Disclaimer: I'm not a professional lens tester! I do this for my own interest and fun. I also just have a single exemplar of each lens. Please take this with a grain of salt.

This will show how the Voigtlander 28mm f/2 Aspherical performs on a Nikon Z7.

Sharpness in the center is excellent from f/2 on. The extreme corners are getting good at f/4, very good at f/5.6 and excellent at f/8. Below f/8 diffraction starts to set in.

Vignetting is quite high wide open but gets better when stopped a bit down.