Rick,
I just now discovered your engaging discussion of the K version of the early generation Nikkor 50mm 1.4s. Your observations bring back memories; the 50 1.4 (S C variant) was central to my introductory years (1970s). As you indicate, center frame and edge performance improves markedly stopped down, much like Nikkor wide angles. Just recently, a backyard comparison between an AI-converted 50 1.4 S to a 50 1.4 AIS shows across-the board improvement, particularly with respect to color fringing at the transition points between deep shadows and bright highlights. Yet, the earlier 50mm seems to have smoother bokeh. I find this to also be the case comparing early vintage and AIS 105s.
