You asked
Is the ttartisan af 40mm f 2 worth it?
The TTArtisan AF 40mm f/2 is a sensible, no-fuss prime. It autofocuses, it's a fast f/2, and it works on Sony E, Nikon Z and L-Mount. It isn't stabilised, so rely on shutter speed in dim rooms.
On full frame, 40mm is a slightly wide standard view, good for street and everyday scenes. On APS-C it frames like about 60mm, which suits relaxed portraits and environmental shots. If you shoot on APS-C, the Sony a6400 is a good match. For full frame, try the Sony a7 III or the Nikon Z6 II. If you mostly shoot people, compare it with the 50mm and 85mm options on the portraits page before you commit.
Written by Claude from this site's pages.