comfortable to use as Rodinal and does not last for centuries.
I wasn't thinking of such a high pH. I want to stay below the point where ascorbates alone are active. Ascorbate will still serve to regenerate oxidized Metol at pH = 8.7, at which pH it produces results like those of sulfite. This is the reason it works in place of sulfite in the Pyrocat developers that are dissolved in glycol. Its function there is to allow Phenidone or p-aminophenol or Metol to interact synergistically with the catechol when water is added to the glycol stock as sulfite does in the water stock.
Originally Posted by Alan Johnson
We think of Metol-hydroquinone as a superadditive pair, but the superadditivity does not work without sulfite or ascorbate.
The developing agent in Rodinal is potassium aminophenolate with sulfite preservative. It is more an analog of D-23 than anything else, if you choose to look at it that way. If we could buy (maybe we can) potassium p-aminophenolate, we could probably get the same result as Rodinal by putting it in a solution with sulfite, and not worry about how the phenolate was manufactured. Now substitute potassium ascorbate for the sulfite and see what happens.
That's just it though. I want the best of both worlds... extremely high acutance and fine grain. By far, I care most about acutance and would never give that up for fine grain. I'll just shoot the biggest film I can carry the equipment for.
Originally Posted by cmo
If there is a very high actance developer (at least as good as Rodinal) but with finer grain then I would certainly give it a try.