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04-28-2023, 09:12 AM   #1
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Lenses 645

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..

04-28-2023, 09:38 AM   #2
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Depends on film or digital. Lenses strinctly for the 645D CCD and 645Z CMOS APS digital cameras control the aperture on the D-series lenses like Pentax-D FA 645 55mm f/2.8 AL[IF] SDM AW Lens electronically - there is no manual aperture ring.
The FA lenses can be used on film or digital and have a manual aperture dial and lever that the camera can move to stop down the lens during the shot, and keep it wide open during focusing/framing.
None of them are leaf shutter lenses, with the exception of the 75mm f/2.8 LS lens which is an older lens (and there may be one I am forgetting)..
04-28-2023, 12:44 PM   #3
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QuoteOriginally posted by BandeauRouge Quote
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..
Since Pentax is a longer mount that should work with A and FA lenses. Those have aperture rings. What’s the exact adapter?
04-28-2023, 01:19 PM   #4
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QuoteOriginally posted by BandeauRouge Quote
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'm assuming you're considering the 645 film camera. They Pentax-A lenses have an aperture ring and aperture stops down with a lever on the front right side (or left side if you're looking into the mount). I would expect any adapter to not provide aperture linkage, so meter is manual stopped down. If you can mount the mamiya lens, it should be usable. Also, 645 Pentax-A lenses are often cheap. The 200mm is usually in the $50-100 range, the 45-85 and 80-160 are usually around $100. Unfortunate, the 75/2.8 isn't ever that cheap...usually $300 range. You can sometimes find a 645 with lenses for a good price. I got mine with a 55, 75 and 80-160 for about $600.



04-28-2023, 04:15 PM   #5
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bh photo video sells adapter for it...

crap its actually pentax 67 lenses to mamiya 645..

but alot of stuff to put pentax 67 and 645 lenses onto a k mount
04-28-2023, 05:30 PM - 1 Like   #6
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QuoteOriginally posted by BandeauRouge Quote
bh photo video sells adapter for it...

crap its actually pentax 67 lenses to mamiya 645..

but alot of stuff to put pentax 67 and 645 lenses onto a k mount
There are people who have made adapters for this purpose. The difference in mount distance is not very much.

Pentax 645 on Mamiya 645?? - FM Forums

Mamiya 645 to Pentax 645 Lens Adapter? - Medium Format - Photo.net

Some of these allude to ways to make an adapter.
04-29-2023, 03:31 PM   #7
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Not the answer you are looking for maybe,
I'm using my old Mamiya 645 lenses adapted to the Fuji GFX series cameras,
Works pretty well,
I found a Kipon adaptor which has tilt and shift ability,
Fun to play around with.

05-01-2023, 06:56 PM - 2 Likes   #8
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QuoteOriginally posted by BandeauRouge Quote
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.
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