This image shows the result of adjusting the primary mirror to center the
dim outer ring around the bright inner rings. The most obvious (and surprising)
thing here is that the width of the dim outer ring is no longer consistent; it is
much thinner at the bottom than at the top. It seemed as though I had a choice: I
could either get the rings centered, or I could have the width of the outer ring
consistent, but I could not have both at the same time. Notice also that the central
shadow is now slightly off-center within the bright rings. This began an iterative
series of small adjustments to the secondary and the primary mirrors. See the result
in image #3.