Processing 35mm long rolls
This is a question of historical curiosity.
A post today by DrZorba of a Nikon with a huge 35mm bulk back took me back.
I got my first OM-1 in the late '70s. I was a high school student, so I had little money for accessorizing, but I buried my nose in the accessory catalogs that came with the camera, and I daydreamed about every entry. (Part of me still wants an Olympus microscope, and I can't say why.) I thought the bulk film backs were very cool. (I don't recall in what context I imagined I would need them, but that's what daydreams are like.)
Anyway, if you actually shot a 250 frame roll (or for DrZorba's post, 750 frames), how would it even be processed? Is this something that would get multiple loops (for lack of a better term) in deep tanks, or would it get cut up, assuming that you could sacrifice a few frames?
I don't personally know (haven't done any bulk loading back work)...
But I imagine any system designed to do movie film processing, could handle the job.
The big labs I'm familiar with ran cine processors. They're continuous machines, preloaded with plastic leader material. You start up by tape-splicing the front of the film to the end of the leader. When you run out of film, you attach a roll of leader to the tail end of the film, so the machine automatically restrings itself with leader. Obviously this is only sensible if you have quite a lot of film. Our last machines ran 50 ft/min, so that 250-shot roll would only take about 40 seconds of machine time.
For smaller quantities, there were roller-transport machines, such as the Kodak Versamat. With these, you could attach the front end of a film roll to a stiff plastic card, which then "leads" the film through the processor. This is the same way modern mini-lab processors work. Your film could be essentially any length you want.
I know that large reels were available for manual-type processing, but never worked with that sort of thing (beyond standard Jobos)
Yes, you're right. Each tank has a "rack" which has a set of spools on both top and bottom. The film enters over one spool, then multiple passes up and down in a helical wind pattern and exits from the other side of the rack. You spool the emulsion side out, so it virtually never has to contact anything.
Originally Posted by DLawson
If you didn't have these multiple loops, the machine would need a very slow speed, comparable to a mini-lab processor.
Some frames will be damaged, but when I have done that I just load each processing reel then cut the film and load the next reel. You have to weigh the time spend procuring long roll film, loading the back and processing it with the convenience of using conventional 35mm canisters. Sure, a lot can happen with your subject in the seconds it takes to re-load a 35mm canister in the camera, but what happens when you reach frame 250 of the long roll? These are the questions I have asked myself whenever I see those long roll backs that I lusted for in my youth.
Last edited by ic-racer; 07-14-2013 at 12:57 PM. Click to view previous post history.
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Nikor made long-roll reels and tanks that would handle the 33ft (250 exposure) or 100ft (750 exposure) rolls from these bulk backs. They were made for field processing of 50 and 100ft movie film but 35mm is 35mm.
I've shot a lot with the 250 back for the original F-1 and the FN-100 back for the newer F-1 and when doing slides it was just a matter of finding someone who did roller transport processing instead of dip n dunk. The last place I used was E-Six labs in Atlanta but they're gone now :-(. I have a big Jobo reel and tank that easily handles the FN-100 rolls...so far I've just been hand inversion processing with it by removing the cog and using an orange cap, but I have a big ATL machine that I plan to use for slides once I get it set up.
Swapping rolls when you hit the end does take a bit longer than with normal 35mm canisters but on the upside there's no rewinding! And a huge benefit overall is there is no felt light trap - the film is just moving through air once the canister is opened up when inside the back.
In the 1980s, I was employed by a security firm where I installed and maintained surveillance cameras in almost 100 locations, mainly banks. I had between 250-300 of these cameras that took 100 foot rolls of 35mm film. We bought 100 Ft. Tri-X by the case! Until my employment, the company had film processed by a local lab that had one of the machines mentioned in posts above. I talked the company into building me a darkroom to save money. While I would have preferred to have the large reels that would hold 100 ft., that seemed too expensive, and less than practical for our needs, and I used the method that ic-racer described. I would use 8 standard 35mm reels in a 13" (IIRC) tank.
Originally Posted by ic-racer
This actually worked out pretty well, as the cameras were operated intermittently by the tellers, taking a few frames at a time; unless the alarm was tripped, which ran the camera until the alarm was reset or (more usually) it ran out of film. In either case, working backward from the end of the exposed part of the roll got me the picture of the actor in question. Even with a robbery, I rarely had to go back past the last 20-25 ft. I would get on the first 8 reels.