I have opted to post this in Equipment reviews and discussion simply due to the fact I was a little caught off guard at the idea of howmany people have never heard of fungus growing inside a lens. I playfully call it "athletes lens" but there is nothing playful about it. Fungus will eat away at the coating on your glass and eventually bring about the death of your investment. It can be cleaned out but it's best to just prevent it as it will change the behavior of the lens, and that is if you can save it at all. [Below you will see early fungus growth on the front element of a Canon FD 135mm, Ø - 55mm lens] See it bigger here Lens maintenance is important, it goes well beyond merely keeping it clean. Do try to keep your lenses in an environment that is not suitable for fungus. Feel free to either comment on the image or give advise on prevention or removal of fungal growth in a lens.