When photographing families...or even couples, I sometimes find that I get one person in focus but the others will be slightly soft focused. It isn't terrible...slight enough that I can't see it in the viewfinder. But still...I want the subjects to be sharp. I typically shoot portraits with a 50mm/1.8 on my D200 most times stopped down a bit for multiple subject shots particularly to help with this issue. Would a longer focal length help me? What other tips do you have that will help me with ensuring focus for multiple subjects?