Mamiya Press 50mm f/6.3: Dented Rear Rim and Stuck Seikosha-S Shutter
Originally posted on Instagram. Notes from the repair bench, kept here as a searchable archive. View the original on Instagram
This 50mm f/6.3 Mamiya Press Lens arrived in the shop with a couple of issues: the rear element group had a very severe ding on the edge. And the shutter did not release.
The third photo shows the extent of the damage to the rear element group rim when the lens arrived and the fourth photo shows it much happier after some attention was paid to the dent. Fortunately, there was not a previous attempt to straighten this out so it turned out well.
The next two photos show the shutter with the front element and then the shutter speed control ring removed. As you can see, this lens has a standard Seikosha-S shutter installed. Generally, when you interface with these shutters on the Press series, you are directly working the shutter controls but on the 50mm, due to it’s design, there are external controls for cocking, release and “X/M”.
After cleaning and checking operation, final step is to check focus and as seen in photo eight, the lens produces a very crisp target wide open.
A little info on the 50mm Mamiya Press lens: It is a Biogon formula, eight elements in five groups. This particular example is from May of 1968. I often find these used on custom made wide angle cameras and the lens is a very good performer.
