Strangely fuzzy Leica 90/2.8

[Jesper]

I have a peculiar problem with a Leica 90/2.8. All pictures turn out severely out of focus. The lens is an old one from -65 but is fine mechanically and glass looks fine. Whatever camera I use it on (M2, M3 and M4) gives the same result and changing to an older 90/4 (or any other lens I have) gives me sharp negatives. The problem is clearly connected to the 90/2.8 lens. Focusing with the viewfinder and checking the distance scale on the lens (both long distances and close up) gives me correct readings. Everything seems fine except for the negatives turning out fuzzy. There is really nothing sharp at any distance so it is not a question about incorrect focusing. Everything is just out of focus at a level that is clearly visible on the negative when viewed by the naked eye.



Has anyone had a similar experience and is there any use in trying to get it fixed?

Should I get another one or is there a risk that I get a similar lens (I guess that question is really answered by the first half of the first one)?

 

[Jim Jones]

Once I had trouble with a 90/2.8 beginning to produce slightly unsharp images after years of perfect performance. It turned out to a bit of dirt between the lens head and the focusing mount. This probably happened when the head was removed for lens cleaning. Your problem sounds worse. Perhaps a previous owner improperly reassembled the lens. Perhaps an element has become loose. Usually amateur attempts at repairs leave incriminating marks, always a danger signal.

 

[RalphLambrecht]

Once I had trouble with a 90/2.8 beginning to produce slightly unsharp images after years of perfect performance. It turned out to a bit of dirt between the lens head and the focusing mount. This probably happened when the head was removed for lens cleaning. Your problem sounds worse. Perhaps a previous owner improperly reassembled the lens. Perhaps an element has become loose. Usually amateur attempts at repairs leave incriminating marks, always a danger signal.

definitely a case for a professional repair; don't risk ruining the lens.

 

[Jesper]

I forgot to mention that I don't attempt repairs myself and that it has been to repairs once but the problem remains. Maybe I should try another repairman. Another alternative is to get another one. They are not that expensive but I wanted to know the odds of getting a new one with the same problem.

 

[voceumana]

Can you use the lens to focus a subject on a piece of paper without using the camera--i.e., can the lens focus at all? Does it work as a magnifier?

This will tell you if the lens has internal element spacing problems or if it is just an overall alignment of the lens--the mounting mechanism might be moved in or out of its proper position.

 

[Jesper]

Good question. It works fine as a magnifier.

 

[E. von Hoegh]

It sounds like the focussing mount might be improperly assembled.
Have it serviced by someone who knows these lenses, it could still have a mispositioned element, or other troubles.

 

[mgb74]

Unless you bought it new, you never know what has been done to it (and by whom) in the past.

 

[voceumana]

If it is a screw mount lens with an M adapter, then remove the adapter and reseat it or try a different adapter; otherwise off to the repair shop.

 

[Jesper]

Unless you bought it new, you never know what has been done to it (and by whom) in the past.

With a lens made in -65 you're not likely to be the first owner so I have to live with the uncertainty of what happened to it in its previous life. I will put it on the shelf with the other lenses that can't be used but might be fixed and get me another one. I don't think I will send it off to repairs once more.
It is by the way M mount, otherwise I would have suspected the adapter.
Thanks for the input.

 

[BrianVS]

Have you determined if the lens is front-focusing or back-focusing? Set it up to photograph a tape measure, something that can determine if if focus point of the actual image is off. If nothing is in focus, the elements in the barrel are misaligned. If the image is in back of the point that you focused on, the barrel needs to be moved out farther in the barrel. If the image is too close- the barrel needs to screw farther into the focus mount. Leica did not use shims, there is a chance that someone put a good-looking optic into a different focus mount.

I have some lenses that were assembled in 1950 that never worked. They are much better now.

 

[Jesper]

I have tried to see if it focuses at a different distance but no luck with that. It is fuzzy all the way. To be honest I've given up on it and it now rests at the back of my lens cupboard with a label reading "fuzzy" so that I will not use it by mistake. I got myself another one and that one works as it should.

 

[BrianVS]

If you can post an photo taken with the lens- would be interested in seeing it. I've seen a Summicron 5cm F2 Rigid that had TWO elements installed backwards. I've seen lenses with the wrong elements put in, just to make it look good to sell.

 

[Jesper]

Sorry, no digital pictures, just paper prints.

 

[BrianVS]

If you have any kind of digital camera, take a picture of the lens with a light shining through the back of it. This would help diagnose if it is haze, fungus, etching- etc. If none of those, either an element is loose or the barrel is not mounted correctly in the focus mount. Might be a simple fix, maybe not.