You tap on the screen on what you want the focus on. . . literally a split second and it focuses where you want it to. Otherwise it multi focuses on the faces.
Like my Galaxy S III ... from 2 1/2 years ago.
I recently had an iPhone 5 for a couple of months ... nice piece of hardware ... apps work well ... iTunes is a pain in the rump ... people who rant and rave and get personally emotional about the supposed superiority of one platform over the other have their heads up their butts.