What's your definition of compensation - true of otherwise?
Originally Posted by gainer
Also, your 2 ml line looks like it needs a bit more time. And have you tried 1 ml? And how is the mottling?
Back end foremost. No mottling that I can see in 10X enlargements of pictorial negatives. I would see it in these pictures if it were there. I shoot 36 exposures of the same scene, same exposure, camera on tripod. I develop a few frames at a time. All frames are identical. My previous tests with Rodinal and PMK as stand developers showed streaks from sprocket holes and uneven development from side to side. None of that here.
Originally Posted by Kirk Keyes
Haven't tried 1 ml/l. It takes almost that much to match the ascorbic acid mole for mole. I did try extending development to 60 minutes for the 2 ml/l mixture, and that is a little too much to match the others. I am about to do 50 munutes to see if I can hit the happy medium. Curve shapes for 40 and 60 minutes look to be about the same. By that I mean you could multiply one by a factor to get the other.
I'll be glad to snail mail you some prints and negatives if you will send me your address. My address is:
Patrick A. Gainer
2700 3rd Run Road
Glenville WV 26351
I consider compensation to be the increase in shadow contrast and decrease in highlight contrast that compensates for loss of film speed due to developing to lower than normal overall contrast. Not to the absurd length shown by the first H&D curves purported to be for Acutol, where the curve was actually concave downward starting at the speed point. I hope Crawley was not responsible for those exaggerations.
Kirk, meanwhile back at the farm, in looking over my charts it seems that the only real anomaly is stand development with 4 ml of TEA per liter. The shapes of the other curves are such that we might look at them, as you did the one, and say all they need to be the same is more or less time in the tank. I set out to find if there was a difference in curve shape that would favor more or less concentrated alkali. I have a feeling, an itch which I am about to scratch, that the 4 ml/l test needs to be redone. I think when I do it I will find that whatever difference ther may be between agitating and ruminating, it will not depend on pH or buffer capacity as long as development time is adjusted to get the same end points.
I held developing agent concentration constant. I probably should vary that and hold initial pH constant. I should also see if there really is a difference between agitating and ruminating.
I recalibrated my densitometer and found error, but it was a simple factor which had little effect on comparisons.
I got a little information on agitation vs rumination, whic is shown in the attachment. The same isoascorbate-amidol stock was used for both curves, with the difference in TEA content as noted. You may alo note that the 60 minute stand slope is lower than before. It is the same curve read again with the recalibrated densitometer.
The stand development made quite a difference. It will certainly show in pictorial negatives. There is nearly the same highlight contrast, but shadow contrast is much improved. For the same paper scale, about one stop of SBR can be accommodated without loss of effective film speed and in fact with a slight gain, especially when you take into account the points where contrast begins to rise.
I have not found mottling or streaking in my 35 mm negatives. Unfortunately, the smaller negative is favored here because the same extent of constant scene brightness occupies a smaller film area. The developer doesn't know this. The biggest I can go is 5X7, and I will try it when I get the urge.
I do not know how dependent on the developer I used my findings may be. To my knowledge, no one else has tried amidol-isoascorbate developers with 1:100 ratio. Since many of us are using propylene glycol as solvent for stock solutions, it is practical to make a long-lasting stock containing amidol.
I hope you know I meant "one more stop of SBR".
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