I'll add this. I have destroyed filters by simply cleaning them. By destroyed, I mean lightly scratched. These are probably not the same top quality glass found in a lens, however. But riflescopes? I have seen many from Nikon's to Weavers, to Pentax's and Leupolds, which ARE good quality glass, destroyed by even the most careful cleaning. They were still usable but if I spend 2000.00 on a Ziess riflescope, and then end up with hairline blimishes due to dust particles I did not see, I am going to go ballastic. I have a problem believing that Top quality coated UV filters do any harm at all to image quality and certainly not enough for the human eye to detect. Cheap ass 5 buck filters are another story. I agree with the member who stated that it's best not to clean the front element unless its absolutely necessary and a good UV filter will prolong this necessity for a very, very long time. When I clean a front lens element, I do it with a brand new Nikon rag designed specifically for this, after and only after blowing the element off with a rocket blower and light use of a lens brush, after which the UV filter goes back on. I have lenses that that I've had for years that have never been cleaned nor do they need being cleaned, thanks to UV filters. That's the only reason I use them. Not that I disagree with everyone who doesn't use UV filters and their reasoning behind it. This is only my take on it.