I've been doing some more testing on the D-90 and 10.5 fisheye combination and my results are slightly different from what the Camera Settings page suggests. (Assuming the D-80 figures remain the same for the newer camera, which I believe they do.) Instead of 48 - 86, I'm showing best results with 47 - 83. Is this enough of a difference to matter or should I just shut up and go take some pictures?
Interestingly, when I tried the "Sawtooth" test, as recommended by John H. and others, the result was slightly different from what the "aim the camera straight down and center the target in the viewfinder" method gave me. Is that because of a slight de-centering of the viewfinder in a camera that's not set up for 100% view?