Hello-- I'm looking for a quality circular polarizer for my recent purchase of the 12-40. B&H recommended the B+W Kaesemann XS-Pro Circular Polarizer MRC Nano Filter, but I took a look at the reviews and one reviewer found that it touched the lens surface. He posted about it on that other site and another person described the same issue. http://www.dpreview.com/forums/thread/3644367 It's not clear if the issue is the lens or the filter. I'd like to avoid trying it, only to possibly damage the lens, and then having to return it. I welcome your comments and suggestions. Thanks!