I could never get my 50 1.8 to behave nicely with focal either, I think it has something to do with the non usm motor. Luckily it's pretty sharp as is and for $100 it's tough to beat. Some softness wide open is normal, are you still getting the "dreamy" look at f2.8? If so than maybe a bad copy and just return it if you can or forgo focal and Afma the old fashioned way with a lens align tool.