There are many incredible Newtonian images around. The conical mirror is easy to make so its easy for manufacturers to get really high accuracy with modest manufacturing.
RC optics are hard to make hence the high cost. Their advantage though seems to be long focal length and no coma. They are also relatively compact and the camera is at the end not on the side of the tube.
The disadvantage of a Newt as I see it is they are very long for their focal length and the camera has to be mounted on the side opening the door to flexure issues, and length of backfocus for all the accessories used today.
The side mounted camera and short backfocus problems were highlighted with the ASA scopes where flexure and focus slop were a problem (apart from the mirror mount etc). Tubes are only so strong even carbon fibre.
But when the ASAs got it right they were awesome in the 1200mm focal length band.
RCs and similar designs though seem to totally dominate the long focal length/galaxy type imaging scope area. Not so great for widerfield though.
I see A&M has a compromise RC which is F5 and wide field yet an RC 360mm aperture I think it is. It probably is a simple matter to extend the focal length if you wanted to do galaxies.
Ceravolo astrograph is an attempt to service both widefield and long focal length and seems to do very well. But its very expensive.
Planewave CDK seems to the be the current market leader in long focal length compound scopes.
Someone mentioned wanting to see CDK20 images. There is one good one of the Jellyfish neb on their site but here are a few from Bob Fera who is a great imager using a CDK17:
http://www.feraphotography.com/CDK17/HH.html
Click through his site to see more examples. Impressive. Looks more like an RCOS 20 inch result.
Orion Optics UK, A&M, RCOS, Ceravolo, Starizona Hyperion, Deep Sky Instruments are other hot instrument makers. It is quite competitive these days in this band.
Greg.
