Thanks for the information, Kevin. I suspected that the Ultron is an undervalued lens, and this is why I got it. I am very used to my Rigid Summicron, so I now know what to expect from the Ultron. It is not in M or LTM, and an adapter or two must be used with the lens. Most likely, the Nokton and the Ultron have similar bokeh and performance at apertures 4.0 and up.