Nikon F-Mount

Developed by Nikon in 1959, the F Mount is an interchangeable flange-mount system designed for attaching lenses and other types of adapters to film or digital cameras. The F Mount bayonet flange is commonly used for large format sensor scientific and industrial camera models.

The F Mount system features a three lug bayonet-style mount with a 44mm diameter. F Mount adapters have tabs around their bases that fit securely into the appropriately sized recesses in a camera F Mount. A slight turn then locks the lens/adapter unit into place with a spring-loaded pin.

F Mount adapters and lenses have a flange to focal plane distance of 46.5mm. This long back focal distance (between the lens mounting plane and the imaging plane) allows them to be converted to C Mount lenses or C Mount adapters with the addition of an inexpensive “F” to “C” adapter ring. A C Mount is the type of lens mount most commonly found on trinocular phototubes and CCTV cameras.

Cameras use the F Mount over the common C Mount for two reasons: 1) When imaging sensors exceed the 4/3” C-mount size limit. 2) When additional space is needed between the lens mount flange and the image sensor for optical elements.