Ditch the ‘kit’: Sigma 17-70mm f/2.8-4 DC Macro OS HSM ‘C’ review

I just came back from my holiday where I was shooting exclusively with this lens. I actually bought it for this holiday. Now, after converting from RAW and analysing several K of photos, I can confirm that 17mm is a bit more problematic than it was with original 17-70. However, I can clearly see field curvature effects here. Many shots are softer in the corners near infinity, but quite sharp in those corners with objects in the mid range. Soon, I found out that it gives better corner sharpness when I’d choose focus at infinity and stop down to f5.6 – f8 (I was accustomed to focus on closer objects at this focal length). Will try USB dock to compensate for this. Shooting close-up and mid-range objects, sharpness is more than adequate @17mm. The rest of the range is more straight forward to get consistently good results. Overall – great lens, super versatile, much better that the original 17-70 in every regard (even 17mm is better overall, IMO)

Source Article from http://www.dpreview.com/news/2013/08/05/just-posted-sigma-17-70mm-f-2-8-4-dc-macro-os-hsm-c-lens-review