Hi, would I use a 72 mm Infrared Filter for my 18-200mm lens? Also, has anyone had experience with this seller on Ebay: http://stores.ebay.com/y2k-INFRARED I wonder about the quality of glass since the filter only costs $35.00. I was just about to buy a HOYA until someone directing me to this site. I would truly appreciate any suggestions about getting this kind of filter since I am a newbie to my first DSLR camera.