C and CS-mount are both threaded lens mounts found on a majority of industrial CCD cameras and lenses. The difference between C and CS-mount equipment is called the flange back distance.  The flange back distance is the distance between where the lens comes in contact with the camera (the flange) and where the CCD sensor must be positioned (the focal plane or focal point).

 

12 mm f/1.2 C-Mount lens with a C-Mount to CS-Mount adapter

On C-mount lenses, the flange back distance is 17.52mm (0.69 inch) and on CS-mount lenses it is 12.52mm (0.49). Both the C-Mount and CS-Mount lenses are 1 inch in diameter with 32 threads per inch (TPI). Unless the camera has a built-in flange-back adjusting ring, a C-Ring (5mm spacer ring) is required when a C-Mount lens is to be mounted to a CS-Mount camera.

One thing to remember is that CS-Mount cameras are always compatible with C- or CS-Mount lenses but C-Mount cameras are not compatible with CS-Mount lenses.  Basically, if you have a CS-mount camera and a C-mount lens, you can add a 5mm spacer (C-ring) to obtain the correct focus but if you have a C-mount camera and a CS-mount lens, correct focus cannot be achieved.

Share Button