This lens is 55mm f/1.0~f/11 , was manufactory in Japan by Kowa. Lens was rework on Panasonic Lumix G1 GF1 GH1 or Olympus E-P1 E-P2, Now I also rework on Sony NEX-3 Nex-5. After rework image little large than 50mm, I was use smaller focus Schneider and angenieux 25mm/0.95, they all have 4 dark corners. Lens focusing from 3ft to infinity. ...чё он там переделывал я не врубился