I recently picked up a 135mm Wide Field Ektar off of the famous auction site. I am curious to find out the proper attachment size for filters for this lense. I suspect that it is a series size. It is just a little bigger than 52mm. Can anyone steer me to a source of adapter rings to adapt this lens to a 58mm filter? When I closely inspected the lens, I noticed quite a few light scratches on the back lens element. Will this greatly effect my image quality as to sharpness and contrast? The seller assured me that these were only in the coating and should not have any effect on image quality. My plan is to do a direct comparison with a 135mm Symmar that is a known quanity and has performed well for me in the past. Any other comments on this lens would be greatly appreciated.