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Old February 11th 11, 04:03 AM posted to
David Nebenzahl
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Posts: 1,353
Default Lens Cell Cleaning

On 2/10/2011 7:50 PM spake thus:

On 2/10/2011 10:14 PM, David Nebenzahl wrote:

On 2/10/2011 4:54 PM Cheesehead spake thus:

On Feb 10, 4:53 pm, David Nebenzahl

It's not clear you've tried to remove and clean the rear cell;
have you? If not, you should. What've you got to lose? If in
fact the cement is clouded (which I think is probably
unlikely), you've got to replace the thing anyhow (or have it
recemented), so why not just pull it out and clean it? It ain't
rocket surgery, you know.

I have, of course, unscrewed the cell from the shutter and
observed that the fogging is inside the rear cell.

Well, did you try to clean the outer surfaces? Sorry, not clear
from your postings.

I'm confused on his post as well. It's a triplet and as such the rear
"cell" would be a single element. I suppose the glass itself -could- be
bad and have fogging inside the single element itself?

No, it could not. Glass itself doesn't fog, at least not under most
conventional terrestrial* conditions.

Or the coating is screwed up?

Is that lens even coated? Even if so, coatings don't generally fog.
Either the lens surfaces themselves are schmutzified (that's the
technical term), or it's a cemented element and the cement has gone bad.

If the latter, the elements can be separated and recemented. This
process has actually been described here by R. Knoppow. People like S.
Grimes can also perform this particular kind of alchemy.

* Sorry, been reading about black holes and other weird cosmological
phenomena, where anything can happen.

Comment on quaint Usenet customs, from Usenet:

To me, the *plonk...* reminds me of the old man at the public hearing
who stands to make his point, then removes his hearing aid as a sign
that he is not going to hear any rebuttals.