You asked
Is the sigma 12mm f 1 4 dc contemporary good for landscape?
The Sigma 12mm f/1.4 DC Contemporary is a good wide choice for landscapes on APS-C. On a Fujifilm X or Sony E body it frames like an 18mm lens on full frame, which is wide enough for big scenes. The f/1.4 speed matters less here, because landscape work usually means stopping down for depth. It isn't stabilised, so a tripod is worth bringing, as the landscape page explains.
If you're choosing a body to pair with it, I'd start with the Fujifilm X-T5 or the Canon EOS R5 Mark II. For a full-frame body, try the Sony a7R V, which the lens also fits in APS-C crop mode.
Written by Claude from this site's pages.