Mamiya 645pro focus issues?

tnewell · May 1, 2022

Hey everyone,
i've been using my mamiya 645pro for a while now, but for the last few months i've noticed the focusing is slightly off - frustratingly by only a hair or so. I've always found it a bit troublesome to focus on that camera personally, but havn't really had constant focus issues with it until recently.. so hard to see correctly through it...for reference the lenses i use are 80mm and 150mm..same sort of issue. Any ideas??

abruzzi · May 1, 2022

the first thing most will reccomend is to ensure that there really is a focus issue with your equipment and not a mistake or user error:

- set the camera on a tripod and lock dow in horizontal position.
- mount a ruler, yardstick, or simlar at a 45 degree angle to horizontal, and relatively close to the minimum focusing distance of the lens.
- focus the lens to a specific number or mark on the ruler
- shoot the photo with the aperture as wide as possible (preferably wide open)

make sure you remember where you focused so when you develop the film you can compare where you focused to where the photo is focused. If there is a discrepancy, you may have a hardware issue, if not, it may be a user issue.

MattKing · May 1, 2022

abruzzi's suggestions are good.
There is a possibility that your camera is showing signs that the mirror bumpers are worn. Those bumpers were designed to be a target of regular service/replacement in heavily used cameras, but as there are no longer parts available from the manufacturer, others have stepped forward with replacement options.
@Mamiya_Repair may chime in here with a suggestion.

McDiesel · May 1, 2022

@tnewell this video is exactly what you need.

Mamiya_Repair · May 1, 2022

MattKing said:
abruzzi's suggestions are good.
There is a possibility that your camera is showing signs that the mirror bumpers are worn. Those bumpers were designed to be a target of regular service/replacement in heavily used cameras, but as there are no longer parts available from the manufacturer, others have stepped forward with replacement options.
@Mamiya_Repair may chime in here with a suggestion.

Yes, I would be almost certain that the issue is a broken mirror stop. If you focus on a distant object and can't quite get the lens to focus, this is your problem. The mirror stop is a plastic material and will break after all these decades. Every Mamiya 645 Super or Pro that you see for sale has either a broken mirror stop or one that is about to break. Without the mirror being at the correct 45 degree angle, focus will be off. The big issue of using a Mamiya 645 Super or Pro with a broken mirror stop is that the broken piece and/or the spring can eventually get into the shutter curtains and cause mischief.

tnewell · May 11, 2022

Mamiya_Repair said:
Yes, I would be almost certain that the issue is a broken mirror stop. If you focus on a distant object and can't quite get the lens to focus, this is your problem. The mirror stop is a plastic material and will break after all these decades. Every Mamiya 645 Super or Pro that you see for sale has either a broken mirror stop or one that is about to break. Without the mirror being at the correct 45 degree angle, focus will be off. The big issue of using a Mamiya 645 Super or Pro with a broken mirror stop is that the broken piece and/or the spring can eventually get into the shutter curtains and cause mischief.

Funnily enough, prior to this my shutter seemed to jam when i was shooting and the whole camera locked up...i managed to jiggle the mirror carefully so that it would return to its original poisition...but it maybe has something to do with that. thanks for the reply.

eradman · Feb 6, 2023

There is a "Mamiya 645 Pro Mirror replacement" model on Thingiverse

Mamiya 645 Pro Mirror stop replacement by vdani666

This is a replacement part for the Mamiya 645 Pro(and I think it works with other models to in the lineup) mirror stop. This part is broken in the cameras, or will broke. I can not find any free version of this, so I made one. I hope I could help. I updated the design after printing the first...

www.thingiverse.com

IMoL · Feb 7, 2023

eradman said:
There is a "Mamiya 645 Pro Mirror replacement" model on Thingiverse

Mamiya 645 Pro Mirror stop replacement by vdani666

This is a replacement part for the Mamiya 645 Pro(and I think it works with other models to in the lineup) mirror stop. This part is broken in the cameras, or will broke. I can not find any free version of this, so I made one. I hope I could help. I updated the design after printing the first...

www.thingiverse.com

I had a couple of these made up by Shapeways from this design and they worked really well. Installation can be a bit of a PITA getting the spring back in the right place, but the actual piece is good. I had them made up in PA12 Nylon, and it's probably stronger than the original plastic piece.

Mamiya 645pro focus issues?

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