Nikon S-mount

Nikon S-mount
The Nikon S-mount seen as part of the 1957 Nikon SP. The distance scale is for use with lenses using the internal bayonet.
TypeInternal and External Bayonet
External diameter36.5 mm (internal bayonet) and 49 mm (external bayonet)
Tabs3
Flange34.85 mm

The Nikon S-mount is a type of interchangeable lens mount used by a series of Nikon 35 mm rangefinder cameras (Nikon I, Nikon M, Nikon S, Nikon S2, Nikon SP, Nikon S3, Nikon S4). The lenses were sold under the name Nikkor.