You asked
Is the leica noctilux m 75mm f 1 25 asph sharp wide open?
I don't have sharpness test results for the Leica Noctilux-M 75mm on this site, so I can't tell you how sharp it is wide open. What the lens page does cover is that it's a manual-focus prime for full frame Leica M bodies, with no stabilisation.
Wide open, depth of field is very thin, so getting focus exactly right will matter more than anything else. The aperture guide explains what a wide f-number does to light and blur, and Portraits covers how thin focus can get at f/1.4 and wider. For a sharpness verdict, check independent lens reviews before you buy.
Written by Claude from this site's pages.