Up until now, the 6-bit coding has not been available for the Leica APO-Telyt-M 135mm f/3.4 ASPH. All previously sold lenses were delivered without this coding and there was no option to have this done at a later date. However, Leica just announced that this is finally available after January 15, 2013.
If the lens was purchased AFTER September 1, 2006, Leica will charge $200 for the coding. If the lens was purchased BEFORE September 1, 2006 the cost of coding will be $300. Any lens purchased after September 1, 2012 will be coded free of charge.
In addition to the 6-bit coding, Leica is also offering the ability to purchase an 18 month certified pre-owned warranty for $50. The certification is valid for 18 months from the time of conversion and includes all lens functions tested on factory equipment and complete cleaning of the external surfaces of the lens.
According to Leica, the 6-bit coding has the following advantages:
All Leica M-lenses leaving the factory are equipped with a code on the bayonet ring which enables the digital Leica M camera to recognise the lens type. The information on the lens that is being used helps the camera to optimise image quality. Lenses in the current range as well as many earlier models can be retrofitted (at the cost of the owner) to benefit from the image optimisation in the camera. The lenses are compatible with the digital M camera even without retrofitting, except that the additional features cannot be used.
The lens coding is called ‘6-bit coding‘ because six fields in the bayonet ring are marked in black or white to represent a number from 1 to 64 in binary code. The digital M camera reads this information optically and can identify the lens on the basis of this code. Apart from the improvement in image quality, this information is also written into the EXIF image file.
Many of the lenses made from 1963 onwards can be converted. A list of such models is available in the PDF document "M Lens Coding List". Please ask either your authorised Leica dealer or Customer Care in Solms to perform the update. The latter will be happy to inform you on this subject. Customer Care is available at the phone number +49 (0)6442 208-189.