Hi Lewis. Interesting observation on the difference between the FSQs.
But sorry, discussion of which types of refractors produce the least CA is out of my comfort zone (ie I have no idea
). My comment was based on the observation that stars from even the most highly respected APOs have more halo than those from reflectors - looking at figure 149 in the reference seemed to show that CA could be the culprit. That is not a criticism though, just an observation - APOs can produce very fine images. Regards Ray
ref:
http://www.telescope-optics.net/semi...o_examples.htm