<p>I am using this lens on a 7D with center point, AF button on and AI servo, aperture 2.8 and with basketball shots sometimes their jerseys or the ball is sharp but their face will be soft or the complete opposite problem if their face is sharp. Is this a depth of field issue shooting at 2.8 or is there something wrong with my lens? I used to shoot with a 80-200 2.8 and never had this problem. </p>