Vivek . , Aug 02, 2007; 06:51 a.m.
Thank you for your brilliant post of your analysis, Dr. Caldwell!
I think the Leica M8 has one of the thinnest sensor cover plates as you note.
I wondered about it when I use a Canon 50/0.95 TV lens on my Epson R-D1s (almost always wide open) if there are anything else induced other than strictly what the lens projects.
Also, from the Nikon's bodies and lenses, oddly, the old 18-70 kit zoom (issued with D70, cover glass 1mm plus another ~0.1 to 0.2 mm thick BG/AA filter) appears to perform poorly on a D40x (cover glass is > twice as thicker and has more efficient coatings to eliminate IR and UV)while its own kit lens (18-55 AF-D g, etc version II) does much better on the D40x. Both are 'DX' lenses 'designed for digital.
Can't a software fix be applied to correct astigmatism?