Sigma 18-35mm F1.8 DC HSM A Nikon mount lens review: Unrivalled Standard ZoomBy Kevin Carter - Tuesday November 19 2013 Lens Review
On the 24-Mpix D7100, a camera noted for its high resolving power, the Sigma achieves a very high 17P-Mpix score only matched by the current Sigma 50-150mm f2.8 model and is very sharp centrally at maximum aperture at all focal lengths.
Not only that, but uniformity of sharpness is very good at full aperture, deviating by less than 7% percent across the frame. Peak performance is at f5.6 with edge-to-edge sharpness throughout the zoom range.
Distortion can be a problem in zooms like this but while some barrel distortion is noticeable at 18mm and slight pincushion can be seen at the longer end it’s quite mild.
Both vignetting and chromatic aberration are also low, though, surprisingly, CA is more conspicuous in the corners at 24mm than at 18mm. Also worth mentioning is the excellent, mostly consistent 2TStop transmission measurement at full-aperture.