http://www.temple.edu/biomed/tt3.html
A few years ago I read an article by someone who claimed to have destroyed
fungus on a lens element by opening the lens to the widest aperture and
placing it in a position where sunlight could shine through the lens. The UV
rays kill the fungus. He claimed that it worked well if the fungus was not too
advanced. I tried it on a lens with a slight fungal bloom and it killed the
fungus. I have had the lens for several years now and have had no further
fungal growth. It would be advisable not to allow the lens to get too hot.
Wouldn't want to risk messing up the cement binding lens elements. The site
above makes a brief reference to this method, but doesn't think it effective
on a badly fungused lens element.
Robert
>
> swisspace wrote:
>
> > How do I tell the difference, i just looked at the front element in
> > bright light and you dont see anything yet when i looked before it has
> > light spots that looked as if they could be fungal blooms, but having
> > not seen an infected lens before I don't know how to tell.
> -------------------------------------
>
> Look through the lens from both ends using a flashlight pointing toward
> your eye from the opposite end. This is a very severe test so look
> through some of your other lenses that you *think* are OK as well.
> You'll probably spot all sorts of dust and debris some of which may be
> small black paint flecks. The dust and debris may be unsightly but does
> no optical harm of any consequence.
>
> Fungus will show itself as a spidery web or as an irregularly shaped and
> possibly irregularly colored grayish blotch. Remember if you need
> glasses for reading that the distance from your eye of the defects
> you're looking for may not be withing the focusing ability of your eye.
> Also, the apparent distance will be different from the actual distance
> since you're looking through one or more lens elements.
>
> A small amount of fungus will not do any optical harm of conseqence
> either except that it may very well grow in the future. It also eats
> coatings under the glass and may etch the glass itself since it produces
> acid byproducts. The biggest harm is to your wallet. Even if there's a
> tiny spot of fungus which is of no optical consequence the lens becomes
> next to worthless.
>
> Chuck Norcutt
>
>
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