C/CS Mount Camera

C mount lenses provide a male thread which mates with a female thread on the camera. The thread is nominally 1 inch in diameter, with 32 threads per inch, designated as "1/32 UN 2A" in the ANSI B1.1 standard for unified screw threads. The flange focal distance is 17.526 mm (0.69 inches) for a C mount, 12.52 mm for the otherwise identical CS mount. The advantage to a C Mount Camera is that the lens can be changed. If you need to see further than 35 or 40 ft then you'll need a c mount camera with a special lens. C Mount lenses are available from 4mm to 50mm. A 4mm lens provides facial detail and a 70 degree angle of view focused up to about 35 ft. An example of where you might use a fixed 4mm lens is in a small office, or at home to focus on your driveway.