Sorry, I'll introduce my interest. I have owned cameras for 60 years. I am not a photographer but I take pictures. I like to own nice equipment whether it is functional or not. At the present time my interest is in owning Nikon film cameras and lenses. I frequent ebay and occasionally I'll actually bid for something (usually) cheap. Some would argue I'm a collector not a photographer. However, I do take photographs though the end result leaves a good deal to be desired. That is where I derive my interest in photography and why I joined this forum so I hope members will not be upset by my honesty. I see a term "fungus" usually on the inside of a lens. How detrimental is fungus to a lens please? Is it possible to clean out? How difficult is it to dismantle a lens and is it actually worth the risk? Thank you,.