If sharpness wide open is your priority I recommend the rollei planar 50mm f1.8. It is very sharp and not too expensive, although the rollei to m4/3 adapter is a little more expensive than the others.Which one of these lenses is sharpest when fully open aperture? most compact? fastest and easy to use focusing ring?
Nikon Nikkor 50mm f1.8 Ai or Ai-S
Pentax Super Takumar 50mm 1.4
Canon nFD 50mm 1.4
Konica Hexanon 50mm 1.7