Leica R bayonet

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A Leica R series doubler, with the female part of in bayonet mount...

...and the male part.

The Leica R bayonet lens mount is the standard method of connecting a lens to the Leica R series of 35 mm single-lens reflex cameras. The mount is descended from those used for the Leicaflex, Leicaflex SL and Leicaflex SL2 SLR cameras, but differs in the cams used to communicate lens aperture information to the camera. Some lenses are compatible with all of the Leica SLR cameras, while R-only lenses have a slightly different mount shape which will not fit on the earlier cameras.

The flange focal distance between mount and film is 47 mm.

1 Variants
2 On other cameras
3 See also

[edit] Variants

[edit] One-cam lenses

One-cam lenses have a cam that only works to communicate aperture information to the original Leicaflex camera. They can be used on later cameras in stop-down metering mode only. Leica do not recommend that they be used on R8 or R9 cameras because if the cam is out of specification it may damage those cameras' ROM contacts. One-cam lenses may be converted to work fully on later cameras.

[edit] Two-cam lenses

Two-cam lenses have cams for the Leicaflex and also for the SL and SL2. They can be used on R cameras in stop-down metering mode; again, Leica does not recommend that they be used on the R8/R9, and they can be modified to work fully with R cameras.

[edit] Three-cam lenses

These have a third "R-Cam" fitted that communicates aperture information to R-series cameras. They work with all Leica SLR models, because they have all three methods of communication.

[edit] R-only lenses

These only have the R-cam, and only work on R-series cameras. The mount is deliberately incompatible with the Leicaflex models. May be converted to three-cam by a technician.

[edit] ROM lenses

These only have the R-cam, but in addition have electrical contacts allowing the lenses to communicate information to the camera, such as the lens' focal length. This is only supported on the R8/R9, although the lenses will also mount and work on earlier R cameras. The info is used in flash metering and also communicated to the flash unit, where it can be used to set power and flash zoom correctly.

[edit] On other cameras

The flange focal distance of 47 mm is fairly large, meaning that few other systems' lenses can be adapted to fit on a Leica R and retain infinity focus, but R lenses can be converted to other systems. The distance is only 0.5 mm larger than the Nikon F-mount, which is not sufficient to make a workable adapter; however, at least one Nikon camera has been modified with a Leica R bayonet mount to take R lenses.

A number of manufacturers have produced adapters to allow Canon EOS cameras to take R lenses; these operate only in stop-down metering mode, but function well when rapid operation is not required.