Alright. My recent testing of HP-5 in the Jobo a the 2:2:100 dilution at 73 degrees and the slow rotation gives me the following times for a target DR of 1.05:
Normal (SBR 7) EI 250 - time 6 minutes
Normal +1 (SBR 6-) EI 250 time 10.5 minutes
Normal +1.5 (SBR ~ 5.5) EI 320 16 minutes
Notice that I don't have any N- times at this dilution. It is just too strong. My guess would be that an N-1 could be achieved at 4 minutes, but I didn't run any times this short. If you are only doing silver, I think I would use the 1:1:100 dilution, unless you are faced with a serious N+ expansion situation. Sandy might have some better information on the proper times for this dilution.
And about the Houston/Galveston area, sure. I have to check with the ruling authorities and so forth, but I would definitely like to get out early before the heat and humidity gets truly murderous. Email me off list and we'll see if we can work it out.
For silver printing I would also recommend the 1:1:100 dilution of Pyrocat-HD. Unfortunatlely I can't provide any data at this time about the combination. I am in the midst of a major renovation project on my computer room/library and my main computer is down and all files and books from the room are temporarily scattered in the three adjacent rooms.
Without try to be contentious, I've been contemplating the idea that "*No* development should ever take less than five (5) minutes, because it will be uneven."
Originally Posted by clay
I've done a few hundred, or so, rolls of C41 color, where the usual color development time is three minutes and fifteen seconds ... and although I've certainly made my share of boneheaded mistakes, I cannot say that "uneven development" was ever a problem. Likewise, in reading "Worlds in a Small Room" by Irving Penn, I've noted that,
"Most of the photographs in this book were taken on Kodak Tri-X film. The only exposure records for which I have an accurate record, the pictures in New Guinea and Morocco, show that Tri-X was exposed at 160 ASA, or at 80 to 125 ASA for very dark skins. Development was usually in UFG, 3 to 5 minutes at 68 degrees F."
- Irving Penn, "Worlds In a Small Room", Notes, page 92.
So, being of a questioning nature - I'm wondering about the the reasoning behind the "No less than five minute rule", propagated by Kodak, Ilford, Agfa ... and just about everyone else - and so readily *broken* by Irving Penn.
I *may* just choose to ignore this rule altogether in the future.
Ed Sukach, FFP.
I don't think there is any real technical reason that 'shorter than 5 minute development times' will not work, but it seems more a practical one of how consistent you can be at timing and stopping development. A 20 second variation at 6 minutes is a 5.5% variation. The same timing error for a 3 minute time would be 11%. If you are tray developing and using and acid stop, I imagine your potential timing error would be small.
As an aside, there was a thread on the Bostick and Sullivan alt-photo list a few months ago about using amidol as a developer for platinum negatives (Terry King says this is what Frederick Evans used). His times for FP-4 were about 2 minutes if I remember correctly! So if you're in a hurry, there you go!