Quote:
Originally Posted by toyos
I put 4.5" off-axis aperture stops on a 12" dob and a 12" SCT (I know a 12" f/10 SCT with a mask is not ideal) and compared them against 4" & 5" Apo's. Even the cheap 127mm Chinese Apo blew both reflectors away by far when used with the 4.5" aperture stops.
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What you fail to understand is that you continue to compare refractors against poor quality newtonians, or newtonians that are not properly optimised and or set up. It is possible to make a horrible mess of a newtonian. It is a lot harder to make a horrible mess with a refractor.
In this thread
http://www.iceinspace.com.au/forum/s...ad.php?t=31267
You actually asked "what's wrong with my newtonian". I told you what was likely wrong with it. I also told you how to fix it. You didn't want to listen and have now formed an opinion based on a very small low end sample of newtonians. Comparing a GSO dob/newt to a premium newt is like comparing a Lada to a Lexus. You fail to realise you were only driving a Lada and a broken one at that.
I happily concede that a refractor will always have greater contrast when compared to a newtonian, but when compared to a high grade properly optimised newtonian, there isn't much in it. No where near the difference you are claiming. A properly set up high grade 10" newt will in fact smash any 6" APO and by quite a margin on anything, inluding lunar/planetary. A medium quality poorly setup 10" newtonian probably won't equal a 6" APO for lunar/planetary.
A 12" SCT isn't even worth comparing against a good newtonian or a refractor. They are a convenience scope that does a fair job of everything and a good job of nothing. Further, they take about 3 years to cool down properly to deliver 1/2 decent views and they only ever get to 1/2 decent views.
Cheers,
John B