Samyang 20mm F1.8 ED AS UMC

Reviews describe good to very good central sharpness from f/1.8, with the corners lagging until about f/4 and reaching good levels by f/5.6 to f/8. Distortion is moderate and easier to correct than the 14mm's moustache pattern, and lateral colour is generally well controlled.

The main reservations concern astrophotography use wide open, where corner coma and vignetting are visible, and flare and ghosting against strong point sources. Build is solid but plain, and the lack of contacts on Sony E means no EXIF or automatic focus magnification.

Owners like the combination of a fast aperture, filter compatibility and low price, and many use it for night landscapes, events and interiors. The focus ring is described as smooth with a usable throw.

Known quirks include an infinity stop that goes past true infinity, some copy-to-copy variation in corner sharpness, and the weight and length of the E-mount version compared with native lenses such as Sony's FE 20mm F1.8 G.