SurefireI had the Sigma 35 F1.4. Image quality was excellent all the way to the corners. Its hard to compare the 2 lens since the Sony starts at 2.8 and yes at 2.8 and beyond this lens is also excellent. So why did I return the Sigma?, well it weights too much and is not fun to carry around. Since I picked up a Sony 24/1.4 In January the Sony 35/2.8 works well in my kit when I need it. And the Sony 24/1.4 is much lighter at 15.7oz vs 1.47 lbs for the sigma.