You asked
Is the samyang af 14mm f 2 8 good for landscape?
Yes, the Samyang AF 14mm f/2.8 is a good fit for landscapes. At 14mm on full frame it takes in big skies and strong foregrounds, which is what the Landscape page calls the classic job for a wide lens, and it's wider than the 16-35mm zooms it describes.
You won't need the f/2.8 aperture much. Landscape work usually happens between f/8 and f/11, and the page notes that f/4 zooms are lighter and cheaper for this reason. The lens isn't stabilised, so a tripod helps in dim light.
It fits full-frame bodies like the Sony a7R V and the Canon EOS R5, where the high resolution suits landscape detail.
Written by Claude from this site's pages.