jdef said:
I think that the key to these short development times is consistency. As long as I'm consistent, the fill and dump times used for determination of development times will be the same for every session, and constitute an integral part of the process. In other words, the 80 second development time is contingent upon the fill and dump times of the tank used in the determination of that time. If my fill and dump times varied greatly, my results might be less predictable, but they don't. These tanks have very repeatable fill and dump rates, and that's more important than the actual rates themselves, to a point. If these tanks didn't fill fast enough, I might get uneven development, but apparently they do fill fast enough, because I'm getting perfectly even development.
Well, and that's the key, no argument -- if you do it the same every time, and then adjust to get the results you want, you're done fine tuning development and can get on with making pictures.
However -- I'm inclined to think the kind of consistency you need with 80 second development is impossible with any kind of tank other than a Paterson. You can, with suitable graduates and a slight disregard for splashes, fill a Paterson tank in about five seconds; the funnel is large enough you can simply *dump* a graduate containing a full tank load of developer into the top; by the time you can put down the graduate, pick up and snap on the inversion lid, the developer is all in the tank. Additionally, the core of the Paterson ensures that the film is immersed from bottom up, rather than having the developer drip down over the outer edge of whatever film configuration you use after negotiating the slow-flowing light trap of a stainless tank.
It seems me your RUD is likely to give much less wonderful results undiluted for anyone NOT using a Paterson (and likely for anyone unaccustomed to working so rapidly). For someone like me, who finds a nineteen minute cycle relaxing because it doesn't require dumping at a specific second to allow exactly consistent drain time and stop fill, it may not be suitable undiluted.
On the other hand, the fact it works at up to 1:10 suggests it would likely accommodate my habits with a cycle time well over ten minutes at highest dilution -- and of course, like any developer, it's cheapest at the highest dilution that will still develop the film consistently.