Author Topic: Fixing "front focus" of Mamiya M645 Super  (Read 204 times)

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cs1

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Fixing "front focus" of Mamiya M645 Super
« on: December 23, 2017, 08:36:05 PM »
ManuelL was so kind to lend me his Mamiya M645 Super. ManuelL said that he had had considerable problems with focusing properly when shooting with wide open apertures. I tested the camera and it seems like there's indeed a lot of front focus. After searching around for a bit I found that it's very likely that this may be due to a misaligned mirror stop which seems to be a week spot of the M645 Super. I'm currently struggling with myself how I should approach this. On other cameras I'd probably try to adjust the focusing screen. However, on the M645 Super, a misaligned mirror stop makes perfect sense and it seems easy enough to fix by fiddling with the mirror stop adjustment screw. Have any of you experiences with this kind of issue? Any advice on how to approach this? Every useful hint is highly appreciated.

PeterR

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Re: Fixing "front focus" of Mamiya M645 Super
« Reply #1 on: December 23, 2017, 09:59:59 PM »
It is a common problem with them. First thing to ascertain is if the mirror stop is broken which it often is. If so, then there's not much you can do unless you can get a replacement. I got one from Johnsons in the UK several years ago but no idea if they would still have them (or even if Johnsons still exist). They were the importers of Mamiya.

If the stop is all OK, then go ahead and adjust the screw.
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cs1

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Re: Fixing "front focus" of Mamiya M645 Super
« Reply #2 on: December 23, 2017, 10:05:15 PM »
The mirror stop looks ok. Nothing's broken as far as I can tell. It seems like I need to adjust the stop so that the mirror tilts up a tiny little bit. The mirror stop looks very plasticky though. I'm surprised that it's so flimsy compared to the rest of the camera. No wonder that it's a weak spot.

Thanks for the confirmation regarding the mirror stop adjustment, Peter.

PeterR

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Re: Fixing "front focus" of Mamiya M645 Super
« Reply #3 on: December 23, 2017, 10:12:00 PM »
There's also a spring that allows the mirror stop to give a bit when the mirror comes down. Too long ago for me to remember exactly how it looks and I can't find a picture but maybe worth checking if the stop can move and springs back to its normal position against the screw.
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cs1

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Re: Fixing "front focus" of Mamiya M645 Super
« Reply #4 on: December 23, 2017, 10:13:38 PM »
Yes, I saw the spring. Good advice, I'll have a closer look at it.

cs1

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Re: Fixing "front focus" of Mamiya M645 Super
« Reply #5 on: December 24, 2017, 09:44:29 AM »
Oh well, a thorough investigation with magnifiers yielded that (a) the stop is broken and (b) someone (not ManuelL) tried to fiddle with it already.

The only chance I see is to have a custom part manufactured. Maybe 3D printed but ideally something made from brass or some other sort of metal. It seems like the original part is almost impossible to find.

PeterR

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Re: Fixing "front focus" of Mamiya M645 Super
« Reply #6 on: December 24, 2017, 12:37:10 PM »
You're in the UK aren't you? Johnsons still exist and it would be worth given them a call to see if they can still supply the part.

I remember it wasn't easy to fit but did get it done.
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cs1

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Re: Fixing "front focus" of Mamiya M645 Super
« Reply #7 on: December 24, 2017, 04:28:48 PM »
I'm in Germany but postage from the UK to DE shouldn't be that much for such a small part. I'll try to contact them and find out how much the stop is.