I know this is telling me something good but can someone explain what it means? I get lost in the words. “There are two reasons: first, in the common range of telescope focal rations (i.e. from f/4 to f/16) the size of the diffraction disk is considerably smaller than the individual photosites on most CCDs; and seconed, the seeing disk and tracking errors are considerably larger than the diffraction disk.” So what is that telling me, "the diffraction disk is considerably smaller than the individual photosites"? How is that good? Aslo, "the seeing disk and tracking errors are considerably larger than the diffraction disk.” I figure it means that you can't see the tracking errors but how? Also I keep reading about star image blooming. Does anyone have an example of that? Thanks Jim