Test: Einzeltest: Sigma AF 20mm f/1.8 EX DG RF (FX)
Zitat: Just like its slightly longer sister lenses, the Sigma AF 20mm f/1.8 EX DG leaves us with mixed impressions. The center resolution of the lens is very good to excellent, while the borders and corners disappoint especially at large apertures. Vignetting is very pronounced wide open. CAs and distortion are well under control, especially for such a wide lens.
The bokeh is somewhat nervous at large apertures, but improves considerably when stopped down a little.
Unlike its sister lenses, the EX does not feature a moving inner lens tube and consequently no wobbling. In fact, the lens is very solid and the build quality nothing to complain about.
In summary, the verdict remains the same for all three lenses: not an attractive choice for landscape shooters, but because of the very short minimum focus distance it´s an interesting lens to shoot close-ups with wide perspectives. The maximum magnification is lower than with the two longer lenses of the trio, but due to the short focal length the perspective can be more dramatic.