Color Heliar 75mm f2.5 haze cleaning?

[jc031699]

Hi, I was wondering if anyone here has experience cleaning haze from this lens?

There is one mention in Pentax Forums recementing the rear element due to “haze” but it doesn’t sound right.

Similar to what I recently determined (I think…) regarding the Bessa R rangefinder adjustment, these one-off single instance internet mentions have a way of becoming dogma / accepted fact perhaps without sufficient evidence.

Thanks for any insight which you may have, hive mind.

The head bartender would likely have the inside scoop. Any of the vets here know how to conjure him? 😁

 

[Coldkennels]

If you're talking about the original LTM one... this is a known issue.

As per Skyllaney:

In certain optical formulas, haze can get trapped between two elements on a doublet or triplet stack. In these situations, it’s very difficult to separate the two elements, and precisely rebond them after cleaning. We have mostly seen this on Voigtlander LTM and VM lenses, as well as older Minolta M-Rokkor lenses. At the moment, we don’t have the facility to do this type of separation and rebonding.

Basically, if you've got haze in an early Voigtlander lens, there's a good chance you're stuck with it.

 

[jc031699]

Great info, thank you-

 

[WoodallP]

Hi, I realise that there is some context in the original question and I promise I am not trolling but when you say “early Voigtlander” I suppose it’s early Cosina Voigtlander, but I’m not sure when that was. Are there particular date ranges to avoid?

 

[Retro-Grouch]

If you're talking about the original LTM one... this is a known issue.

As per Skyllaney:



Basically, if you've got haze in an early Voigtlander lens, there's a good chance you're stuck with it.

I received the same answer from Skyllaney about my CV 28/3.5 in Nikon S mount, made at the same time as the early LTM lenses. They're experts on this sort of thing, so I trust their assessment.

 

[Darthfeeble]

I had a Canon 100mm ltm lens that was hazy, took beautiful portraits. I got filled with courage one day an took it apart and cleaned all the elements with rubbing alky with great results but I ruined the dreamy portrait lens in that it was very sharp after. They're pretty simple from back then, just don't mess with the focus mechanism and keep all the elements in proper order and orientation.

 

[Sonnar Brian]

The AF-D Nikkor 20mm F3.5 has the same problem. A person on another forum posted that they heated the elements in cooking oil to separate, then re-assembled without using cement, worked well enough. I've used index matching oil used for immersion microscope lenses before. A future project for me.

 

[leolab]

i recently bought the skopar 28mm 3.5 and 21mm f4 in Nikon S Mount, they did have haze, i took a chance based on ‘throw it away’ price. I opened the lenses and cleaned the two surfaces facing the aperture blades and they are as good as new. I know that haze can also develop between cemented elements for some of the LTM voigts, which is near impossible to get rid of, but based on my experience that may not always be the issue. The 75mm is notorious for developing haze between cemented elements, but i think some of the skopars may not be so inclined.

 

[Coldkennels]

i recently bought the skopar 28mm 3.5 and 21mm f4 in Nikon S Mount, they did have haze, i took a chance based on ‘throw it away’ price. I opened the lenses and cleaned the two surfaces facing the aperture blades and they are as good as new. I know that haze can also develop between cemented elements for some of the LTM voigts, which is near impossible to get rid of, but based on my experience that may not always be the issue. The 75mm is notorious for developing haze between cemented elements, but i think some of the skopars may not be so inclined.

That's good to know. My LTM 21mm f/4 Skopar is getting a little hazy - I wouldn't mind getting that cleaned up a bit.

 

[jc031699]

I got a color heliar 75/2.5 at a great price. I can confirm that there was a bit of haze on the surfaces of the 2 rear groups/elements that cleaned off easily. However, the rear group next to the aperture, which is a doublet, has some very subtle cloudiness apparently in the cement between the two elements. This is not separation, seems to be some kind of degradation / loss of absolute clarity of the cement.

I can’t see where it affects image quality, as there is no notable glow or flare resulting from shooting highlights or with bright light sources near/in the field.

The good news is that these two elements have flat cylindrical edges that could be amenable to recementing and mechanical concentric alignment. Maybe some day. I’ve done this with success with a beater throwaway canon FD 24 2.8 with rear element separation previously, using Norland 61. I am guessing based on the era that this is cement (not balsam) that would require MEK to separate. There is no sleeve or collar around these.

Also, there is a super thin retaining ring for the front elements, and same for the rear elements. I did not need to remove any “optical unit” or separate the focus mount.