You asked
Is the voigtl nder color skopar 21mm f 4 p good for landscape?
Yes, it's a sensible landscape lens. At 21mm on full frame you get the wide view landscapes need, and f/4 gives you enough depth of field when you stop down. Landscape is slow work. The scene barely moves and you'll usually be on a tripod, so the lack of autofocus and stabilisation matters much less than it would for wildlife or sport. Manual focus is fine when you can take your time and check focus on the screen.
It fits a lot of full frame Leica M bodies. Good places to start:
For why the tripod and light matter more than the body, see landscape.
Written by Claude from this site's pages.