Mamiya 645 Super: Broken Mirror Stop Jamming Shutter Curtains
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
This is my annual reminder to owners of Mamiya 645 Super/Pro/Pro TL cameras to check their mirror stop. If your mirror stop has not been replaced in the last decade or so (if you just purchased the camera assume it is the original part) then your stop is either 1.) broken 2.) about to break. If you catch the issue before it crumbles apart you can possibly save money on deeper repairs (or worse, a not economically repairable camera). This is the most common issue that I see with the Mamiya 645 models (does not apply to the early 645 models without interchangeable backs)
This camera came into the shop with the shutter locked up. First inspection showed the mirror stop in the condition as shown in the second photo, with the bottom half gone and the spring nowhere to be seen.
On removing the covering on the back of the camera, my sight was as shown in photo three which is the bottom half of the mirror stop with the adjusting screws wedged into the shutter curtain. After removing this part I noticed that the shutter curtains were damaged. And the spring was gone (probably fell out of the camera at some point or went deeper into the mechanism and caused the shutter problem when some level of force was used to wind the shutter).
If you find that your mirror stop is broken, do not use the camera. You may prevent it from breaking and getting in places it should not be, like the shutter curtains or the shutter mechanism.
Easy way to check in the field is to focus on an infinity object (a light pole 1/2 mile away works well) and if you can not quite get the focus screen sharp or the split image to line up then your stop is broken. Make plans to have it taken care of.
I have done several posts on this in the past that show an intact stop and what the parts look like.
