Conclusion: We really liked the Samsung NX 20-50mm f/3.5-5.6 for various reasons. Optically it is among the best standard zoom lenses in the mirrorless system class that we've seen so far. It is capable of delivering very sharp results across the focal length range even at max. aperture. There's only a little field curvature at 20mm. Typical for most standard zoom lenses it produces a heavy barrel distortion at the wide end. There is some pronounced vignetting at max.