Sigma 18-200mm F3.5-6.3 DC Macro OS HSM C Canon mount lens review: Worthy upgrade?By Kevin Carter - Friday March 28 2014 Lens Review
Sigma 18-200mm F3.5-6.3 DC Macro OS HSM C performance
A DxOMark lens score of 12 points is above average in this class. It has slightly higher sharpness than expected at this level (not just a high peak sharpness equating to 9P-Mpix) Best of all perhaps, sharpness at 200mm is good at the initial aperture, at least in the center of the field.
There’s some softness at the edges but it’s remarkable at this price. Vignetting and chromatic aberration are very well controlled and distortion is also kept to reasonably low levels at the wider end. Change focal length though and the barrel distortion changes quite abruptly to pincushion and is quite noticeable at 35mm to 50mm, but less so at longer focal lengths.