Hi Richard,
While some of the telescopes you are considering are very high quality, they are all very small instruments by todays standards. Their small aperture limits their light gathering power and their angular resolution, which is the ability to resolve fine detail. This is the reason over 90% of the worlds best visual observers use medium to large aperture newtonians. They may own some smaller telescopes but the majority of their observing is done with a newtonian.
Quote:
Originally Posted by Decimus
I guess it all boils down a trade-off between the detail that aperture can bring from large reflectors versus the high-contrast and sharpness that can be found in a high-end refractor.
Cheers,
Richard
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There's no trade off, a modern properly constructed high quality truss dob in the 12" to 14" class will easily outperform any of the telescopes on your list, as a visual instrument in all performance criteria. It will be just as portable and even with Argo Navis and Servocat drives fitted, will cost about 1/2 of what you plan to spend on a small telescope and mount.
A 12.5"/F5 Teeter Classic with a Zambuto mirror, Argo Navis and Servocat would cost about $US 9,000 plus shipping
http://www.teeterstelescopes.com/#!classic/c1221
This telescope would blow anything on your list into the weeds as a visual instrument.
Quote:
Originally Posted by Decimus
The thing that bugs me about reflectors is the constant need for adjusting collimation (time taken away from observing) and that secondary mirror obstruction which, in some models, is substantial (50% or so in the Officina Stellare Riccardi-Honders astrographs.
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This newtonian is a specialised astrograph designed for imaging only. Newtonians properly designed for visual astronomy will have a central obstruction less than 20% which does not affect the light gathering ability and essentially gives the same Modulation Transfer Function (MTF) curves as an unobstructed telescope.
There is no constant need to collimate a high quality newtonian. You do it once when you set the telescope up, which takes less than 2 minutes and you observe for the rest of the night and invariably don't touch the collimation again for the entire night.
The difference in visual aesthetics viewing showpiece targets like Eta Carina,
M42, The Tarantula (NGC2070) and the big Globular Clusters like Omega Centauri, 47 Tuc, NGC 6752 etc etc in a 6" telescope compared to a 12.5" telescope is huge.
Cheers,
John B