If you’ve ever processed sheet film in open trays, you’ve likely come across the same problem I had: negatives get scratched if you try to process more than one at a time (I’ve read that it’s possible to do, but I’ve never been successful). The temptation was always there, though, because processing one negative at a time is deadly slow. With my one water bath (the bathroom sink), I couldn’t presoak negatives at the same time I was washing processed negatives, for fear of contaminating the unprocessed film with fixer. Processing a sheet of film was taking about 30 minutes — now multiply that by a reasonable 5-15 shots from a day’s shoot, and processing film became a very daunting prospect, to the point that I still have some film in holders from more than two years ago that needs to be processed.
Looking into alternatives, I had read about the BTZS tube processing system, but it seemed expensive, and like more of a commitment than I was willing to make given how infrequently I process large format film. However, I came across another idea recently, and decided to give it a try: open-tube processing. The idea is not that you enclose the film and chemistry inside the tube for daylight processing, but rather that the tube is just there to keep the sheets of film from rubbing up against each other and scratching the emulsion as they’re processed in a darkroom. I acquired a piece of 2″ PVC drain pipe (about $8 at the hardware store), and cut it into four 7.5″ long pieces (with lots left over), drilling a few holes around the perimeter of each tube to see if I could avoid the water mark reported in the article where I’d first read about doing this. The holes are almost certainly superfluous, but they’re there, and they’re not hurting anything.
In any case, I recently processed ten sheets from Thanksgiving. It only took about two hours, which is a huge improvement. Processing is exactly like normal open-tray processing, but you fit the film into the tubes (emulsion facing inward) before the presoak, and I found that trays intended for 8×10 processing (actually about 12×10) are big enough to fit four tubes at a time. The tubes are transferred between trays like you’d expect, though I now use 100% agitation, rolling tubes against each other, to ensure even chemistry coverage. The only trick beyond the actual using of tubes that I’ve discovered is to shift each piece of film around inside its tube while in the water bath, so that there’s a thin film of water between the sheet and tube; this avoids the water mark. Once the film slides easily in its tube, you’re golden.
Of course, this speedy processing of film means that I can discover much more quickly just how much I have to learn about shooting with the 5×7 camera — I tried some fancy focal plane shifting tricks for these shots, and only some of them worked. The pictures were exposed and developed perfectly, but the focus… ugh. Some are better than others, but suffice to say that shooting large format is sufficiently different from shooting with an SLR or rangefinder that I can’t consider myself proficient yet. With everything zeroed and flat, I’m fine, but using swings and shifts? Lots to learn.
Must be time to go shoot some more 5×7, and get some learning done!