Lets take a look at what the AF sensor actually sees when we point the camera towards an object and activate the
autofocus. The example we will use here is of a female moutaineer in front of her ´"focus target", as imaged through
the view finder.



 

The animation below in turn shows AF sensor itself,  the part images projected by each SIR lens onto the
corrensponding group of pixel arrays, and finally the part of the projection captured by each of these pixel arrays.