Ok, I know there awesome and great for shallow DOF, but here's my problem. When i shoot more then 1 person, there is always one out of focus. I even try shooting at F4 sometimes and to me they still come out soft. I shoot with both a 50 1.8 and 35 1.8. Usually keep torso and heads within frame (relatively close). Any tips? There's no point in fast lens if i can't make these portraits sharp. Thanks.