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05-26-2020, 02:31 PM   #1
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Alien life forms...fungus in the prism

I cant see how fungus can get into a prism and even less able to see how it can grow in solid glass. Makes you think ‘The Thing’ might not be so unbelievable after all. And........eeeeeek I have fungus in a prism.

Its only tiny right now but quite definitely on the move. Has anyone ever successfully killed it in a prism ? I am thinking of a monster hit of UV but if the stuff can survive inside a block of glass I am not so sure its worth the effort to try and nuke it with UV.

Thankfully its in an OM1 which would be an easy job to replace the prism in if thats the way it has to be.

War stories welcome

05-26-2020, 02:57 PM   #2
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Is it possible that it is prism de-silvering?
05-26-2020, 02:57 PM   #3
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QuoteOriginally posted by Astro-Baby Quote
War stories welcome
I had a M series 40mm f2.8 once that had a spider inside.
05-26-2020, 03:28 PM - 1 Like   #4
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Fungus can infestate and grow absolutely anywhere, as long as the conditions for its growth are favourable. A prism isn't airtight, nor are lenses.

Blasting fungus with the supposed wonderkind of UV in any dose isn't the be all and end all of fungus treatment and, especially elimination. The trouble is the etching that is so often left after physical removal of fungus (proprietary chemical solutions); on lens elements the only way of overcoming etching is resurfacing, re-polishing and coating, and it is not cost effective for old lenses, nor cameras.

If it is an active, motile fungal infection, there is a realistic chance it has migrated elsewhere too.

05-26-2020, 05:09 PM   #5
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QuoteOriginally posted by sergysergy Quote
Is it possible that it is prism de-silvering?

IIRC this is pretty common on this model.

05-26-2020, 11:02 PM   #6
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Nope its not desilvering its definite fungus, the desilvering in OMs is usually caused by decaying foam and this one has has its foam removed and was completely cleaned of residue about 2 years ago. This has sprung up recently.

Unlike a lens where there would be some access to give it a chemical blast of peroxide this is actually inside the prism, not on an outer edge so there is no access at all leaving UV as the only possible cure. I have been blatting it with sunlight but as far as I can see after around 5 days the sunlight has had zero effect and may be making it worse.

Just wondered if anyone has had any success. Its quite tiny at the moment and only at the extreme edge of the view so of there is any chance of nailing the stuff its now.

Might buy a UV lamp and see what happens.
05-27-2020, 04:36 AM   #7
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The fungus is definitely not inside the glass, that is not physically possible.

It may have etched the surface of the glass or got between the glass and the silvering. Whilst strong UV light may kill the fungus and stop it growing further it will not remove it or any damage it has done.
If it cannot be cleaned manually from the surface then the only option is to replace the prism.

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