Opticallimits

More like 5* ;-)

And no, it's not a Canon lens.

Sigma?

Sony G

Someone got their hand on the Fuji 16-80mm early? Just kidding. Maybe the Tamron 35mm f1.4? Or the 35-150mm f2.8-4?

Sigma 105/1.4?

Oly 45mm 1.2?

Dulens? Yasuhara? Meike? Voigtländer? Lensbaby?

No matter of the brand, it should be either 50 mm or 35 mm and strictly manual focus without any electrickery inside.

Or maybe Klaus has finally succumbed to the temptation and gotten the Voigtländer 110mm.

Tamron 35mm f1.4?

Tamron 35mmf1.4 here too