C mount
![12 mm f/1.2 C-mount lens with a C-mount–to–CS-mount adapter](/Images/godic/202501/05/C_mount_lens_Pentax_12mm_f1.25831.jpg")
A C mount is a type of lens mount commonly found on 16 mm movie cameras, closed-circuit television cameras, machine vision cameras and microscope phototubes.
C-mount lenses provide a male thread, which mates with a female thread on the camera. The thread is nominally 1.000 inch (25.4 mm) 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 millimetres (0.6900 in) for a C mount.