I found this legacy Konica lens for 5.- CHF (~5 USD) at a local second hand store. According to buhla.de "some magazines would praise it as one of the sharpest lenses ever built by anyone". As soon as my Konica AR to NEX adapter arrives, I will give it a shot.
The picture was taken with the Sony NEX-7 and the Sony 50mm f1.8, using my recently build, dirty-cheap product photography setup (a white sheet of paper and two opaque plastic boxes with 21 watt energy saving lamps).
Edit: First picture taken is online