You asked

Sigma 16 28mm f 2 8 dg dn contemporary vs sony fe 16 25mm f 2 8 g?

Here is what the site says about that.

From Sigma 16-28mm f/2.8 DG DN Contemporary: Sigma 16-28mm f/2.8 DG DN Contemporary: A zoom lens by Sigma for Full frame cameras, 16-28mm f/2.8. Specs - Maker: Sigma - Focal length: 16-28mm (zoom) - Maximum aperture: f/2.8 - Made for: Full frame sensors - Mounts: Sony E, L-Mount - Stabilised: no - Autofocus: yes What it frames like - On full frame (Sony E, L-Mount): as marked, 16-28mm. - On APS-C (Sony E, L-Mount): like 24-42mm on full frame; f/2.8 gives about the ...

From Sony FE 16-25mm f/2.8 G: Sony FE 16-25mm f/2.8 G: A zoom lens by Sony for Full frame cameras, 16-25mm f/2.8. Specs - Maker: Sony - Focal length: 16-25mm (zoom) - Maximum aperture: f/2.8 - Made for: Full frame sensors - Mounts: Sony E - Stabilised: no - Autofocus: yes What it frames like - On full frame (Sony E): as marked, 16-25mm. - On APS-C (Sony E): like 24-38mm on full frame; f/2.8 gives about the depth of field ...

Quoted from this site's pages.

From these pages