You asked
Samyang af 24 70mm f 2 8 fe vs sigma 24 70mm f 2 8 dg dn art?
Both lenses cover 24-70mm at f/2.8 for full frame, with autofocus and no stabilisation, so the choice comes down to mounts and which camera you own. The Samyang AF 24-70mm f/2.8 FE is made for Sony E only. The Sigma 24-70mm f/2.8 DG DN Art fits Sony E and L-Mount, so it's the safer pick if you might switch systems. It's also the first version, and Sigma replaced it with the DG DN II Art in 2024, so check that page before you buy.
If you shoot Sony E, the Samyang does the same job. Both keep a constant f/2.8 across the zoom, which my aperture notes explain. For more on third-party lenses, see the third-party section.
Written by Claude from this site's pages.