I got a new D5100 with 35mm 1.8, the 15-110mm (cant remember exactly). I tried to take some photos of my 4 yr old nephew but its really difficult to take photos of kids. He's always running around, and even when he's sitting in one place, his head or body moves around. It also seems my D5100 is slow to auto-focus. Seems like I press shutter half way to focus, takes a bit of time. Then even after I fully press the shutter, it seems to take awhile before it then auto-displays the photo for review. Is the D5100 particularly slow in terms of auto-focus and/or shutter? Any tips, get a different lens, use it a different way, or get a better camera? Thanks.