Sigma 50-500 mm f4.5-6.3 APO DG OS HSM Canon mount lens review: Modest price, good performanceBy Kevin Carter - Tuesday November 05 2013 Lens Review
With an overall DxOMark lens score of 17 points, the Sigma lens behaves very well given the large zoom range and long focal lengths involved. It has a surprisingly high sharpness score of 14P-Mpix, though like many models it’s sharper at the shorter end. Sharpness is somewhat inconsistent across the zoom range but, fortunately, it’s still good at the longer focal lengths. Distortion and vignetting are both low, as expected in a lens like this, while the low-dispersion glass has kept chromatic aberration down to reasonable levels.