Ready to order a GX-1 and a 12-35 lens, including a polarizer. Can I buy a regular circular [B+W] polarizer that will accept a lens cap, or must I buy the slim version for the 12-35 lens? I plan to order a 'clear' B+W filter [not slim], just wondering if the polarizer will be too thick because of the two rings? Thanks! James P.S. I did search and read a few threads, but didn't find anything addressing this specific question of slim or regular polarizer filter.