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Originally Posted by Merlin66
the feeling seems to be that the image saturation will cause the 7% residual light in the "1st Airy ring" to contribute to the image size.
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And that's exactly the case.
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This doesn't seem to match....
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With what exactly? The size of the Airy disk and the spacing of its rings depend on your aperture and focal length (and CCD resolution of course).
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(BTW with the Hubble...if there's no atmospherics to "smear" the Airy disk --why do brighter stars still look larger?? )
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That's because Airy disks have nothing whatsoever to do with atmospherics- diffraction is the main cause of your stars not being neat points! All telescopes will necessarily have to diffract the light, even the Hubble.
EDIT: I think your analogy is flawed as a laser beam is not a focused beam of light. All photons travel in parallel and have not been diffracted yet, thus showing no Airy disk on the paper. Also you seem to assume there is just one (or two) rings around the primary Airy disk. In fact there are many and they extend for the full surface area of the aperture.