In a past thread on the net about the Pentax 6X7 and P67 vibrations, I was shot down for pointing out that a mirror cushion was utilized... "There is no foam on a 67 for that to be the problem". Well, I possess the latest Service bulletin published and part# B94-02 is still on the list and it is the "Stopper Cushion" and no notation that it is limited to a specific model. Interestingly, I recall a few others in another thread also supported the idea that the cushions are not normally installed. I wonder if that is why they are getting poor low speed results. The cushion has a very specific thickness and density. I found out the hard way when I was replacing my gooey originals. The original set looked roughly look to be about 5mm, but that was too tall or too dense and so they jammed the mirror action. It worked fine when a 3mm set was installed.
I looked over the diagram again and I think I finally figured out where the single solution confusion comes from. Only one cushion is needed because on the left side or shutter dial side that the lone cushion is installed to damp the unsupported side. My camera had two sides and they were different. When I first got the camera it looked like one was very deteriorated on the right side and the other looked fuller and taller. I've since installed two thinner cushions and I wonder if that is why my slow speed pictures come out very good?
Update: Second 6X7 body acquired and I installed the second after getting less than satisfactory result at low speeds. The second foam is a thin 2mm dense foam and it seems to work find, but I'll only know when I process the film.
Update: So the best combination is the right side is thin, only 1.5mm about. The other side is best with around 3-4mm thick soft open cell mirror foam. I reviewed a few shot and they seem very good at low speeds.
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