I would say that the K 50/1.4 was "downsized" into the M 50/1.4, without any "major" optical changes (although there may have been a wee bit of "tweaking" done...).
The M lens is a new design. Different elements dimensions, curves and space between them. Boz' site for years had the same diagram for both lenses but it has been corrected last year.
I believe that the K 50/4 Macro was basically just "downsized" into the M 50/4.
Fred
Yeap. It was quite substancially downsized: shorter "internal" hood, less baffling inside the barrel. It became a "hiking" lens!
Cheers,
Andre
