I finally talked to Edwin Schouten this afternoon, the cameratech from ETKON here in Amsterdam. (Marc I have to give you his regards!)
He told me it is a well known problem and has to do with the fact that ORWO is firmer and also somewhat rougher physically than Kodak and Fuji stock. He said all the old LTR's have this problem, and it is because of a modified pressure plate in the newer magazines that those newer Aatons can handle it better. The newer ones have a smoother top which reduces friction by a large amount. See picture for the newer version in one of my magazines.
Aatons don't use a registration pin (like Arri's do), and the film keeps on moving a tiny tiny little bit when the transportation pin retracts, which is normal and the camera is adjusted to that. With the use of the stiffer and rougher ORWO stock and the older pressure plates this movement is less, which makes the transportation pin hitting the film instead of entering the perforation. Film skips a frame but the sprockets advance the film > you loose your loop.
In the ARRI's the registration pin immediately stops the film, so roughness doesn't matter. Bolexes, Krasnogorsk etc are probably much less precise and will handle anything you feed them.
Of course the camera can be adjusted to handle this stiffer and rougher stock perfectly well, but it has to be adjusted again if you want to use Kodak/Fuji.
By the way, I tested last weekend with 15 yr old UN 32 in my LTR, no problem at all. The 15 yr old Svema jammed, but it was visibly shrunken. I'll run it through a Bolex rex 5 just to see what happens one of the coming days.
Film doesn't shrink that easily if you store it well, I'm a filmscanner in my daytime job and have scanned thousands of archival prints in the last years. You probably see fading in your camerastock way before the shrinking will become a problem.
I'm curious if these pressure plate designs will solve the problem for the others?
Onno
