The 50mm f2 AI is a very good lens, read the Nikon Thousand and One Nights post about it for more detail on its 'interesting' imaging traits. I use the slightly older H.C. version and while I am pretty convinced that they are the same optical formula I just seem to like the H.C over the 2 other Ai and K series. The color rendition is something that is seldom mentioned, it has really fantastic color. While it is very good close up, quite sharp, it does have a bit more distortion so I am either careful about close in portraits or I use the obviously better 1.8 Ai longnose, which even as the Nikon designer says has much lower distortion. I've modified my 50mm H.C f2 to have 1/3 F-stops up to F4, some of those in between F-stops have some pretty compelling bokeh. Wide open has its challenges.