At f8, the lens is quite decent. Very sharp in the entire frame on the NEX-6. Probably less good at the corners on full frame. It's a good performer optically, but nothing spectacular. The best thing about this lens, is it's great built quality, and the very cheap price you can buy it for.
More New Condos - NEX-6 & Sigma mini-wide 28mm f2.8 @ f8. Contax mount.
Church - NEX-6 & Sigma mini-wide 28mm f2.8 @f8. Contax Mount.