Shows Black Tab on Right (Cam) but both Chrome Cams are missing
One Cam - Leica R lenses for Leicaflex cameras with external meter are single-cam lenses (one axial cam.)
Two Cam - Leica R lenses for TTL meter Leicaflex cameras are two-cam lenses (two axial cams.)
Three Cam - Leica R lenses for Leica-R cameras (R3 - R8) are three-cam lenses (two axial & one rotational cam.)
R Only - Leica R series lens for use on the Leica R series only. This lens clearly states this on the side of the lens.
You may use any 1, 2 or 3 Cam lens on any SLR body without worry of damaging your camera or lens.
There are four lens versions:
One axial cam for use with the original Leicaflex (external metering).
Two axial cams for all Leicaflex cameras.
Two axial & one rotational cam for use on all Leicaflex and Leica R cameras.
R Cam Only with only the rotational cam, for use on the Leica R only.
However, all reflex lenses will work on any Leicaflex or Leica R camera body. If you use a one or two cam lens on a Leica R body, you must stop down the lens to take a meter reading. Otherwise the reading will be wrong. Likewise using a one cam lens on a Leicaflex with TTL metering.
If an R lens without rotational cam is used accidently on a Leica R camera, it will produce incorrect exposure. But it does not cause any physical damage to camera or lens. Simply stop down to take a correct exposure reading. A Leica R lens without a rotational cam is a Leicaflex lens.
CONVERSION OF LEICAFLEX LENSES FOR USE ON LEICA R MODELS
Existing LEICAFLEX lenses can be fitted with an additional cam for the full utilization of the LEICA R exposure facilities. The use of modified lenses on all LEICAFLEX models remains unrestricted. Modification can be made through Leica or third party Leica service facility.
CONVERSION OF LEICA R LENSES FOR ADDITIONAL USE IN LEICAFLEX MODELS
From the stated serial numbers onwards, the following lenses fit on all LEICA R models but no longer on the LEICAFLEX models. Most of these lenses can be equipped with the control cams necessary for use on the LEICAFLEX models by the Technical Service of Ernst Leitz GmbH or in authorized workshops.
CAN BE EQUIPPED FOR LEICAFLEX MODELS:
28 mm ELMARIT-R f/2.8 from 3367501
35 mm ELMARIT-R f/2.8 from 3332801
50 mm SUMMILUX-R f/1.4 from 3291801
60 mm MACRO-ELMAR-R f/2.8 from 3335501 for SL/SL2 models
80 mm SUMMILUX R f/1.4 from 3267301
90 mm SUMMICRON-R f/2 before 3381677
90 mm ELMARIT-R f/2.8 from 3384201 for SL/SL2 models only