You asked
Is the voigtl nder portrait heliar 75mm f 1 8 good on aps c?
Yes, it works on APS-C, with a few caveats. This is a full-frame lens, so on an APS-C body it frames like a much longer lens: about 112mm equivalent on Sony E and Nikon Z, or about 120mm on Canon RF. That's a comfortable portrait length, and f/1.8 gives roughly the depth of field of f/2.7 (Sony E, Nikon Z) or f/2.9 (Canon RF).
It's manual focus and not stabilised, so it's better for posed or slow portraits than for moving subjects. It fits APS-C bodies such as the Sony a6400 and Nikon Z50.
If you want to compare other focal lengths for people, the Portraits guide explains how each one changes the look.
Written by Claude from this site's pages.