Leica R is the SLR cameras from Leica, the WYSIWYG (WhatYourSeeIsWhatYoyGet) camera where you look through the lens of the camera via a mirror, thus seeing the exact picture you will get. See the Leica Lens Comendium for an overview. There exist many intersting older lenses with a special look.

Only you can't get the lenses 6-bit coded at the factory (as the 6-bit coding system doesn't support older lenses). Everything will work, the focus, the aperture and all. In any case, these still exist as second-hand and will fit any screw-thread Leica camera, and also (via an adapter) any Leica M camera, including the digital rangefinders Leica M8, M8.2, Leica M9 and Leica M 240. Thoses are some times referred to as V lenses. The older Leica M was with screw-thread and not the M bayonet lens mount. Leica M 240 with Leica 50mm Summicron-M f/2.0 II Next to me the proud owner who acutally uses the kit every day. Me with an elated expression holding the Leica Hermes speical edition bag (announced in Berlin, May 2012) with the Leica M9 Hermes inside and the three lenses (50/0.95, 50/1.4 and 28/2.0). This 18MP black and white only camera was originally released in 2012 in black, and in May 2014 in silver chrome finish as well. The Leica M Monochrom in silver chrome (as of May 2014). Nevertheless, it gave a lot of free PR in the fashion blogs where Leica is a regular guest as the probably most stylish camera in he world).

The special edition Leica M8 white that came out in spring of 2009 (and which divided the waters in terms of who amongst the Leica fan crowd thought it was a cool camera and others who felt it was the absolute degrading of classic Leica style. All of the M cameras are rangefinder cameras, meaning one looks not through the lens but through a separate window. Leica M is the classic Leica from 1925 up to today's M6, M7, MP film cameras (with an addition of the Leica M-A in May 2014 as the brand new remake of a Leica film camera) and the digital Leica M8, Leica M8.2, Leica M9, Leica M9-P, Leica M-E, Leica MM ( M Monochrom) and simply Leica M (as of 2013 though it is called ' Leica M Typ 240'). If new to Leica, one might get confused about the M and the R and the D and the C and the S letters:

Leica Luftwaffe Serial Numbers