Re: [Leica] fog up lens

["Joseph Codispoti" <joecodi@clearsightusa.com>]

- ----- Original Message -----
From: <kyfung@kaifa.com.hk>

> My 35 summicron fogged up (at leat it looked like fog to me, no
resemblance
> to fungus) on both the front and rear surface, I saw that when I shone a
> flash light through lens. Can't tell if any one of those surfaces behind
> thye first is affected but at leat they look clean. I clean it with with a
> cloth and a lens cleaning solution from Kodak. It appeared that it's gone.
> Then I inspect it a day later and the fog is still there. Any know why it
> fog up up and how can clean it as to also prevent it from happening again.
> Any advise is appreciated. TIA.
> regards,
> ky fung
> Kaifa Magnetics
> Failure Analysis
> Tel: (86-755) 327-5000 Ext. 33215
> Fax: (86-755) 327-5376


Ky,

I did not respond earlier because of the nature of you problem, which I
attributed to a normally dirty lens. After the last post regarding alcohol,
I would like to state a few facts:

Kodak lens cleaner leaves more residue than it removes.

In reality, alcohol does not clean much more than water. It is used
extensively, especially as an additive to cleaners, because of its property
to dry very quickly. It too can leave residue. Alcohol would be fine for
cleaning the lens provided that you follow up with a good lens cleaner to
eliminate alcohol residue.
You could try also a mild solution of bleach (1 liter distilled water to
30ml of bleach) and finish with a good cleaner as above.

Most likely your problem is deteriorated (discolored) coating that may not
be possible to remove. Applying any liquid gives you the impression that
cleaning is taking place only to revert to fog once the lens is dry.
In any case, take a look at my suggestion for keeping lenses clean at
www.clearsightusa.com , in particular the "lens maintenance" section.

Good luck,

Joseph Codispoti




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