N+ and N- times for Pyrogreenspun.com : LUSENET : Large format photography : One Thread
I am currently developing 4x5 negatives of Tri-X Pro Pan (rated at 200) and Bergger Pan (rated at 100) in the Leban ABC Pyro formula in a Jobo Expert Drum. Normal development runs between 7-1/2 minutes and 8 minutes. I would appreciate any suggestions regarding N+ and N- times for these films. Thank you.
-- Mark Lipton (email@example.com), September 15, 2000
You say that you are using Tri-X Pro Pan by which I take it that you are using the Tri-X nominally rated at 320 by Kodak. If this is the case then, depending on the type of photography you do, there could be some significant pitfalls. Unless this film has been redesigned and reformulated it is recommended for studio use only, and if used outdoors could offer some serious problems depending on the lighting conditions. Most people buy the pro films because of the short dating and and what is supposed to be optimum aging. The fact is that Tri-X professional is designed for studio use in extremely controlled lighting conditions, and it has no anti-halation backing. Used outdoors on bright, or even cloudy bright days, there can be significant light scattering in the emulsion which can impact your controlled development and contrast methods. Having said that, I have used the film for many years and like it a lot, but I do not consider it to be the best film for many lighting conditions. There is also the possibility that the film you are testing is different from what was previously available to me. In that case you are on your own here and I wish you the best of luck. I know absolutely nothing about Bergger film, so I am an empty fountain of knowledge there. See if you can get some Kodak Ektapan (ei 100) and try that out. I used this film a lot and really liked it. Don't remember how I rated it because I quit using light meters many years ago. Find a film/developer combination you like (and I used D-23 split and loved it) and stay with that.
-- fred (firstname.lastname@example.org), September 15, 2000.
Don't concern yourself too much with the alluded to inflexibility of Tri-X in 4x5 size. Ansel Adams and countless other photographers of merit (myself modestly included) use(d) Tri-X Pro 4x5 outdoors, (which, incidentally, is not the same film as Tri-X Pro in roll film formats), with excellent results. If you understand your film/developer characteristics, you can use it under just about any lighting condition. Tri-X has proved itself to be a great "general- purpose film" (to quote Kodak). As to your original question, I can only say that the individuality of approach and equipment combinations precludes any definitive determination of N+ or N- times. You need to test for yourself. If you don't have a densitometer (I don't either) I suggest you get a copy of "The New Zone System Manual" by Minor White, Richard Zakia, et al. and review their suggestions for Zone system calibration. I have found this approach to be quite accurate, useful and quick once you get the hang of it. Regareds, ;^D)
-- Doremus Scudder (ScudderLandreth@compuserve.com), September 16, 2000.
Mark, The preceding comment by Doremus Scudder is the best advice. Test for N- and N+ yourself.Recall that you cannot easily use a densitometer to interpret the results due to the staining. However, some writers suggest that Tri-X and other films of its type,meaning non T-Max or Delta, require for N+ a 30-40% increase in normal film development time + plus a 1/2-1 stop decrease in exposure. For N-1 the development time , the normal development time should be reduced by 30-40%, and the exposure increased by one stop. Gordon Hutchings suggests the following for Tri-X: (N=14 min), (N+1=20 min.), (N-1=11 min). But that is assuning an E! of 260 AND the use of his PMK developer. Hope this helps. Bob
-- Bob Moulton (email@example.com), September 16, 2000.
I have tested HP-5 plus for the zone system with D-23 and D-25. With both developers, each change of 1 zone in development needed a 1/3 stop change in exposure: N-1 needs 1/3 stop more than N; N+1 needs 1/3 stop less than N. N-1 required a 15% reduction in developing time, N-2 required a 30% reduction, and N+1 required a 60% increase. You might use these (or Bob's) suggestions as a guide.
-- William Marderness (firstname.lastname@example.org), September 17, 2000.