C-Mount and CS-Mount Lenses

C-mount and CS-mount are medium format screw mount lenses. Unlike board mount lenses, these lenses typically feature variable focus and aperture capabilities. All C/CS mount lenses have the same thread diameter of 25.4mm (1”). The image circle they produce ranges from 6.6mm to 17.6mm.

C-Mount and CS-Mount Lens Applications

C-mount and CS-mount lenses are commonly used in machine vision systems, for a range of applications including parts inspection and parts counting on assembly lines. They are also widely used for closed-circuit TV cameras and security cameras.

CS-Mount vs. C-Mount: What’s the Difference?

C-mount and CS-mount lenses both have male threads on the same outer-diameter mount. They both use identical threads, with a pitch of 0.794mm (32 threads per inch). The difference between the two lens formats is the flange back distance. C-mount lenses have a flange back distance of 17.526mm, while CS-mount lenses have a flange with a depth of 12.526mm. C-mount lenses can be used in a CS-type lens mount with a 5mm thick adapter ring to secure them, but CS-mount lenses cannot be used in a C-type lens mount because the deeper lens mount will hold the lens too far away, placing the focal plane in front of the image sensor, and preventing it from focusing properly.

C/CS Lens Types and Usage

C-mount and CS-mount camera lenses are available both as fixed focal-length lenses and as zoom lenses with variable focal lengths. These lenses are available in a variety of focal lengths from fisheye lenses through telephoto lenses, and with special optics optimized for SWIR (short-wave infrared) applications.