Originally posted by BandeauRouge I own a mamiya 645 1000s. Been considering a pentax 645 but have following questions
How does the aperture fire on the pentax lenses? I can get an adapter ring to fit them to a mamiya, but not finding much on how the aperture will function.
Ive been thinking on a manual shutter system, but I do need lenses..
I don't know if I'm reading your question incorrectly, but I would be astonished if you could find an adapter to mount Pentax 645 lenses onto a Mamiya 645 body. As far as I know, there is no stand-alone adapter commercially available, and I haven't found any boutique camera modifiers who offer them on small volume either. Everyone who has mounted Pentax 645 lenses onto Mamiya 645 camera bodies has adapted/modified the lens itself by stripping off the bayonet and attaching a modified Mamiya bayonet.
If there is an adapter available, I would certainly love to know!
I have adapted two P645 lenses to Mamiya 645. One was the A 35mm. You need to maintain the spring tension on the aperture lever, and then simply use the aperture ring on the lens to adjust as needed. Completely manual operation.
The other lens I have adapted is the 645 DA 28-45mm. Like the A 35mm, I had to strip the bayonet off it, but my adapting plate/spacer for this one needed an aperture ring to engage with the aperture pin on the back of the lens - much more complicated, but still completely manual operation.
I would like to sit down one day and try to 3D model an actual adapter to see if it is possible, but with less than 8mm to work with between the two flange faces, there's not a lot of space. I kinda feel that if it were possible the big boys ( Fotodiox, Kipon ) would have tried by now.
I do think it's a worthwhile pursuit, depending on what your level of expectation is for image quality. The Pentax range of 645 35mm lenses are better than the Mamiya 35, and Mamiya doesn't really have any equivalent of the 45-85mm that I'm aware of. There is also the 33-55mm that has no equivalent in Mamiya 645 mount for something even wider.
Some pictures that I dug up of my adapting attempts. A couple of pics of the 28-45mm adapted can be found
here, due to Pentax Forums not letting me upload the same photos twice.