Q.) I'm using a Teledyne/FLIR/PointGrey Blackfly C/CS mount camera. Why won't my lens focus? First, please check out lens mount compatibility blog post. Second, we regre to inform you that the mechanical engineering team at Teledyne/FLIR/PG did not consider lenses when they designed their camera's housing. The IR cut off filter which is installed on your camera is ~8-10mm distance from the sensor. As a result, any lens with a MBFL<10mm may not be able to focus on the camera, including some CS mount lenses. To bring the lens into focus, you will have to remove this IR filter and use an IR filter installed in the lens. To remove the filter, please see this FLIR knowledge base articleand contact them. Be aware removal will void your warranty.