[alpal]

Originally Posted by Camelopardalis

Thanks Greg. What I'm struggling with is why they'd deal with thermals/layers better if the contrast and resolution is better

http://www.garyseronik.com/?q=node/55

Though refractors and reflectors both have thermal issues, those of the refractor tend to be mild and short lived because the objective lens is exposed to the night air. The primary mirror of a Newtonian reflector, however, is shielded by a long tube that inhibits cooldown.