Sigma 24-70mm f/2.8 DG OS HSM Art

Users will find that centre and corner sharpness improves considerably by stopping the lens down from f/2.8. Centre sharpness at all focal lengths peaks between f/4-f/ 5.6, with the best edge-toedge sharpness being located between f/ 5.6-f/8. Corner sharpness never reaches the same level as centre sharpness, and our results tell us that it delivers sharper results into the corners at wider focal lengths than it does at the far end of the zoom.