The OP brought up a good question relating to focus point(s) used that I was burning to ask so many times before, but never quite understand it. How does the camera nail the focus when so many focus point is used? This is of course if the user let the camera chooses whatever is the 'optimal' focus distance within the frame, that is if the user uses 'full' auto (dumb idea anyway), I can understand that the camera will choose the proper DOF (aperture) to accommodate,
BUT what happen if the user select aperture mode? What are your thoughts?
Here is an example (taken from another user); here the lens is 16-35mm - result is that nothing in focus.