Many years ago I built a 16" X 20 " field camera and experimented with using 16 " X 20" generic ortho film from Freestyle instead of regular panchromatic film because it was cheap and because it looked a lot like 19th Century film when processed for continuous tone. (Blues are rendered lighter in tone, reds dark, and it is so slow that you end up with time exposures even in bright sunlight.) The film manufacturers all refused to advise me, saying that high contrast film was not intended for continuous tone and they wouldn't guarantee the results. But by trial and error, and months of experimentation, I found a method that worked well.
Testing the development and exposure by printing and not by eyeballing is essential because the drastic dilution changes the color of the film to a muddy brown--what looks to the eye like a very flat negative actually prints on photo paper with much more contrast because of the change in color, which is similar to the color of a safelight. The film speed is also extremely slow, about ISO 1.5 instead of 6, because you need shadow detail if you're trying to avoid high contrast. Even development was another problem with such large negatives. I settled on using a Dev-Tec color print processing tube with constant rolling agitation, reversing direction every 30 sec. Keep in mind "expose for the shadows, develop for the highlights" and print on photo paper to evaluate exposure and contrast (minimum exposure time for maximum black of the clear edges of the film). Increased development increases contrast, decreased development softens contrast. Development is affected by: 1. Time (the longer the time the more the development) 2. Dilution (the stronger the concentration the faster the development) 3. Agitation (the more agitation the faster the development) 4. Temperature (the warmer the developer, the faster the development) I ended up with something like 1/4 oz HC110 concentrate (straight from the original bottle, not diluted into stock solution like Kodak recommends, in 32 to 40 oz water at 70 degrees F for a development time of about 5 1/2 to 6 1/2 minutes. My students have achieved similar results using 35mm Kodalith film, resulting in 35mm negatives that are so fine grain that they almost appear to be large format. Try to keep your development time to 5 minutes or longer for even development. Bracket your exposures and development to find the best kind of detail and contrast. Its slow and unconventional, but it does work and can create a beautifully delicate tonal range that takes full advantage of all the blacks, whites and middle tones afforded by your paper if tested and handled carefully. Good luck. Best, Rick Dingus > From: Gene Johnson <[EMAIL PROTECTED]> > Organization: @Home Network > Reply-To: [EMAIL PROTECTED] > Date: Mon, 15 Oct 2001 11:00:57 -0700 > To: cameramakers <[EMAIL PROTECTED]> > Subject: [Cameramakers] industrial films > > Hello Cameramakers, > > I was wondering if anyone has had experience with using any of the Kodak > or other large industrial films like precision line film or reproducing > film in their large format cameras. I see this stuff as surplus from > time to time, and was curious about it. I know these are generally > ortho films, and I have no experience with that. Will I be able to > develop it with ordinary developers? Also, I just bought a huge roll of > Aerial reproducing film, Kodak SO-192 for just about nothing. It's 5" > rollfilm and I've also just bought a 5" rollfilm back to use it with. > Since there are no available tanks to develop it in, I'm hoping I can > modify a multi-roll Jobo tank to allow me to develop 6 feet or so at a > time. I also hope I can "reverse engineer" the back to see how hard it > would be to make approximate copies. > > > Gene Johnson > _______________________________________________ > Cameramakers mailing list > [EMAIL PROTECTED] > http://rmp.opusis.com/mailman/listinfo/cameramakers _______________________________________________ Cameramakers mailing list [EMAIL PROTECTED] http://rmp.opusis.com/mailman/listinfo/cameramakers
