1″ 32 TPI thread
These days this is still the most common type in industrial image processing, esp. in factory automization. Mostly they are used with digital cameras like USB, Fire_Wire, Gig-E and Smart Cameras.
All C-Mount lenses have two things in common: • a thread of 1? (about 25m) in diameter and with 32 threads per Inch. • a back flange length of about 17.5mm