I recently picked up a couple of Pentax CCTV c-mount lenses but I am having problems with focusing beyond just a few inches from the camera. I have a OM-D and an E-PL1 and both have the same results. My c-mount adapter is from fotodiox. While I understand the vignetting I don't understand why I am having difficulty achieving focus on objects that are farther away than 5 inches or less from my camera. I have removed the focus screws in both lenses so I can move the focus ring. Does anyone have any pointers?