Mamiya Sekor 127mm f4.7 helicoid damage (?)

[melberi]

Hello,

I'm a proud new owner of a slightly troubled Mamiya Press lens. The problem at the outset is inability to reach infinity on the focusing scale. It stops just slightly before. I have opened the lens and discovered a sizable nick near the end of the helicoid which prevents the thread on the front element from reaching the end of the helicoid.

I wonder how this kind of damage could have even come about, if it is damage. Or maybe it is a kind of stopper, i.e. intended feature. Somebody must have seen this lens before and can tell how it is.

I could thread the front element to the helicoid from a slightly different starting point and reach infinity on the scale, but then on the minimum focus distance the front element loses its coupling to the mechanism.

Added complication is that I don't have a 'proper' camera for this lens to be able to see if the lens currently can reach infinity focus or not. The lens is destined for adapting to Instax Wide 300 camera.

 

[Mamiya_Repair]

Hi, it appears that the small post above the helicoid is preventing the lens from reaching infinity. This post is some sort of artifact, not part of the original lens design and was added at some point for an unknown function. The top of the helicoid should be flat. Perhaps it is attached from the outside of the lens barrel and could be removed?

 

[melberi]

Hi and thank you Bill for the answer! I will work to remove it then. The picture may be unclear, there is actually no excess material. The edge at the top of the helicoid has been either punched or drilled causing the blockage of the thread.

 

[Daire Quinlan]

Ha, I was with Bill, I read it originally as a metal post that looked as though it been screwed into the side of the barrel. It's like one of those optical illusions that can look like a stack of cubes or a single small cube in the corner of a room.