At 15:03 1/2/02, Bill Pearce wrote:
This is the first I have heard about the lack of sharpness in a 36, but the
discussion about film flatness in 120 appears regularly on photo.net and
others. The theory is that film takes a "set" when rolled up, and won't
fully flaten out while being exposed. the MF discussion centers mainly
around Hasselblad, with the reverse curl wind in the backs. The argument
goes, when film is left in the back for a time, the first frame will have a
unsharp strip in it, that corresponds to the roller. I would suppose that
this would be a potential problem with a 36 roll in the last frames, wound
smaller and tighter.
The other theory (see also Bob Monaghan's Medium Format site), one that has
fixed many medium format cameras, is stiffening the pressure plate
springs. They are weak on some makes/models and further weaken with
use/age. Holding 120 and 220 film against the rails and keeping it flat in
a medium format camera is also a greater technical challenge.
The spindle in a 35mm film cannister is the same diameter whether it's 12,
20, 24 or 36 exposure. A 36 exposure strip doesn't make the inside of the
cannister that crowded. IMO it's Urban Legend. I've never seen anything
in hundreds of rolls of film that could be attributed to a difference in
how many exposures are on the film, or whether it was the 1st frame or 36th
frame.
Personally, I don't like to leave film in the camera for other, more mundane
reasons, so I will spend my time counting angels on pinheads.
I don't like to do this either; my mundane reason is keeping latent image
degradation to an absolute minimum. I use 36 exp. rolls, and if there's
film left will either process a short roll or find something to shoot with
the rest of it, typically an experiment to try something different. My
"burn rate" is usually high and the 36 exp. rolls reduce the amount of film
reloading. Since I shoot about 95%+ transparency, film cost and processing
cost is the same for a short roll as it is for a fully exposed one. Might
as well use any additional ones left for something. Transparency film is
not that expensive and the processing is cheap.
-- John
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