'Slight Balsam separation' on a Folder lens

[SCOTFORTHLAD]

As a I am no lens aficianado,could someone explain the above description which I recently saw applied to the lens on a 120 Folder.

Thanks,
Brian.

[Solinar]

Brian, it sounds like the rear group on someone's Xenar or Tessar are starting to separate. Canadian balsam is the optically clear cement holding the two rear elements together as a group.

If it is slight, which would be only towards one edge, then the lens may be ok when stopped down.

[SCOTFORTHLAD]

Thanks for the info' Andrew---a little more insight for me .
From memory it was a Tessar on an Ikonta.

Cheers,
Brian.

[FallisPhoto]

Originally Posted by SCOTFORTHLAD

Thanks for the info' Andrew---a little more insight for me .
From memory it was a Tessar on an Ikonta.

Cheers,
Brian.

I have heard of people melting the balsam cement and sticking them back together. Always sounded like a very haphazard and risky operation to me though.

[fidget]

I once had an Isolette with a f4.5 Solinar lens. It seemed to have some haze on the centre element (at least I think it was the centre group). I took it out and tried to clean it, the haze was only around the outer part of the lens. The cleaning attempts were of no use, it stayed hazy.
After some further cleaning using increasingly noxious chemicals i realized that the haze I could see was actually between two elements and that it was now slightly worse that when I started "cleaning" it. I think that the chems I used were attacking the cement and making the haze worse. That was one that I couldn't fix.

[FallisPhoto]

Originally Posted by fidget

I once had an Isolette with a f4.5 Solinar lens. It seemed to have some haze on the centre element (at least I think it was the centre group). I took it out and tried to clean it, the haze was only around the outer part of the lens. The cleaning attempts were of no use, it stayed hazy.
After some further cleaning using increasingly noxious chemicals i realized that the haze I could see was actually between two elements and that it was now slightly worse that when I started "cleaning" it. I think that the chems I used were attacking the cement and making the haze worse. That was one that I couldn't fix.

I've got an old Skopar that has bubbles (really tiny ones) between a couple of elements. Any photo I take with that lens gets one little pinpoint black spot that has to be bleached out or removed digitally. Before realizing what and where they were, I spent a lot of time trying to clean those "spots" off of the glass though. I wonder what causes that, because I've seen several older Zeiss lenses that have those bubbles (impurities in the balsam maybe?).