CSmount

CSmount is a lens mount standard used primarily in surveillance cameras and machine-vision systems. It is a variant of the C-mount designed to provide a shorter flange focal distance, enabling the use of interchangeable lenses on compact cameras with smaller image sensors. The mount uses a 1-inch diameter screw thread with 32 threads per inch (1"-32 UN). The principal distinction from C-mount is the flange focal distance: CS-mount specifies 12.5 mm, while C-mount specifies 17.526 mm. This difference affects lens compatibility and focusing behavior.

In practice, the shorter back focus of CS-mount facilitates thinner camera layouts and tighter optical designs. Many CS-mount lenses are designed specifically for 1" and smaller sensors and include standard CCTV varieties, as well as infrared variants. The same thread standard means that C-mount lenses can be used on CS-mount cameras with a 5 mm adapter that restores the proper flange distance; CS-mount lenses are generally not compatible with C-mount cameras without specialized hardware or optical correction, since the back focus would be incorrect.

CSmount is widely used in closed-circuit television, robotics, and other industrial imaging applications where compact form factor and lens interchangeability are valued. It competes with other small-lens mounts such as M12 for board-level cameras. The standard remains common in legacy CCTV gear and newer budget machine-vision cameras, though some manufacturers offer alternative mounts for higher-resolution sensors.