My gallon kit just arrived this past week and I can't wait to try it.
It may be pricey, but my understanding of it's capacity and the life of the mixed solution actually seems to make it economical. The cost for the gallon over the quart made the gallon a better deal.
Less expensive developers can turn out to be more expensive in practice. I rarely get through half of my d-76 before it goes bad and must be disposed of. I guess I should just use more film :)
Formula for Diafine
Just in case you weren't aware, D76 lasts MUCH longer than Kodak specs if kept tightly sealed. I've used it out to 18 months with no problems at all but usually don't go quite that long since its also cheap and there's no point risking my film.
I have a litre of d-76 left that is about 9 months old, stored in a plastic water bottle (club soda) with all the air squeezed out. That is actually pretty good for me, as I typically have three litres left in that amount of time. I tend to develop in spurts.
A cloudy precipitate is forming. Last month I'd used some and it was fine, but I was only testing a Bronica GS-1 back I found on ebay. I know it should be okay, but it does make me a bit worried that untouched developer is forming white filaments. Perhaps I should filter and not worry, but I'll use up the rest for testing too (I've purchased three more backs:)).
Soon I will be storing everything in glass, starting with the Diafine. It will make displacing air a bit more complex for developers that need it, but I've decided I like glass better.
A few pointers for Diafine: the speeds they publish on the box are often reasonable starting points but usually a tad optimistic. OTOH, while I know people who claim to shoot films at box speeds in Diafine, I doubt you'll be happy doing so with the films that get the most speed boost - Tri-X being one of the best with this developer. So it's going to take some experimentation, but that's easy enough. It definitely works better (in terms of getting more effective speed) with some films than others. Expect negatives to look a little flat compared to what you're used to. If you're scanning this will be a complete non-issue, if printing optically you may well need to print on a harder paper grade than you're used to but, again, not an issue. It's not going to need a grade 6 or anything, usually grade 3-3.5 works well, but I also print with a condenser enlarger. This can be a good thing with some films and definitely in some lighting.
Be very careful about contaminating any of the A with the B, as they say. The other way (carryover of A solution into B) happens in the course of regular use anyway and is of no consequence. Do not over agitate. I just invert and twist once per minute. You can always give a little longer than the specified 3 minutes as development just goes to completion. Most films are complete in 3 minutes per bath but not all, so if you want to develop different films together and one requires 4 or 5 (per box instructions) just give them all the extended time. You will not see any difference.
The box warns about this too but it bears repeated - do NOT rinse between the A and B.
It's really simple. I occasionally see people asking about "why use this more complicated developer..." or saying they like to keep things simple. Considering the virtual absence of effects from time and temperature variations as long as the minimums are followed this is actually the simplest developer that I've ever used, and I've been experimenting off and on since the late 70s.
I know the ideal way of using two-bath development is to have A in one tank and B in the other, and to move the film from the first to the second. That requires a darkroom; would be hard to do in a changing bag. For those with experience with Diafine: are there any issue that crop up in using one tank, and pouring the solutions in and out? It seems to me that would inevitably increase carryover of A into B, as most tanks always seem to keep a little solution even after you think you've poured it all out. But that reportedly isn't an issue, except that you'd eventually reduce the amount of A you'd have on hand.
No, no problem at all. The only time I've ever used separate tanks has been with 4x5 and my 1/2 gallon deep tanks and hangers (which work fine for Diafine.) For 35mm and 120 I always use one tank and just pour the A back in the bottle and pour in the B. Carryover of A into B hurts nothing (within reason of course.) It's getting any amount of B into A that you have to be careful not to have happen, and it won't in normal use.
It WILL reduce the amount of A solution. The instructions say to add equal amounts of A and B, discarding a little B, to bring up the total. So mix your gallon and divide each solution into two half gallon jugs. As the A solution carries over top it off, then add the same amount of fresh B, discarding a small amount of the used B. Say you need to add 2 ounces of A solution, but your B bottle is still full. Add two ounces of the unused A to top off the working bottle of A, and discard two ounces of the used B and top off with two ounces of fresh.
I haven't been bothering with this, just using it all from a big jug and that works fine too, but that may be why I do eventually have it "wear out" at somewhere between 50 and 70 rolls per quart. Next batch I mix I'm going to do what the instructions say. (In my defense I was introduced to it by a friend in the early 80s and he just re-used it like that, and getting more than 50 rolls through a quart seemed like a bargain. I didn't see much point in the replenishment scheme, and I was using quarts at the time, which were also pretty cheap, about $4 or $5 if I recall correctly.)