Canon 50/1.2 getting wobbly ?

[Corvi]

Hey Lads,

I've got a little problem here. I own a very very nice Canon 50/1.2 RF lens, but, the front part of it including aperture ring and stuff gets more and more wobbly at the time. I can already move the whole front element around when i take the aperture ring and move it around. The whole lens is shaking around and making noises ..

Now i already opened the lens from the rear, removing focus ring and rear section, but i cant figure out why its so wobbly. What i found out is that both parts, front and rear, by themselves are not wobbly at all. Only the two together kinda don't fit and move around. I already tightened all screws, tightened the rear ring with a spanner wrench, but its still not fits perfectly. I can remember that i wasnt doing this some time ago, so it just got lose in the past 2-3 month now. Its driving me crazy. Anyone here knows that problem and can maybe help me out a little ?

 

[John Shriver]

Maybe you (or a prior owner) lost the brass spacer ring (selected shim) that goes between the optical block (aperture and two lens blocks) and the focusing mount. Without that shim, the optical block may not seat properly in the focusing mount. Without the shim, it also won't focus accurately...

If there isn't one there, there should be.

 

[peterm1]

From your description you probably already know this but it may be that this article provides some leads althought its main focus is on cleaning of the lens.

http://portretteur.nl/index.php?opt...12-rangefinder-lens&catid=37:lenses&Itemid=58

I have one which is tight enough. My problem is that my lens needs recollimating as it is not focussing well -it was previously, but then took a knock that seems to have upset it.

 

[Corvi]

Yeh i know that link already, but it didn't help me. And, the brass ring is there and the lens focuses spot on, so thats not the problem. It just feels like its falling apart.

While it disassembled it i noticed that in the focusing mount without the glass there are two brass helicoids which are most likely the focusing mechanism. Now those two parts are moving against each other. The outer one is attached to the focusing ring with several screws, the inner one is the one that pushes the rangefinder wheel while focusing. And those two seem to have some pretty big tolerance, because the inner one is apparently a smaller than it should be, therefor wobbling around the whole lens when assembled. It really is weird. I got that lens for years now and it never had anything, and now suddenly it starts to come apart :/