Generally the Sigma AF 18-50mm f/2.8 EX DC macro delivered a solid performance but without being any better than the competition. The resolution results are generally very fine except at 18mm where the extreme border performance leaves something to be desired below f/5.6. Distortions as well as CAs are about in line with the rest of the gang. Typical for most dedicated APS-C lenses the vignetting could be a little better at wide-open aperture. The build quality and handling of the Sigma is fine. The Sigma offers lots of bangs for your bucks but the comparable Tamron AF 17-50mm f/2.8 SP seems to be a better alternative.