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Cemented Groups & Balsam Seperation?

Started Jul 3, 2018 | Discussions
(unknown member) Veteran Member • Posts: 4,469
Cemented Groups & Balsam Seperation?

Does anyone know the effect of cement on grouped elements? Could I clean the elements and just dry stack them?

I ask because I went to use the Nikkor GN 45/2.8 and it had a nice milky quality to the image. Saw some spots in the rear, I was thinking it was maybe fungus or moisture, but upon opening it there was lots of liquid (but don't think it's the aperture grease), and I can move the two elements separately. I think the balsam has deteriorated. Question becomes how to best clean, and how to fix?

Any thoughts appreciated.

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MattParvin.com
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saxyomega90125
saxyomega90125 Junior Member • Posts: 40
Re: Cemented Groups & Balsam Seperation?

I have seen several microscope lenses that had balsam separation in a doublet. Common problem. The cheap solution is to take the group out, soak it in lab-grade acetone for a few days or lab-grade isopropyl alcohol for a week or two, then reassemble with immersion oil replacing the balsam (microscope lenses typically self-space well).

So it can be done, but if the affected group has more than two elements then things might get hairy.

I've noticed a lot of photographers aren't hardware tinkerers, so this may not be the best forum for this kind of info. Find a forum dealing with microscopes or especially binocs - some guys in Cloudy Nights do this stuff. Those are the people who can tell you how best to be rid of the old balsam and point you to a good modern cement to replace it (obviously immersion oil in a camera lens is a bad plan).

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OP (unknown member) Veteran Member • Posts: 4,469
Re: Cemented Groups & Balsam Seperation?

Thanks. Actually cleaned up well, old balsam was liquified for some reason. Just need to re-cement them. I'll do some searching.

Appreciate it.

saxyomega90125 wrote:

I have seen several microscope lenses that had balsam separation in a doublet. Common problem. The cheap solution is to take the group out, soak it in lab-grade acetone for a few days or lab-grade isopropyl alcohol for a week or two, then reassemble with immersion oil replacing the balsam (microscope lenses typically self-space well).

So it can be done, but if the affected group has more than two elements then things might get hairy.

I've noticed a lot of photographers aren't hardware tinkerers, so this may not be the best forum for this kind of info. Find a forum dealing with microscopes or especially binocs - some guys in Cloudy Nights do this stuff. Those are the people who can tell you how best to be rid of the old balsam and point you to a good modern cement to replace it (obviously immersion oil in a camera lens is a bad plan).

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MattParvin.com
It’s a lot easier to post a photo than it is to write 1,000 words...
“I believe there is nothing more disturbing than a sharp image of a fuzzy concept” ~ AA

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