Recently, I took out my G5, kit zoom and 45-200 mm lens. The 45-200 mm was having trouble focusing at a distance, but seemed to do ok on subjects that were closer. Later, trying to troubleshoot, I took off the polarizer and it seemed to work fine. My questions: Does a polarizer affect autofocus? Does a cheap polarizer affect autofocus? The filter that seemed to be the problem is a Nicna Pro1-D Wide Band Pro-MC C-PL(W) from Rainbow Images. It wasn't very expensive but, if it affects focus, it is worthless. My other polarizer, a Rocketfish CPL from Best Buy seems fine. My plan was to have polarizers on each lens, since nearly all of my shooting is outdoors. Anyone else have similar issues, including this brand?