Samyang's fast ultra-wide for Sony — the 20mm f/1.8 manual prime for astrophotography.
The Samyang 20mm f/1.8 ED AS UMC for Sony E is a fast manual ultra-wide prime designed for astrophotography and low-light wide-angle work. At f/1.8 and 20mm, it provides useful speed at the ultra-wide angle. ED and aspherical elements control aberrations. UMC coatings reduce flare. Also sold as Rokinon. A budget astro ultra-wide.
Good optical quality for the specification. Sharpness respectable from f/1.8. ED element controls chromatic aberration. The f/1.8 at 20mm gathers meaningful light for Milky Way photography. UMC coatings reduce flare. Coma control reasonable for astrophotography. Build quality solid metal. A proven manual astro prime design available across many mounts.
Sony E mount, manual focus only. Filter thread 77mm. Weight approximately 488 grams. No electronics. The Sony mount benefits from IBIS for handheld wide-angle. The 77mm filter thread enables standard filters. The same optical design is available in virtually every camera mount. Good for astrophotography on Sony full-frame.
Available at budget prices. Check smooth focus and clean optics. A solid budget astrophotography prime for Sony. The f/1.8 at 20mm provides useful astro capability. Benefits from Sony IBIS for handheld use. The Sigma 20mm f/1.4 Art offers more speed and AF at higher cost. Good value for dedicated astro work.