I recently bought a fairly expensive lens, and the salesman was trying to talk me into buying a heliopan UV filter with the lens, more as a means to protect the surface of the lens than anything. Ive used them before, but stopped because I was getting lens flare and would always forget to take it off to avoid it. Anyone here use one? Do you feel its really worth buying the more expensive ones? Aside from flare, do they affect image quality?