With 6-bit code on the bayonet ring
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.