Sorting with Lens Mount All camera lenses are threaded, and the CCD camera lens mounts two industry standards, the C mount and the CS mount. Both threads have the same part, but they have different distances from the lens to the photosensitive surface. C Mount: The distance from the lens mount reference surface to the focal point is 17.526mm. CS mount: Special C mount. Remove the washer from the front of the camera before mounting the lens. The distance from the lens mounting plane to the focal point is 12.5mm. If a C mount lens is to be mounted on a CS mount camera, the lens shifter is required.