What exactly is fungus in a lens? I assume that is is not mini toadstools growing out from the edges, like something from Voyage to the Centre of the Earth. I would like to sell a couple of lenses and wish to describe them accurately. I look into them and see layers of multicoloured (presumably multicoating) reflections, and little images of the things on my desk behind them. I have tried white and black paper behind, but I cannot see anything inside! What am I looking for?
Lens fungus really is a fungus, encouraged by trapped moisture and feeding on lens coatings, even etching the glass. Unfortunately, usually fatal.
Oh shoot! That's awful! Thanks for the link. It really is about real biological fungus. Luckily there is none of that stuff in these lenses. OK, thank you let's move on .........
I would never ever buy a lens with it, it can affect other lenses owned.
Ensure it is stated in an advert
For the price people spend for these lenses, you would think the would be sealed better. It had to get in there some how. Never heard of such a thing till I read this post.
I like to keep a few dessicant packs in my camera bags, you know, those little packets that come packaged with electronic devices and shoe boxes and other things. These will absorb moisture from the air and thus, help to keep your lenses and bodies moisture and fungus free.
Can't be too careful. I just got a very nice used lens that came with a Hoya skylight filter attached. Accidentally discovered when examining the filter, fungus. Hadn't spread to the lens yet, but there's one filter that's bye-bye.
Freakin' Filter Fungus Fortunately Found. About 1 mm glob, scanned at 1200 dpi.
Nasty. How do you spot the stuff inside the lens? Put a white or black card behind? Shine a light through the front or the back? All I can see is reflections from the glass surfaces!
If you have fungus bad enough to affect image quality, you'll see it by looking through the lens. If you can't see it, it probably won't degrade your pictures.
It's like internal dust, that many lenses have. It's there, but so far out of focus it won't matter. Just that fungus can get worse and eventually destroy the optics.
My example on a filter would probably have no effect on image quality. I just don't want to take a chance of it spreading to the lens. I only saw it when I was examining the surfaces with a magnifier and fogged up the filter with my breath.
In order to see it at all in the image, it was scanned at 1200 dpi on a flatbed. I had to keep breathing on it to keep it fogged during the scan to see it at all. Damn near passed out. :) Then converted the image to negative and played with the gamma and contrast.
Brief summary: Fungal spores are tiny enough to ride on dust particles. And they are everywhere! Typical spore count is 500 or more per cubic meter of air. They're part of nature's way of helping with decomposition. Any lens that changes length focusing or zooming is sucking air in and out to avoid a vacuum effect. Only way to avoid infestation is to restrict your shooting to an indoor filtered environment with constant UV decon. (What fun is that?) Most of the time you won't even know they're there. They can be killed off with combinations of UV light, ozone, peroxide and other means. If they haven't oozed enough acid to etch the glass or coatings, they can be removed without negative effect.
So just shoot away, and take normal precautions to eliminate moistue in storage. Don't lose too much sleep worrying about it; if it gets bad enough to affect your pictures, you'll see it!
Thanks very much! I'll keep a lookout.