Problems calibrating XTOL+TMYgreenspun.com : LUSENET : Large format photography : One Thread
Here's a slightly different tack on the "what's going on with my XTOL" threads.
Initial Zone I, V, and VIII exposures developed in a 1:1 dilution showed a realized EI of 400, but with densities of V and VIII ~0.1D and 0.3D+ too high, respectively (measured on the cheap with a Pentax spotmeter in what should be a fairly linear region for the meter).
I repeated the Zone I, V, and VIII exposures, but added exposures up through Zone XII for laughs. Reduction in development time by about 15% still gave Zone I density of ~0.1D above fb-f (measured to the effective 0.1D resolution of the spotmeter), still too high contrast up through about Zone VIII, then a profound flattening of the curve through Zone XII, with the higher zones increasing in steps of about 0.1D.
Did I just cut off development early enough that the higher zones didn't get enough development time? Shouldn't some extremely high zone placing still reach D-max? Could it just be too frequent agitation combined with too short development time? I believe my procedure is repeatable, I'm using enough stock developer, I'm agitating every 30 sec. with a several minute presoak, and no, I haven't tried distilled water yet.
-- Rick Koo (email@example.com), July 31, 2000
Agitation every 30 secs? Yeah that will give you a large contrast range. If the paper can't see such low and high zones, then why use them to calibrate? Especially with such a non-critical measuring system? I discarded the spot meter w/50mm lens on backwards. It is not critical enough as a densitometer. People who use them and claim success are few and far between. Go to a lab and have them run some calibration on your negs. And concentrate on Z's 3-8. That's where the action is. Give a little more exposure and less agitaion. And remember that Tmax films look different than the normal films you are probably used to. They look thin but printing is the true test. Calibrate your film to the paper you are using. Test your film and print the negs. That's the true test. It will change from paper to paper and film to film. But calibrate to your materials and not a makeshift densitometer. You will get more out of it in the long run and better results consistently. james
-- james (firstname.lastname@example.org), July 31, 2000.
James just gave you some very good advice. You should always use distilled water as it eliminates all the variables that can happen with tap water, last switch to Tri-X film. Regards, Pat
-- pat krentz (email@example.com), August 01, 2000.
I can't really add anything solid other than the fact that TMY is notoriously touchy in the soup, especially in the N- region. Those steps can sometimes be 30 sec. apart. There are some H&D curves and soup times on my website that you might find interesting. http://members.home.net/brucewehman
-- Bruce Wehman (firstname.lastname@example.org), August 03, 2000.
I want to echo the previous point. I develop TMY in ID-11 1+1; N is 7.5 minutes, N-1 6.75 minutes, N-2 6 minutes. I develop in a Jobo with constant agitation. I also do not use a pre-wash. I seem to recall reading somewhere that it is not recommended with TMY but I can't remember where I read it and it could have been for rotary processing only.
I would also agree with getting your negs through a proper densitometer. If you are going to go to all the effort of testing then why use a makeshift device?
Please let me know how you get on with TMY and XTOL, as I am considering switching to this combination!
-- Andrew Herrick (email@example.com), August 15, 2000.