You asked
Best wide angle lens for the sony nex 5t?
For most people on a NEX-5T, I'd pick the Sigma 10-18mm f/2.8 DC DN Contemporary. It runs from 10mm to 18mm, which is roughly 15-27mm on full frame, and it stays at f/2.8 across the whole zoom. That constant aperture matters: cheaper zooms get darker as you widen or zoom, and this one doesn't. Good for interiors, streets and landscapes in dim light.
If you want the widest view possible, go for the Laowa 8-16mm f/3.5-5 Zoom CF, about 12-24mm on full frame. It opens up less, so it suits daylight better.
For a fisheye look, the Sony FE 8-14mm f/3.5 Fisheye G is the one to consider.
For a bit more on how aperture affects light and blur, see the Lenses guide.
Written by Claude from this site's pages.