Apo Lanthar 90/3.5 (LTM) with haze

[Sonnar2]

Has anyone tried to unglue cemented elements of Voigtlander LTM lenses?
I have haze in the cemented surface of the last, double element of a Voigtländer 90/3.5 (LTM) which I got recently. Obviously I wasn't testing carefully after buying, but now I noticed substancial contrast loss with backlite use.

Would heat help to unglue it? - I still have some Canada balsam from my last repair (Olympus 42/1.2)

Cheers, Frank

 

[Vobluda]

You will need to make a special tool to get into that lens.
Not sure that the lens is worth repairing, both in terms of value of the lens and picture quality as the lens is nothing special.

 

[Sonnar2]

I've got them out quickly (lens spanner wrench); now I'm asking about the glue Cosina uses.

 

[x-ray]

I've read on the large format forum that some people soak the groupings on some lenses in a solvent like xylene or acetone. I don't know how it would affect coatings if it's coated.

 

[sevo]

I've got them out quickly (lens spanner wrench); now I'm asking about the glue Cosina uses.

Certainly not balsam - that went out of use forty to seventy years ago. As the lens is fairly recent, probably some UV curing cement. You might want to try http://www.edmundoptics.com/lab-production/adhesives/milsolve-decementing-agent/3291/

 

[joeswe]

I hate to bring bad news, but it is doubtful whether his can be rectified by a simple cleaning. It is likely that the lens element(s) affected by haze has/have to be replaced. This can obviously only done by Cosina in Japan.

Background: Two years ago I chatted with a Japanese s/h camera dealer specializing in RF gear about this lens and he kind of talked me out of buying one, saying that he had sold three copies of that lens of which two had been returned to him by the customers after they had developed haze. They had to be sent to Cosina for repair. He showed me the repair reports stating that a lens element had been replaced. Kind of reminded him of the issues with the Canon 100/3.5 LTM.

Still, maybe you are lucky and a cleaning job will do. Good luck!

 

[Pioneer]

Interesting thread.

I have two of these lenses, one in LTM and one in K-Mount, and I have always gotten very good results with them. I have just checked both of mine with a strong light and, aside from a few dust particles, I see no haze.

I guess I'll have to try them with strong backlighting. So far I am more than satisfied with these lenses so I hope this turns out to be an unusual problem.

 

[CameraQuest]

I hate to bring bad news, but it is doubtful whether his can be rectified by a simple cleaning. It is likely that the lens element(s) affected by haze has/have to be replaced. This can obviously only done by Cosina in Japan.

Background: Two years ago I chatted with a Japanese s/h camera dealer specializing in RF gear about this lens and he kind of talked me out of buying one, saying that he had sold three copies of that lens of which two had been returned to him by the customers after they had developed haze. They had to be sent to Cosina for repair. He showed me the repair reports stating that a lens element had been replaced. Kind of reminded him of the issues with the Canon 100/3.5 LTM.

Still, maybe you are lucky and a cleaning job will do. Good luck!

That is not my experience.
I've sold hundreds of the 90/3.5 LTM lenses (now discontinued).
I don't recall any of them being returned or repaired for haze problems.

It was a fine performer. Find Erwin Puts test and praise of it. Despite the performance it was discontinued for to slow sales thanks to F/3.5. You will have a difficult time finding a better 90mm performer in LTM and almost as difficult in M lenses without paying for the much more expensive Leica lenses.

Stephen

 

[joeswe]

That is not my experience.
I've sold hundreds of the 90/3.5 LTM lenses (now discontinued).
I don't recall any of them being returned or repaired for haze problems.

Stephen

I think this is kind of reassuring for anyone who is interested in buying the lens. I had already asked in a thread here on RFF some time ago if any fellow RFFers had experienced this haze problem and hadn't received any feedback at the time. Now reading this thread and your comment, I think it's fair to conclude that there may be problems with (very few) individual samples of the lens, but not with the lens in general. Maybe specific storage conditions play a role. Humidity comes to my mind.

 

[Pioneer]

This particular lens has not been one Cosina's sales successes. To a large extent this seems to be because of the slower maximum aperture.

But my personal experience with this lens has revealed it to be an exceptional performer. For starters, the lens can very successfully be used wide open with little or no negative consequences. Second, it produces an amazingly even performance across the frame where border resolution is very similar to the center performance from f3.5 all the way to f22. I am told it begins to show diffraction at f/11 but this does not seem to be a visible issue with my photographs. It does reveal a small amount of vignetting around the outside when it is wide open but by f5.6 it is basically gone. This is a great feature for portrait photography, but even with other types of photography it seems to work quite well and is not intrusive at all. Finally, I find the out of focus blur from this lens to be very smooth, both in transition as well as further out into the frame.

The Apo designation means it produces some excellent color photographs and, though I don't shoot a lot of color, I often make an exception with this lens. I love the way this lens renders color all the way through the frame, even with out of focus sections, and I am frequently grabbing an occasional roll of Kodak Portra in an almost subconscious salute to this lenses strengths. I have never mounted it on my digital Leica cameras so I really cannot provide any feedback on its digital performance. Perhaps someone else can attest to how it works with an M9 or other digital Leica.

I enjoy using my Elmar 90/4 but for my money, this lens easily outperforms that older lens. I use this lens for landscape, portraits and for certain sports photography where the 90mm focal length is very useful. I can almost always shoot at f3.5 and 1/60 seconds on ISO400 film inside a well lit gymnasium. Since this lens has such wonderful resolution and color performance across the frame when wide open, I have found no reason to stop it down.

It certainly is not a Summicron 90, but it is a magnificent performer none the less. If you own one of these lenses and have been neglecting it recently I challenge you to take it out for a stroll...or two...or three. You may be surprised at what you end up with.