comparing these 2 lenses are quite fair. in term of price and both non leica glass
i did some test shoot with same setting f2.8 and 1/15 seconds
without cropping i saw similiar result
here’s picture taken with Zeiss Biogon 35/2.0
and here’s taken with nokton 40/1.4
after 100% crop
here’s picture taken with Biogon 35/2.0
here’s nokton result
Conclusion :
Biogon give better detail and sharper. but for black and white i prefer nokton