You asked
Is the voigtl nder nokton 17 5mm f 0 95 aspherical sharp wide open?
I don't have anything on this site that tells you how sharp the Voigtländer Nokton 17.5mm f/0.95 Aspherical is wide open, so I won't guess. What I can tell you is that it's a manual-focus prime for Micro Four Thirds. On that sensor it frames roughly like a 35mm lens on full frame, and f/0.9 gives about the depth of field of f/1.9 there. You can see the full spec and the list of compatible bodies on its lens page.
If you're buying it for shallow depth of field, the portraits guide explains how wide apertures behave in practice, including why stopping down slightly can help. For a sharpness comparison, check independent test results before you buy.
Written by Claude from this site's pages.