professional duplicating filmgreenspun.com : LUSENET : Large format photography : One Thread
hi kodak makes a professional duplicating film and a kodak rep told me recently that it was soon to be discontinued. i know i may be needing some - probably after it is gone - so i am kind of searching for another source. has anyone used direct positive film that photo warehouse offers? it *seems* very similar, if you contact a negative, you get a negative, and positive contacted yields a postive, but i haven't bought any and done tests with it. if this film turns out to be totally different, can anyone suggest any other film i might use to make dup. negatives? thanks in advance! - john ps. happy thanksgiving!
-- john nanian (email@example.com), November 22, 2001
i'll post my results when i buy some of the film. it might be a while .. john
-- j nanian (firstname.lastname@example.org), November 25, 2001.
John, if you're referring to SO-132, Professional Duplicating Film...it was going to discontinued last April, but it was given another a year..... it's a unique product, although Fine Grain Positive film may be the other one you're referring to??
At any rate, I've used a fair bit of SO-132 to dupe old negs, and have gone over to a 2 step method now in light of the film being discontinued. The 2 step method is preferred for the control over the final working neg (from original--interpositive master--working neg), and this is the method that is actually used by the majority of archives and similar places. SO-132 has a really odd curve, that is not a very good match for old negs, although newer emulsions (if the contrast is right) seem to work fine. I've had a few problems with it, although I have to print alot of older dupes at work off the predecessor to this film--SO-336-- which WAS a terrible film, and had bad storage characteristics resulting in the film itself not lasting long. It is for this reason that SO-336 fell out of favor with institutions and coupled with it's truncated tonal repsonse, it really wasn't used by alot of people.
You can still find SO-132 here in the US, it's still in production, for a while anyways...it's expensive, it runs about $45 a 25 sheet 4x5 box. I stockpiled a small amount of several years ago, but have really gone over to using a film like Delta 100 or Plus-X to make my interpositive, either by projection or contact, and then contact that sheet onto Ilford Ortho + film as the working neg. The advantages to this are numerous, because you can use a panchromatic film as the interpos step, to filter out stains etc....and you can get into dodging, burning and masking as well. The interpos becomes the master, and then you can make as many working dupe negs off this as needed...
Agfa made a direct pos dupe film, I think n330P, but that film is long-gone . Bergger has some technical lab duplicating films as well, but these are not direct positive, at least not the ones I know of.
If you do find some SO-132, it's a slow ortho film...the speed is about the same as Azo. I used an old multiple bulb, contact printer with a voltage stabilizer as my light source. I ran the film through deep tanks using replenished DK50 as my developer. It's important to follow Kodak's instructions with this film, and to not use a hypo clearing agent...but to use a full wash. Then you either brown tone the neg or use a strong selenium toner with it as well and rewash. For more info on neg duplicating, check out Kodak's "Copying and Duplicating in Black and White and Color" Pub. #M1.....most of the films listed there are discontinued now....such as Commercial Film, but Ortho Plus is similar....or you could just use Ortho Plus for both steps, if you didn't need the panchromatic response....good luck either way.
Opinions expressed in this message may not represent the policy of my agency
-- DK Thompson (email@example.com), November 26, 2001.