You asked
Best wide angle lens for the sony a9 iii?
For the Sony a9 III, my pick for a do-it-all wide angle is the Sony FE 16-35mm f/2.8 GM II. A constant f/2.8 keeps the exposure steady across the zoom, which matters when you're shooting fast.
If you want something lighter and brighter, the Sony FE 14mm f/1.8 GM gives you a wide view with more light to work with. For a cheaper prime at a similar focal length, look at the Sony FE 16mm f/1.8 G.
The a9 III is full frame, so these lenses frame as marked. If you're unsure how much a fast aperture matters to you, the lenses guide on aperture explains the trade-off.
Written by Claude from this site's pages.