And the centerpoint will probably change depending on how close or far the object your photographing is. This is the majority of the reason that cheap cameras tell you that the subject should be at least 4 feet away. Any closer and you run the risk of not photographing the right thing at all. Most have enough depth of field to get a reasonably crisp picture well closer than that. Which is why I prefer to use the screen, when forced to use a digital camera.