Nikon Nikkor-S.C 55mm F/1.2 (USED)

This 55mm f/1.2 lens has low contrast and loads of spherical aberration and coma at f/1.2, and cleans up nicely as stopped down. If you're stopping it down, you may as well use any 50mm f/1.4 instead, and if you want high contrast at f/1.2, use the 58mm f/1.2 Noct-NIKKOR.

Today, the reason for this lens is if you want a soft-contrast effect with very little depth-of-field at f/1.2. Otherwise, at smaller apertures other lenses do what this lens does, but better, for less money.