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Re: [OM] Lens Fungus

Subject: Re: [OM] Lens Fungus
From: Garth Wood <garth@xxxxxxxxxxxxxxx>
Date: Wed, 10 Nov 1999 17:27:47 -0700
At 01:20 PM 11/10/99 -0500, you wrote:
>I have just sent two lenses to KEH for sale and was surprised to learn
>that one of them had fungus in the lens.  My questions are as follows.
>
>1.  Does fungus coat the lens elements uniformly because I didn't notice
>any "specks" of fungus?

No.  Some fungal infections appear like uneven "blooms" on the lens, others 
more like spidery tracks.  Probably depends on the species.  As well, poor 
cleaning of the front or rear elements can sometimes be mistaken for a fungal 
"bloom" inside the lens (I did this recently with my Zuiko 100/2.0 -- turns out 
it was inadequate cleaning of the front element, which, upon inspection from 
the rear using a strong light source, made me believe I might have fungus 
inside the lens; a more thorough inspection revealed the real problem).

>2.  Anybody have any recent purchases of new lenses come down with
>fungus because now I'm afraid my new lenses are at risk?

Define "new."  I bought a used Vivitar 90/2.5 Macro two years ago on eBay which 
had fungus in it (I forgot to ask, and the seller ever-so-kindly neglected to 
inform me), yet still takes really good photos.  I can't get anyone to clean 
the fungus out of it, so I have to live with it.  It lowers the effective 
contrast of the lens, but doesn't otherwise resolve.     

>3.  What measures can I take to prevent fungus from attacking my lenses?

There are lots of home remedies, but keep these points in mind:

1. Fungal spores are everywhere, and are most likely already inside your lens.  
This, in itself, is not a cause for worry.

2. Fungi love dark, cool, moist conditions.  Removing even one of those three 
variables from their environment virtually prevents the spores from growing at 
all.  You can store your lenses in airtight bags with silica gel dessicant, for 
example, keeping the humidity under 40% relative, and this will deny the spores 
necessary moisture to bloom.  This is what I do.  You can also expose them to 
UV for a few hours each week, which hinders growth or may outright kill the 
spores (no idea what it does to the non-glass, non-metal parts of your 
lens(es), though).

I store my lenses in heavy plastic bags with rechargeable dessicant cartridges 
which I bought on the Web, and I also keep a small, inexpensive hygrometer 
(humidity indicator, $7.95 CDN at Lee Valley) in with the lenses.  When the 
cartridges' indicator windows turn pink and the hygrometer reads 350r so, the 
cartridges come out and get re-charged in the oven, and then they go back into 
the plastic bags with the lenses.  Humidity drops below 20% and I'm a happy 
camper.

Garth


 
"A bad day doing photography is better
 than a good day doing just about 
 anything else."
 
The Unofficial Olympus Web Photo Gallery at:

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