Lens not locking

[andydg]

I just got a new Zeiss 28mm lens and noticed that the locking tab on my M6 will not seat all the way when I twist the lens on. On an M4 I am evaluating it does lock, as does the 50mm Planar I have on the M6. Weird. Has anyone any ideas? It would be a bummer if the lens were to come off when in use.

 

[jmcd]

I have a newer Elmar that is too tight to mount on my M5, but it mounts fine on the M6. I too wonder about a possible solution.

 

[andydg]

If it weren't brand new, I would attempt to adjust the lens mount. There appears to be a slight amount of play by the looks of the screw holes. All of them have a 1/2 mm gap to the left of the screw, probably just enough to let the lens lock in place. I've emailed Zeiss about it and also the place where I purchased the lens and asked for an exchange.

Image is of the lens.

 

[Juan Valdenebro]

I asked the same for my 90 Summicron on my Bessas T: it locks on my Bessa R4M, and all my other lenses lock on my T's... Doesn't make sense... Yet I think there must be a solution...

Cheers,

Juan

 

[jmcd]

I have the same pattern on my 35/2, with respect to the gap to the left of the screw (my 35/2 mounts fine.)

Best wishes on the exchange. That sounds like a good plan.

 

[Juan Valdenebro]

I forgot to mention this happens between some lenses and cameras of different brands, as confirmed by Roger Hicks, who has several similar cases with his equipment, and it's not a sample problem, but a result of minimal pins' tolerances and variations which are not easy to fix without creating new problems... I sometimes look at my summicron back and its pin hole, and I wonder if I could do something...

Cheers,

Juan

 

[Nikon Bob]

I had a similar problem with a screw to M adapter. The lens with adapter would lock on one M and not the other. IIRC the problem was solved by honing back a lug on the adapter to allow it to rotate just enough on the non locking M to actually lock. It took very little to do that. I would NOT suggest doing that on a new lens but I would just exchange it for one that worked on both your Ms.

Bob