For image optimization, all newer M system lenses feature a 6-bit code (indicated in black or else white dots) which allow Leica digital M cameras to recognize which lens is mounted (with as many as 64
lenses with 6-bit coding) plus retain this knowledge in the metadata of the image.
Along with utilizing this coding on every new lens Leica features a retrofitting service that allows existing M series lens owners to install the code onto each of their lenses at a charge of $136 US (95 EUROs).
New Leica rangefinder system Lenses have a code installed on the ring of the bayonet
(see the dots at the top of the image above) allowing digital Leica M cameras to identify the lens class. The coding on the lens being mounted aids the camera in optimizing image quality.
Every lens leaving the factory after July 1st, 2006 feature the new coding, though does not affect use with current Leica analog cameras including the LEICA MP, LEICA M7 along with other classic models manufactured since 1954. Current lenses as well as a great many earlier versions can be updated at the owner's cost to take advantage of the image optimization inside the M camera. These lenses are well-suited for the M digital camera even without the update code, except that the added features are not able to be utilized.
The name "6-bit coding" came about because there are six fields installed on the ring of the bayonet that are indicated in either black or white dots to symbolize a binary code number from 1 through 64. The M digital camera optically reads this information and identifies the lens based upon this binary code. In addition to the image quality improvement, the information gathered is also enter into the data of the EXIF picture file.
Because of their renowned quality, just about every Leica M lens is already perfect for use on digital. Then again, this 6-bit coding additionally takes advantage of the operation reserves in the camera's image processing system allowing the excellent image results Leica customers expect.
Many Leica lenses manufactured from 1963 to date can be retrofitted. A list of these lenses on the tables below or contact Leica Info-Service (Tel. 06442/208-111). The lone Leica lens in the present lineup that cannot be retrofitted with the 6-bit code is the
LEICA APO-TELYT-M 135 mm f/3.4. because of the 1.33 extension factor allowing it it incompatible to be used on the M digital camera
In addition to lenses currently available, even those lenses that were stopped being built quite sometime back can be retrofitted (see table below). As Leica Camera AG considers system compatibility being a vital feature, a great many lenses manufactured as far back as 1963 have the ability to be retrofitted.