buy a wedding lens for sony a57

the problem is the 85mm at f2.8  isn´t enough since I would prefer a zoom if only 2.8... and the 35mm not long enough... the 50mm f1.8 might do it... and its cheap... is it sharp wide open ? Im used to a lens like 20mm 1.7 lumix that is sharp wide open... and would fell happy if as sharp as the kit lens 18-55 at 55 (even though I think it lacks here but not less like my canon FD 50mm f1.4 at f1.4 which has good resolution but low contrast veiling haze and CA). I could get one cheap for 100 euros... maybe I will do that and use the kit lens for the training session if its sharp.

could someone post a 50mm f1.8 portrait with blurred background (at least half body if not full body).

thanks