Leica R bayonet

The Leica R bayonet mount is a camera lens mount system introduced by Leitz in 1964. The R 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. 3 cam lenses are compatible with all of the Leica SLR cameras, while R-only lenses have a slightly different mount shape that will not fit on the earlier cameras.[1][2]

Leica R-mount
A Leicaflex SL and R mount 50 mm lens
TypeBayonet
Tabs3
Flange47 mm
ConnectorsElectrical contacts for lens properties on later models

The flange focal distance between mount and film is 47 mm.[3]

On 5 March 2009, Leica announced plans to cease production of its R-Series manual focus SLR and lenses.[4][5]

R Mount camera bodies

Leicaflex
Image Name Year Exposure Notes
 Leicaflex 1964–1968 Manual  • The first R mount SLR camera
 Leicaflex SL 1968–1974 Manual
Through-the-lens metering (TTL)		  • "SL" standing for selective light
 Leicaflex SL2 1974–1976 Manual
TTL		  • More sensitive exposure meter and changes to the mirror hinging for wide angle lenses

Leica R
Image Name Year Exposure Notes
 Leica R3 1976–1979 Manual
Aperture priority		  • Developed in cooperation with Minolta.

 • Based on the Minolta XE.

 Leica R4 1980–1986 Manual
Aperture priority semi automatic
Shutter priority semi automatic
Program automatic		  • Based on the Minolta Minolta XD-7.
 Leica R5 1986–1991 Manual
Aperture priority semi automatic
Shutter priority semi automatic
Program automatic		  • Automatic TTL flash exposure measurement
 Leica R6 1987–1996 Manual
  • Mechanical shutter, relied on battery power only for the built-in light meter.
 Leica R7 1991–1996 Manual
Aperture priority semi automatic
Shutter priority semi automatic
Program automatic		  • Complete flash automation.
 Leica R8 1996–2002 Manual
Aperture priority semi automatic
Shutter priority semi automatic
Program fully automatic
Flash pre exposure measurement		  • Intended as a clean break from the previous generation of Leica R cameras and designed in house.
 Leica R9 2002–2009 Manual
Aperture priority semi automatic
Shutter priority semi automatic
Program fully automatic
Flash pre exposure measurement		  • Electronic changes included the ability to tune the sensitivity of matrix metering.

R mount lenses
1 cam

The original Leicaflex 1 cam lenses have a single sloped cam that communicates aperture setting to the camera. They can be used on later SL / SL2 and R-series cameras in stop-down metering mode only. Leica do not recommend that 1 cam lenses be used on R8 or R9 cameras because of possible damage to the cameras' ROM contacts. 1 cam lenses may be fitted with later 2 cams, 3 cams, or R cam + ROM contacts (replacing the sloped cams).[6]

2 cam

2 cam lenses have two sloped cams for the Leicaflex SL and SL2 with TTL metering and are fully compatible with the original Leicaflex. They can be used on R series cameras with the same limitation and warning as 1 cam lenses and may also be fitted with later cams.[6]

3 cam

3 cam lenses were introduced with R series cameras and have the earlier sloped cams and a third stepped "R-Cam" that communicates aperture information. They will work with all Leica SLR models since they have all three mechanical connections.[6]

R only

These lenses only have the stepped R-cam and only work on R-series cameras. The mount is deliberately slightly incompatible with Leicaflex models and will not fit. They may be converted to ROM by a technician.[6]

ROM

These only have the stepped R-cam plus electrical contacts communicating focal length to the camera. This is only supported on the R8/R9 although the lenses are fully compatible with all R-series cameras. The additional information is used in flash metering and communicated to the flash unit where it can be used to set power and flash zoom correctly and also to the optional Digital Module allowing lens focal length to be recorded with other image data.[6]

Earlier 1, 2, or 3 cam lenses may be upgraded to ROM but this entails removal of both sloped cams, meaning that the lens will no longer be compatible with Leicaflex series cameras.

Table
Leicaflex SL/SL2 R3-R7 R8-R9
1 Cam !
2 Cam !
3 Cam
R Only
ROM +
+ full aperture metering + ROM data
full aperture metering
stop-down metering
! stop-down metering, possible damage to camera contacts
will not fit

Use with 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, and at least two manufacturers make replacement mounts, allowing many Leica R lenses to be used directly on various camera systems, such as Nikon F mount cameras. For this purpose, the cams need to be removed, which is not always possible (e.g. early Elmarit-R f/2.8 35mm). The mounting flange may then need to be machined to allow free movement of the remaining cam. Sometimes, it is wise to refit the inner black anti-reflection ring, to avoid reflections within the focus mechanism (e.g. Elmarit-R f/2.8 90mm or Elmarit-R f/2.8 135mm). A further point of consideration is whether the protrusion on the rear lens block will engage with the mirror of the target SLR. For some Nikon cameras, this may be an issue.

Chips can also be attached to provide focal length and maximum aperture recognition in the camera body, which provides Exif in digital cameras.

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.

See also
Wikimedia Commons has media related to Leica R.
Wikimedia Commons has media related to Leica R lenses.

References
  1. "Leica R-System Mount". apotelyt.com. Retrieved 13 April 2019.
  2. Chapman, Gerry Yemen, S. Venkataraman and Bill (4 April 2014). "Why Leica Camera decided to leave its beloved R series behind". The Washington Post. Retrieved 25 December 2019.{{cite web}}: CS1 maint: multiple names: authors list (link)
  3. "Leica R-Mount - One / Two / Three-Cam / ROM". www.apotelyt.com. Retrieved 27 November 2019.
  4. "Leica R10 - The R-system flagship that did not materialize". www.apotelyt.com. Retrieved 27 November 2019.
  5. "End of the Line for the Leica R System?". The Online Photographer. Retrieved 27 November 2019.
  6. "Leica R Lenses: Understanding Cams - Spotlight". www.keh.com. Retrieved 27 November 2019.
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