M3: Lenses are very hard to mount

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I recently got an M3 which was used last time 10 years ago. However, it was serviced around 15 years ago.

The problem of the camera is that it is very hard to mount a lens (Elmar 50, Summaron 35 or CV Skopar 35).

 

It feels like two metal pieces press against each other when mounting or unmounting a lens.

There is high pressure between lens and bajonet and a high resistance during mounting.

 

Does anyone know or had such a problem with an Leica M model?

 

I plan to send the camera to a service but hope to get here some information before.

Or in best case I can perhaps solve the problem by myself with the help of suggestions.

 

Best Wishes

 

[TomB_tx]

I have several M cameras (various models) and the resistance to mounting lenses varies quite a bit over the samples. One of my M3's (a 1955 DS) has had the same issue, and I've noticed some lenses mount harder on it than others, so tolerances on both lens and body are involved. I also notice some lenses (like my DR Summicron) are even hard to insert into the mount fully in order to turn in place. I suspect it may be that the mount, the circular leaf spring that pulls the lens tight, and the body opening behind the mount may not be aligned perfectly concentric, as a lens tends to "catch" a bit as it's inserted part way. I've been meaning to loosen the mount screws and see if I can align it all better, but have to first remove the wax seal that was put in place over the top screwduring the last CLA.

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[earleygallery]

Try a very very light application of grease on the face of the mount.

[TomB_tx]

OK, I decided to investigate the mount alignment of my DS M3 that has been very hard to mount lenses. I first went to loosen the mounting screws, and found they were not all the same tightness. I had to dig out the wax seal over the top screw (no L stamp, so not original) to first set the all loose a turn or so. Then trial fitting my DR Summicron found it inserted easily, without the “catch” partway inserted that has been part of the problem. I then gradually tightened all 5 screws 1/4 turn each while re-inserting the lens after each step to make sure all remained concentric. Finally snugged up all screws evenly in criss-cross fashion.

Lenses now mount much easier and smoother.

A slight film of lube on the mount face didn’t seem to make a difference, but a bit on the back of the lens bayonet “ears” where they rub on the tension spring of the body mount also improved the action.

Edited August 8, 2018 by TomB_tx

[250swb]

Good to hear of your DIY job Tom. I've never come across this problem with the body mount, but have many times had lenses where the flange screws were lose so the lens flange isn't properly centered (which causes the focus to become stiff and notchy). But it makes sense, I suppose the rotational torque involved in mounting and dismounting a lens adds an equal strain on the screws holding the mount to the body, it may only take one to be a bit loser and the rest then follow.

Edited August 9, 2018 by 250swb

[Beresford]

I'm really glad to read about this problem. I have an M3 DS and I have noticed that the lens mounting is tighter than on my other Ms. 

 

My question is, Should I use a tiny touch of Vaseline or some other lube? I know! 'tiny' is important. And TomB_tx's advice to put it on the back of the bayonet "ears" sounds excellent. Would it be enough to do it on one lens and then allow that to transfer the lube?

 

Sorry to sound dim - but I am not the most practical person, and would like to get it right.

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Thank you all very much for your experiences and suggestions!

I am not at home this weekend but I wil try your suggestions when I am back on sunday.

I will give Feedback then.

 

Have all a nice weekend!

[250swb]

I'm really glad to read about this problem. I have an M3 DS and I have noticed that the lens mounting is tighter than on my other Ms. 

 

My question is, Should I use a tiny touch of Vaseline or some other lube? I know! 'tiny' is important. And TomB_tx's advice to put it on the back of the bayonet "ears" sounds excellent. Would it be enough to do it on one lens and then allow that to transfer the lube?

 

Sorry to sound dim - but I am not the most practical person, and would like to get it right.

 

I think it is a mechanical problem, not a lubrication problem, very different things. Leica have never ever lubricated the lens mounts or lens flanges, they were never designed to be lubricated, it is a bad idea. Lubrication on an outer surface not only automatically means the possibility of cross contamination, so more greasy marks all around the camera and lens surfaces, but also attracting dust and dirt. You just end up with a film of gunk everywhere, on your fingers, rear lens caps, smearing the viewfinder, so don't do it.

Edited August 10, 2018 by 250swb

[Lukas F.]

From what I understand vaseline is a lubricant too (but no grease) and Leica seems to recommend applying a *thin* (I can't stress that word enough...) coat of vaseline to the lens mount of the lens in situations like this (if the lubrication applied during manufacturing is gone). However, I get the feeling that in this case it's really rather a mechanical problem, like 250swb said.