Sigma SA-mount

The Sigma SA-mount is a lens mount designed by the Sigma Corporation of Japan for use on their single-lens reflex cameras. The SA mount uses a bayonet mount which is physically similar to the Pentax K-mount but uses a flange focal distance of 44 mm, identical to that of the Canon EF-lens mount.
The mount uses electrical communication between body and lens, like the EF-mount, and in fact uses the same signalling lines and protocol as the EF-mount, despite the physical incompatibility. Sigma has long produced EF-mount lenses for Canon cameras, and thus had the ability to use this protocol.
All Sigma SLRs and DSLRs can use manual focus lenses too, which have no electrical communication between body and lens.

Compatibility

Nikon F-mount and M42-mount lenses can be fitted and used via easily available lens mount adapters. Pentax K-mount (PK) lenses can be fitted straight onto the SA-mount, after the protruding AA lever and AA protector outcrop are removed, though the fit is slightly loose as the SA-mount has a slightly bigger bore than the PK-mount.

Adaptation of lenses for other bayonet mounts on Sigma cameras

Some Sigma DSLR users have become adept at converting high quality manual focus lenses to fit the SA-mount. One such user in the UK, has successfully converted Nikon, Contax Carl Zeiss, Minolta MD, Canon FL and FD lenses to fit the SA-mount. Others have even produced replacement mounting plates for Sigma DSLRs, which convert them to either Nikon or Leica R-mount, or replaced the mount entirely with an EF-mount.

Camera Bodies

Body	Release Date	Sensor
Film (36 x 24 mm)
SA-300	1993	n/a
SA-300N	1994	n/a
SA-5	1997	n/a
SA-7	2001	n/a
SA-9	2001	n/a
SA-7N	2002	n/a
Digital (20.7 x 13.8 mm)
SD9	Oct. 2002	Foveon X3, 2268 x 1512 pixels
SD10	Dec. 2003	Foveon X3 2268 x 1512 pixels
SD14	Mar. 2007	Foveon X3, 2640 x 1760 pixels
SD15	Jun. 2010	Foveon X3, 2640 x 1760 pixels
Digital (24 x 16 mm)
SD1	Feb. 2012	Foveon X3, 4800 x 3200 pixels

Lenses

All SLR lenses manufactured by Sigma since 1993 are available for the SA-mount. A partial listing can be found here.