When mounted on the 16-Mpix Panasonic GH-2 the Sigma achieves a DxOMark Lens score of 16 points which is good but not exactly class leading as we’ve come to expect from A series lenses. Nevertheless, the 8P-Mpix score isn’t bad but sharpness is inconsistent across the frame fluctuating by as much 20-percent. Distortion and vignetting are low, but that’s expected of a lens like this. Where this lens is weak is in its control of chromatic aberration. Measured at 21µm, it’s unexpectedly high and visible at every aperture in the outer 50-percent of the image field.