Developer capacity, D-23, and dilution

[Ulophot]

Among the accusations ever leveled at me, exhibiting a command of math and chemistry are not to be found. I'm running a series of tests with D-23, from N+2 to extra-compensating, in both tray and rotary tank (Jobo on a Uniroller). I'd like to be sure I'm not introducing an unrealized variable in my dilutions. My weekly available time for photography, at present, is constrained.
D-23
D-23 capacity, straight, is listed at the equivalent of 16 4x5s per liter (4 8x10s, 320 sq. in.). My question is the minimum amount of this stock solution required when it's diluted; I've been unable to find a clear answer. Specifically, I would think that a liter a working solution of 1:1 would then process 8 (one-shot), one of 1:2 would process 4 and one of 1:3 would process 2. Therefore, my logic runs, a could process only 1 sheet in a half-liter of 1:3; that would be 4 ounces of stock in that working solution to process a single 4x5 sheet. Is that right?
What I have seen often in posts on various sites, is suggestions like, "Well, I would double the total working solution at that dilution, to avoid early exhaustion..."
Since my calculation methods are not infrequently flawed, I will grateful for any scientific correction.

[Jim Noel]

The minimum amount of stock solution required is the same whether straight, or diluted. If less is used there is a great chance of under-development due to developer exhaustion.

[Sal Santamaura]

The minimum amount of stock solution required is the same whether straight, or diluted. If less is used there is a great chance of under-development due to developer exhaustion.

Concisely, eloquently correct. No further elaboration required or equivocation appropriate. Great work, Jim!

That post ought to be put on the home page.

[xkaes]

You've got the general idea right -- as you dilute the developer you need to increase the time. A good starting point, is DOUBLE the dilution, DOUBLE the time. But that only goes so far, as mentioned. Developers wear out -- AKA exhaust. This happens sooner as the developer is diluted -- AND it will impact the highlights and shadows deferentially, so the contrast will change. But whatever dilution you use, for however long, you need to run tests to examine the film speed and the contrast.

[Tim Meisburger]

Right, but I develop 4 sheets with about 250ml all the time. When I was shooting Shanghai, I used to develop four sheets with 80ml, but that was definitely not enough for FP4. So, my guess is that different films will require different amounts of developer, but that is just a guess...

[LabRat]

D-23 is to be used straight, as it gets too weak for normal Dmax when diluted (even at extended time)...

Steve K

[Ken Lee]

D-23 is to be used straight, as it gets too weak for normal Dmax when diluted (even at extended time)...

That hasn't been my experience. With regard to contrast curves and film speed, my D-23 1:1 images are basically the same as those I have made with D-76 and Pyrocat HD at comparable dilutions. To prove this to myself I did a rigorous BTZS test of HP5+ and compared the curves with those from D-76 and Pyrocat HD: they were virtually interchangeable. One test like that was convincing enough for me.

See http://www.kennethleegallery.com/html/tech/D-23.php for a few sample images.

[Joe O'Hara]

That hasn't been my experience. With regard to contrast curves and film speed, my D-23 1:1 images are basically the same as those I have made with D-76 and Pyrocat HD at comparable dilutions. To prove this to myself I did a rigorous BTZS test of HP5+ and compared the curves with those from D-76 and Pyrocat HD: they were virtually interchangeable. One test like that was convincing enough for me.

See http://www.kennethleegallery.com/html/tech/D-23.php for a few sample images.

Seconding Ken here. I use D-23 1-1 all the time and have no problem getting all the contrast I can stand, and that's using a diffusion enlarger and Ilford MG Warmtone, which is softer than MG Classic. FWIW I run everything at 70 F because I'm too cold in a 68 F room.

Also, I always use 100 ml of stock D-23 per sheet of 4x5; overkill maybe but developer is cheap at the volumes I use it. So 4 sheets of 4x5 in a Jobo 3010 tank takes 800 ml of diluted solution. Also I mix and dilute with distilled water.

[Kirk Gittings]

That hasn't been my experience. With regard to contrast curves and film speed, my D-23 1:1 images are basically the same as those I have made with D-76 and Pyrocat HD at comparable dilutions. To prove this to myself I did a rigorous BTZS test of HP5+ and compared the curves with those from D-76 and Pyrocat HD: they were virtually interchangeable. One test like that was convincing enough for me.

See http://www.kennethleegallery.com/html/tech/D-23.php for a few sample images.

were you doing a pre-soak in that test?

[Ken Lee]

were you doing a pre-soak in that test?

Yes. I always use a 3-5 minute pre-soak.