Erwin Puts measured his example of the lens at 0.07mm from Leica spec - which means that it would really be pushing the limits of M-KM compatibility. A 21mm f/3.4 lens lens in particular would be very sensitive to collimation, especially wide open and at a distance. So it may be a lens where Konica and Leica compatibility could diverge.
Since getting an M8, with its mercilessly flat and shallow imaging plane, I have started taking it for granted that every lens (including my Leica ones) needs recollimation to a zero deviance from Leica back focus. Recollimation, I think, is the reason why Leica wants everyone to do the 6-bit coding. For most lenses, it's meaningless. But coding and a necessary recollimation of the lens is an easy way to cover over 50 years of lenses that may or may not be within the tighter tolerances that the M8 wants. Don't want those legendary lenses to look bad.
As an aside, Konica's white papers on the 21-35mm lens indicate that when the lens is stopped down a lot, like to f/11, the 10lp/mm MTF is still 90%, but only at distances around 1.5m. At infinity and 0.8m, you are at about 30% This might explain why people report that there is "less contrast."
As a further aside, KM lenses are unusually hot in terms of contrast.
Originally Posted by rpsawin
I'm going to say it's factory as it has only been used on my analog cameras and I have done nothing to the lens. I'm curious about the recollimated reference...could you expound a bit?