Wow! Thanks for giving me pause on the buying of UV filters. From now on I'll only buy non-UV for protecting my lenses.I try to avoid lenses with fungus . My theory is the old lenses develop fungus in part due to the almost always present UV filter. There are other reasons that fungus thrive, e.g. they've been around longer so more chance to get it. I've read that exposing them to sunlight helps to minimize.