From: Sandy King (sanking@clemson.edu)
Date: 12/04/02-09:08:53 AM Z
My thoughts on this.
1. I have never tested Ilford Delta 400. It is possible that results
from this film are different from other films I have tested, which
include TRI-X, HP5+, FP4+, and Kodak T-100 and T-400. However, I
think it unlikely that the results would be different enough to
account for the speed loss you describe.
2. You are using the recommended formula and would gain nothing from
changing the accelerator from potassium to sodium carbonate, or to
hydroxide. However, even if using the right formula it is *possible*
that a mistake was made in mixing the chemicals.
3. In all of my tests Pyrocat-HD, either at 1:1:100 dilution or
2:2:100 dilution, has delivered at the very least full emulsion speed
as rated by the film manufacturer, using as a standard D76 1:1 as the
comparison developer. In fact, in most situations there was a slight
speed gain with Pyrocat-HD in comparison to D76.
4. The problem may be a conceptual error in your testing procedure.
Simplify it. First, make a test by exposing two sheets of film in a
real-life situation, developing one in ID-11, the other in Pyrocat.
Use Pyrocat at 1:1:100 and develop for the same time you would for
PMK 1:2:100. Then print the negatives and compare the prints. Don't
expect any dramatic differences at normal print sizes. Try 10X-20X
enlargments of small sections of your negatives to appreciate subtle
differences between the two developers.
5. For a more comprehensive testing system that really works I
recommend the procedure described by Phil Davis in Beyond the Zone
System. You should use a color densitometer in blue channel to read
negative densities. It will not be possible to get much of an idea of
the real printing density of a stained negative by reading the
step-wedge densities with a B&W densitometer.
Good luck, and let us know what results.
Sandy King
>Hello all -
>
>I'm hoping someone out there can help with my problem.
>
>Problem:
>After reading "The Book of Pyro" and visiting www.unblinkingeye.com,
>I recently switched from Ilford ID-11 film developer to Pyrocat-HD
>with the hopes of getting negatives that have better tonal
>seperation, are sharper, and have less grain. I am currently
>performing film speed tests with Ilford Delta 400 (4x5) which I will
>use to create enlarged negs (via Liam's reversal process) for
>contact printing. I believe that I am getting excessive general fog;
>causing extreamly slow film speed results.
>
>Processing:
>I chose 15 minutes as a starting time and tray developed (with
>gloves) at a dilution of 1:1:100 (see below for formula); agitating
>for 15 sec. every minute. I used a water stop (2 min.) and fixed (2
>min.) in TF-3 Alkaline Fixer without Sod. Sulfite. I then returned
>the film to the developer for 2 min. without a rinse, washed for 20
>min., and dried.
>
>Having a B&W densitometer, I could not get an accurate density
>reading from the stained film. Using the process for estimating
>negative density without a densitometer found in the Ansel Adams
>Guide : Basic Techniques of Photography, I did the following:
>
>1. Print a very light tone using a unexposed, undeveloped piece of
>film cleared in fixer. I used the densitometer to measure the
>density of the print which I recorded along with the time (A) to
>make that tone.
>
> 2. I then printed an unexposed piece of film developed in
>Pyrocat-HD to the same tone as in step 1, using the densitometer to
>ensure the density of the print matched that the original. Again, I
>recorded the time (B) to make that tone.
>
>3. Next, I printed a piece of film exposed for Zone I and developed
>in Pyrocat-HD to the same tone as in step 1, using the densitometer
>to ensure the density of the print matched that the original. Again,
>I recorded the time (C) to make that tone.
>
>4. Finally I divided the times B & C by the time A to come up with
>the ratio for steps 2 & 3. I then compared the ratios for steps 2 &
>3 against the Exposure-Density chart.
>
>What I came up with was that the density for base+fog (neg in step
>2) was approximately 0.22 and the density for exposure (step 3) was
>approximately 0.24. Assuming I need a density of 0.10 above base+fog
>for zone I, I would have to rate my film at EI 100 for a 400 speed
>film (a loss of 2 stops).
>
>Question:
>The newer version of Pyrocat-HD uses a 100% soln. of Pot. Carbonate
>- the older version used a 10% soln. of Sod Carbonate. Per Anchell's
>The Darkroom Cookbook, Pot. Carbonate is stronger than Sod.
>Carbonate - needing 0.90x the weight for subsitution. According to
>The Book of Pyro, pyro combined with a strong alkali (higher
>ph)increases base fog. Should I revert to the older formula? I also
>read that Ed Buffaloe (unblinkingeye) used a 10% soln. of Sod.
>Hydroxide (even higher ph). Does a 10% soln. of Sod. Hydroxide have
>a lower ph that a 100% soln. of Pot. Carbonate?
>
>Plea:
>Pleasssssssse, somebody set me straight. I will have to go back to
>ID-11 (sigh) if I can't straighten this out. I want it all - better
>tonal seperation, sharpness, and less grain at somewhere close to
>the manufacturer's ISO/ASA.
>
>Thanks in advance from a newbie,
>Scott Wainer
>
>
>The Pyrocat-HD formula I use is:
>
> Stock Soln. A
> Sod. Bisulfite 1 gm
> Catechol 5 gm
> Phenidone .2 gm
> Pot. Bromide .2 gm
> Distilled Water to make 100 ml
>
> Stock Soln. B
> Pot. Carbonate 100 gm
> Distilled Water to make 100ml
>
> Diluted 1:1:100 with distilled water
>
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