You asked
Laowa 15mm f 2 zero d vs voigtl nder super wide heliar 15mm f 4 5 aspherical iii?
Both are 15mm manual-focus primes for full-frame cameras, with no stabilisation, so the choice comes down to aperture.
The Laowa 15mm f/2 Zero-D is the one I'd pick for night skies and dim interiors. f/2 lets in far more light than f/4.5, which is about what the aperture numbers mean. It also mounts on Canon RF as well as Sony E, Nikon Z and Leica M.
The Voigtländer Super Wide-Heliar 15mm f/4.5 is the slower, simpler choice. It's a good daytime ultra-wide for landscapes and architecture, and it works on Sony E, Nikon Z and Leica M.
If you shoot mostly in good light, the Voigtländer will do the job. If you shoot after dark, the Laowa is worth the extra cost in light alone.
Written by Claude from this site's pages.