You asked
Samyang af 16mm f 2 8 p fe vs sony fe 16mm f 1 8 g?
Both are 16mm primes for full-frame Sony E cameras, and neither has stabilisation. The difference is mainly aperture and close focusing.
The Sony FE 16mm f/1.8 G is the one I'd pick for dim light, such as interiors, night streets, or astro. f/1.8 gathers far more light than f/2.8. It also takes ordinary screw-in filters, which matters if you shoot landscapes with polarisers or grads.
The Samyang AF 16mm f/2.8 P FE is the choice if you want to get very close to a foreground subject for dramatic ultra-wide shots. It's a small lens that focuses very close, and f/2.8 is plenty for daylight.
Both fit the same full-frame and APS-C bodies, so the camera won't decide it for you. For more on wide framing, see landscape.
Written by Claude from this site's pages.