If you need closer focus capability, a lens with a shorter focal length (wider field of view) is more important than just a lower f-number
F/1.0 would have better ability at low light then say a 1.6 or 2.0. Would want to find a camera with a good mm like 2.8 to 4mm at f/1 would have in most cases a better closer distance view and slightly blurry background then say a 6mm or 12mm lens with a 1.6f-stop. So to be clear, no matter the f/stop the 12mm lens can see better farther away, then a 2.8mm that would have a better closer range view again no matter the fstop of the camera lens..