If you keep adding more and more phenidone and no more A. acid, the
shadow density will increase, that according to your previous remark.
Perfection XR-1 is film developer with very high levels of phenidone and
fractions of it's amount of hydroquinone and metol. Substituting A. acid
for the hydroquinone may boost shadow density even more.
XR-1 is noteworthy for the two to three stop speed increase
it provides. Dan
Why is density on the left and why the negative values for exposure. Dan
If you believe that, try it and report it to us. I did not get that from my previous post. I have not found any developer that would give me increased shadow density without also giving me increased contrast. True there are certain developing agents that are more efficient than others, but sticking to a given pair won't buy you much in that regard.
The density scale is always on the left unless you put it on the bottom. The negative values are because the scale is "Log of relative illumination." I have not the wherewithal to measure absolute illumination. All test film strips were on the same roll of 35 mm film, exposed in the same way at the same time. In any case, the relative exposures are always smaller to the left, so if the largest log is 0, the smaller ones will be negative.
Any strip from that roll of film would give me the same intercept at the left end of the scale from any developer I have. The contrast would vary with time of development or concentration of developing agents. I chose to hold phenidone constant for these tests. If I change phenidone concentration and went through the same variation of ascorbate, I would get a different family of curves, but all would still emanate from the same point.
I used that developer years ago. In those days it gave a speed increase, but no more than everyone was getting. The films were rated much lower in speed than the same film would be now because the ASA ratings were not used by the ISO. I also tried Acutol, in spite of the ridiculously impossible curve shape they touted to show "compensation". It was OK and still is, but PC-TEA is capable of duplicating the curve shape. I have done the comparison.
Originally Posted by dancqu
Repeating one of my posts at photo.net:
I made a version of PC-TEA with twice as much phenidone and called it 2PC-TEA. At 1:70, 76F, 9 minutes, it gave a contrast index of 1.2 on Delta 400, and a true speed of perhaps 640. This is a bit better than I would get with PC-TEA. Grain is not great, but not very objectionable either. Some of the sharpness of Delta 400 is lost. I also tried 1:100 at 10.5 mins at got a ci of 1.1 with a touch more shadow speed.
I tried 2PC-TEA 1:100 on Tri-X as well, but this time with two tbsps of sulfite per liter. At 76F, 8mins, it gave ci of 0.9 at a staggering speed, probably 800 ASA. Full developed to a ci of 1.2, the speed is going to be whopping. The grain is quite big for Tri-X, but sharpness is not too bad.
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Now what do you do with a contrast index of 1.2? Somewhere around 0.6 is normal in my darkroom. If you reckon film speed by density above B+F, it varies with C.I. but if you reckon it by the point where local contrast gives usable shadow detail you get less change with contrast. I do not usually mention film speed because I do not have the apparatus to be sure I know what I'm talking about. I set my exposure meter according to "box speed" when I make my test exposures.
The difference between 400 and 640 is about 2/3 stop. Acceptable manufacturing tolerance is 1/3 stop give or take. The box speed is supposed to be the nearest 1/3 stop to the actual speed. What do we argue about? I went through all this years ago because I was taking pictures on stage at orcheatra rehearsals and wanted the max. I found more effect of meterings than of any other source of variance in the results, and I tried just about every highly touted speed developer on the market. I finally settled on my own concoction of phenidone, hydroquinone and sulfite and setting the on-stage exposure at 1/60 and 2.8.
The digital age has taught me a lot about shadow detail. I have some negatives I cannot print any other way. They are so thin that the only way you see the image is by glancing reflected light as a positive. You all have seen such disasters, I'm sure. I know the shadow detail is there because my scanner told me so. As far as I know, no one makes grade 10 paper, but my scanner and software make it aout of typing paper. Don't get me wrong. I'm not a heretic. It's only for those pictures I must have that I resort to such reprehensible shenanigans.
Some of those thin negs have been rescued by intensification through bleaching and redeveloping in a pyro developer. The silver image is restored and a stain image is added to it.
I wander as I wonder.
I should have said this before I wandered. Show us the family of curves for several different developing times so we can guess how much of the speed increase is due to contrast increase. Also, my film was HP5+ and was shot at 400 by my meter, which may or may not be accurate.
Originally Posted by psvensson
I'm sorry, the figures aren't contrast index. It's zone VIII density minus zone I density. I aim for a range of 1.25 for a diffusion enlarger.
I know, measuring shadow speed is iffy, and my results can be regarded as anecdotal. But they're shot with the same camera and I find the results fairly consistent. There's nothing to say that you will get the same density I do when rating a film at a particular speed, but I feel fairly confident that increasing phenidone increases shadow speed. Especially in the case of the Tri-X test I mentioned above, there was almost a 2-stop increase in speed as compared to straight PC-TEA.
I wish I had some tables to show, but as you can see from my latest post, the films were not developed to high contrast. In fact, the contrast on the Tri-X test was lower than recommended even for condenser enlarger. I'd probably have to print it on grade 4 on my diffusion enlarger.
Originally Posted by gainer
The use of CI when zone VIII is meant has had me wondering and
Originally Posted by psvensson
Mr. Gainer off on a tangent.
I don't understand Mr. Gainer's questioning your results. After
all PC and TEA are to some extent his babies.
I've two issuses of Darkroom Techniques from the early 80s
which extol the virtues of Perfection XR-1 and it's speed increasing
abilities. Why fight it. At www.unblinkingeye.com they have
a good article on XR-1. Three agents are used but maybe two
Your ph may be a bit high. You've mentioned perhaps more grain
than will result from a lower ph solution. Dan