I don't think that blooming is exacerbated by small wells - the idea behind that concept seems to be that when the wells fill up, the excess charge spreads across the chip to nearby pixels. But this cannot happen with ABG chips, where the excess charge is drained to earth before it gets above the potential walls of the pixels - it cannot ever get out of the pixels to spread elsewhere - so small wells/blooming is not a reason for fat stars. What happens to excess charge is illustrated here:
http://www.olympusmicro.com/primer/j...ing/index.html
non-ABG chips allow excess charge to overflow the pixels, but this charge is constrained to flow down the readout channels producing (vertical) blooming lines - it does not just spread out in all directions to produce fat stars.
Erik, I think your last post hits it on the head - fat stars are mostly caused by bad seeing. It has been terrible down here for the last two nights - huge 4 arcsecond (FWHM) blobby stars of no use to anyone. Happens to the big guys as well - the two images in the attached link are of the same bit of sky, but under vastly different seeing conditions - look familiar?
http://ftp.aao.gov.au/images/captions/aat050.html
It is also interesting that the SN has produced a huge blob - this is photo film and the blobbiness is clearly nothing to do with CCD charge overload - it is just the shape of the wings of the point spread function of the scope.
Another possible source of bloating is the chromatic aberration of refractors. Even the best APOs produce significant defocus at the extremes of the spectrum - have a look at the images from FSQ or TV NP scopes - the images can be excellent, but they show bright stars with beautiful big and smooth halos around them that I assume is from the CA affecting the luminance channel.