p.2 #1 · For Astro- 16-35mm iii, Sigma 14mm f/1.8 or Zies 15mm f/2.8
I have a 15-30 tamron zoom and after much study decided it was probably the best zoom available for astro work. The canon 16-35 III to me is unacceptable vignetting and poor coma. My widest lens for this work is the sigma 14mm f1.8. It needs to be stopped down to f2 for the same vignetting as the tamron and coma is better with the tamron.
In 14mm, the Rokinon SP 14mm f/2.4 is the only other one I considered. It is generally considered the best of the Rokinon 14mm lenses. Coma is better with the rokinon compared to the sigma but vignetting worse. Many consider the Rokinon ithe better astro lens and it is lot cheaper. The digital pictures and others lean towards the sigma.
p.2 #3 · For Astro- 16-35mm iii, Sigma 14mm f/1.8 or Zies 15mm f/2.8
Flowernut echoes my observations. Tamron 15-30 or Rokinon 14mm.
Other good choices as well as mentioned.
Scott Stoness really likes the fast Zeiss wide primes.
