I'm pretty new to using a steadicam and I'll be using it for family vacations or just to record around our backyard/playground/family time. For my camera I use a Nikon D5200 and I currently have an 18-200 VR lens and a 50mm lens. What would you personally use (other than what I have, still, zoom, or cine lens) to film a 2 year old running around the backyard or playground? I find it hard to keep focus with these lenses while I'm chasing after her. Any tips for keeping focus, too, is great appreciated. I did more still shots when she was little but now that she is on the move I would like to keep up.