The Leica and Leitz Lens Compendium by Thorsten Overgaard

Leica fixed zoom lenses

Fixed zoom lenses on cameras

Leica Screw Mount Lenses "M39" "LMT"

Screw-thread lenses for Leica II, 250FF, III, 250GG, IIIa, IIIb, IIIc, IIc, Ic, IIIf, If, IIf, If, IIIg, Ig
(most are compatible with Leica M3, M4, M5, M6, M7, M8, M9, ME and Leica M Type 240 with an adaptor)

Leica 6-bit coding for Leica M lenses

Leica M lens 6-BIT CODING
From the introduction of the Leica M8 digital rangefinder all Leica M lenses were with a 6-BIT code so as to tell the camera which lens was mounted. This made it posible for the software to correct the image, and for the lens type to be read from the EXIF file.
Most Leica M lenses can be sent to Leica Camera AG and get the 6-BIT code added. Alternatively one can buy a lens coder kit from a third part and ink code the lens (the Leica Camera AG coding is engraved). Since the introduction of the Leica M9 digital rangefinder another possibility also exist in that one can manually select which lens is on the camra and so get the adjustment and info the 6-BIT code else would give the camera.

In this list the lenses that can be 6-bit coded is marked 6*

Leica Macro-Adapter M (sits between body and lens)
Came with the Leica 90mm Macro-Elmar-M lens no 11 634

Leica Elpro 52mm Close-Up Lens (sits in front of lens)
with 49 and 46mm step-up Rings. For Leica M and Leica TL lenses

Visoflex

"Visoflex" lenses were made for Leicaflex and Leicaflex SL and Leicaflex SL2 ("Visoflex" lenses with R bayonet; mainly known as Telyt-R lenses) and for Leica rangefinder cameras (Visoflex lenses with screw-threat and using a Visoflex device between the camera and the lens (see definitions in the bottom of this site)).
Can also be used for R3, R4, R6, R6.2, R7, R8, R9 (and Digilux 3 with an adapter). Some of these lenses are repeated in the R-lens section below for clarifying purposes.

Elcan-R APO (ca. 25 produced for US Military)
[by Dr. Walter Mandler]

Leica Vario-R zoom lenses

Vario R zoom lenses for R-lenses for R3, R4, R6, R6.2, R7, R8, R9 (can also be used on Digilux 3 with an adapter).
Can be used on Leicaflex, SL and SL2 unless the lens has a ROM contact .
Most are compatible with Leica M Type 240 using a R-to-M adaptor and EVF digital viewfinder for focusing

Extender-R X2 (exist as 1-cam or, 3-cam)
(for use with Leica R lenses of 50mm focal length and longer and for lens speeds from f2.0. Vignetting is to be expected with 400m and longer lenses. The 50mm f1.4 and 80mm f1.4 can also be used. Thus says the manual; however, in practical use this older 2X extender reduces quality of the picture, mainly light surfaces will 'glow' (or simply: This 2X extender will blur your shots to some degree. The newer APO-extenders below here does not).

Apo-Extender-R X2 (exists with or withour ROM contacts)
(for use with 50mm f1.4. 50mm f2.0, 60mm f2.8, 80mm f/1.4, 90mm f2.0 APO ASPH, 100mm f2.8 APO, 180mm f2.0 APO, 180mm f2.8 APO, 280mm f2.8 APO, 280mm f4.0 APO, 400mm f2.8 APO, 400mm f4.0 APO, 560mm f4.0 APO, 560mm f5.6 APO, 800mm f5.6 APO and 28-90mm f2.8-4.5, 35-70mm f4.0, 70-180mm f2.8 APO, 80-200mm f4.0 and 105-280mm f2.4).