If just 2.8 aperture and autofocus would not ...

Wanted to move in the lower zoom range high up with this lens, unfortunately, was sorely disappointed, so that the object unfortunately went back immediately. Have it tested long against an entry Sigma 18-200mm telephoto (f3.5-f5.6) ... overall, the Sigma 17-50 in the intermediate focal length and aperture range (F5-F11) could indeed against the said object of comparison in terms of focus and clarity of the images prevail (though to my amazement with little distance); However, the quality of F2.8 was extremely poor and most of all I achieved with the autofocus not a single sharp photo (from> 50 tested); also in the middle aperture range, the autofocus extremely disappointed, also it was not possible in Live View mode to use the autofocus at all ... probably it should simply not be. Teste truly the Sony SAL 1650 and hope that the Sync with my Alpha 580 works better there.