Rod, Never having heard of OA developer, I looked on digital truth and found HP5 to be the only film listed for obsidian aqua
. Can you (or someone else) give "us" some more info on it and its qualities? Thanks, Bill
Certainly.
OBSIDIAN AQUA is another developer invented by Jay DeFehr. It's a compensating developer with similar behaviour to an earlier Jay DeFehr developer, 510-PYRO. Like 510-PYRO it lasts indefinitely but unlike 510-PYRO it is not a syrup but is two solutions that are mixed with water just prior to use.
I have found if I expose for shadow texture on Zone III then use a semi-stand regime for agitation that I get a nice spread of tones with good protection of the highlights. It can be used to develop different films with different ISO ratings, all together, in the same tank, at once.
Here are two sheets covering how I use both 510-PYRO and OBSIDIAN AQUA.
http://freepdfhosting.com/3e906fe75d.pdf
You will see that there are no changes to time, temperature or dilution regardless of the film. This seems weird at first but it has never let me down. So far I have used it with 9 different film types: ADOX CHS 25 ART, ADOX CMS 20, FOMAPAN 100, FOMAPAN 200, ILFORD Delta 400, ILFORD FP4 Plus, ILFORD HP5 Plus, ILFORD PAN F Plus and Rollei RPX 25.
Here is a link to the results of a search on Flickr for photographs developed in OBSIDIAN AQUA by various folk.
http://www.flickr.com/search/?q=OBSIDIAN AQUA
Come back to me if I can be of any further help.
RR