"Hither" sets the point at which anything closer to the camera is invisible. To see it in action sight the camera up an arm from the finger tip and move toward the fingertip slowly. At some point, the tip will disappear and you will see "inside" the finger. Reduce Hither, and the fingertip will reappear. Technically, you could do the camera from the head's POV by putting the camera behind the head and then setting Hither to make the entire head invisible. That would have parallax problems with objects close to the head, though.