Something that I have wondered about for quite a while - why are Schmidt-Cassegrains so popular?
They are much more expensive than Newtonians of a given aperture - and never seem to perform quite as well.
Portability is commonly cited - but when factoring in a beefy mount and tripod, they will not be as portable as a dobsonian of equivalent aperture.
The goto and tracking popular on SCTs can be had on dobsonians - and often work extremely well with features such as dual encoders.
For a comparison, take the orion xt8g and the celestron cpc 800. The dobsonian performs slightly better, has an equally good goto system, costs half as much, and is more portable.
So what gives?
Compact size. My EdgeHD 8" and 8SE mount can be packed into a space smaller than the base assembly of my 12" dob. If I go on vacation in my Prius, it is feasible to put the 8SE in the back and not loose all of my luggage room, and I have a lot more aperture and better performance on all targets than my 110mm ED refractor.
Comfortable seating position. The SCT places the eyepiece very close to the mount, and this means that from horizon to zenith, it is possible to easily reach the eyepiece without having to stand or kneel on the ground. My 8" EdgeHD 8" on my 8SE mount is the most comfortable scope to use that I own.
Better planetary performance than small APO refractors costing three times as much.. Why carry out a 4" APO for planets when it weighs as much as the EdgeHD 8", has dim images at 200x, and can't show as much detail.
Cost is reasonable. Not as cheap per inch as a Dob, but far less than a 120mm ED refractor, again, with much better performance on almost all object types.
Per inch of aperture, SCTs tend to give up to almost all other designs in terms of absolute performance, but getting a slightly bigger SCT will offset those dificienceies, and you still have all of the advantages I mentioned earlier.
Now, that being said, my primary observing scope is a 12" Go-To dob. I also own a 6" APO (Talk about expensive and requiring a big mount!!!) and a 110mm ED refractor.
My EdgeHD 8 is my least used scope, but when I need something to take on a trip, or to use for neighbors or guests, the scope I almost always turn to is the EdgeHD 8".
Heck, even Roland Christen used to have a C8... Probably still does...
Edited by Eddgie, 02 October 2014 - 02:53 PM.