Take a look at these--all images were shot at f. 1.8| 1/100th sec| 800 ISO. All were set to focus on the middle point, which I aligned with the lamb's eye. In each case, I got the red "locked" focus point.
Here's the 6 Foot shot cropped closer:
The focus is significantly less sharp at 6 feet compared to at 2. Is this normal for using auto-focus?