The linear polarizer selection is limited, especially the smaller diameters and/or less typical sizes. I started looking for a 52mm for the Zuiko m 12-50 and ended up with a CP. One benefit is it that it will work on a SLR. I had planned to give up my Oly E510 when buying the EM-5, later decided to carry two cameras, one with a long lens and the other a short lens. My Zuiko 50MM lens is my favorite, and can now use the 52mm CP in combitaion with the E-510.