C-MOUNT VS. CS-MOUNT
CCTV lenses are available in two different lens mounts. C-mount lenses have a flange back distance of 17.526 mm vs. 12.5 mm for CS-mount lenses. Many of today's cameras can accept either type of lens, but it is important to make sure that the camera and the lens are set up properly. C-mount lenses can be used on CS-mount cameras by utilizing a 5 mm adapter or adjusting the camera for C-mount lenses. Because of the shorter back focal distance, CS-mount lenses can only be used on CS-mount cameras. Your picture will be out of focus if you use a CS-mount lens on a C-mount camera.