Sigma 24-70mm Sony mount lens review at DxOmark.

DxOmark tested the 24-70mm Sigma lens for Sony and writes:

Over image quality is good and both sharpness and uniformity are good when stopped down a little but the Sigma has high levels of chromatic aberration, particularly at the shorter focal lengths. Given the performance and the inclusion of an ultrasonic type AF motor, it’s fairly priced at $899, but still somewhat overshadowed by the better corrected and more accessibly priced Tamron.