looking at the crop trev, it looks as if you have applied some heavy noise control, its so hard to explain to you what i see on this end, though i don't believe that its your focal length that is causing your issue, looking at Grahames gso rc10 which is practically the same scope the images come out clear as anything, furthering to this the stars seem to have a large soft halo around them which i havn't seen in other RC8's, sure they have that nice glow but not a soft fuzzy look.
http://paulhaese.net/ThorsHelmetHaRGB.html
just for example, yes i know there's a lot more exposure time but that doesn't change the soft/sharp look.
Im sorry if you think im harsh, but i believe that nearly anybody who posts images up on this site are looking for ways to make their images better, if it was to do with colours, well that is totally up to the user to decide as its personal pref, but things that everybody can comment on is the mechanics, focus, flattening, guiding, ect ect.