Any spot size that is smaller than the diffraction disc is meaningless, even with perfect seeing, since it is using ray optics and ignoring the wave nature of light. I don't have the actual data, but reporting a spot size 20x smaller than some quality telescope is probably reporting a spot size smaller than the diffraction disc, so in real life the pic you get from it would be limited by the wave nature of light in perfect seeing (never going to happen) or, more realistically, by the seeing conditions.
Geoff
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