An excellent wild zoom for its price, center sharpness is very good but the corner is a little bit soft. Just like the 12-24mm, this lens hardly flares; however, the chromatic aberration problem of 12-24mm is not presented with this lens. Light fall-off is visible if not stopped down a little bit (beyond f5.6) while the same non-slim B+W filter is used on it. Distortion is visible over the whole focal length. In addition it has 7 rounded diaphragm blades, just like the 12-24mm. On a Nikon DSLR it's 27-52.5mm and it weighs only 370g, so it's ideal for travel. On the full frame camera and focus to infinity, softness at extreme corners is observed, after f5.6 it's not too serious except for 35mmm.