... blog post:
Modern production Leica M lenses have a 6 bit code engraved into their mount which is a series of black and white 'stripes' that tell a digital M camera body which lens is mounted on it. But...
Older Leica lenses that were made in the days of film camera do not, even versions of lenses that are still in production today but were manufactured in the pre-digital days, of course, don't either though their later digital era counterparts do.
Equally, any M lens acquired from a Leica competitor like Zeiss or Voigtlander will also be uncoded.
So, can you get such lenses 6-bit coded retrospectively? Well, the answer is yes and no. Leica maintain a long list of their lenses that can be retro-coded by their service department which may be found here. As may be expected this service isn't cheap, excludes quite a few lenses which cannot be converted for technical reasons and of course they won't do this for rival makers lenses.
Which leaves us where? Well one solution for owners of non Leica M-mount lenses, or indeed those seeking a more cost friendly option for their Leica lenses, is provided by the good people at Skyllaney Opto-Mechanics.
They can add 6 bit coding to most Zeiss ZM, Voigtlander VM and Leica M lenses using their specially designed coding machine. All the work they have carried out for me so far has been excellent and I currently have three lenses (one Leica, one Voigtlander and one Zeiss as it happens) away with them being coded, as I type this.