You asked
Is the sigma 35mm f 2 dg contemporary good for landscape?
It's a usable landscape lens on full frame, but I wouldn't pick it first. At 35mm it gives a standard-wide view that works when you have a strong foreground, but it won't capture big skies the way a wide lens does. My landscape guide points to around 16-35mm on full frame as the classic choice.
The f/2 aperture doesn't help much here. Landscapes are usually shot between f/8 and f/11, so you'd be paying for speed you won't use. An f/4 zoom is lighter and cheaper for the same job.
If you want something wider on full frame, the Sigma 24mm f/2 DG Contemporary is on the site and gives a wider view. On APS-C, this 35mm frames like 52mm, which is too tight for most landscapes.
Written by Claude from this site's pages.