Quote:
Originally Posted by ausastronomer
Les has given you some great advice. If you can find a Suchting mirror buy it, regardless of the coating. Just use the coating quality as a price bargaining point. Mark's mirrors are all exceptional and well worth getting re coated. The mass produced Taiwanese / Chinese mirrors from GSO and Synta are generally pretty decent. I have looked through well over 50 of these scopes over the years and I would assess them as follows. Of the 50 plus scopes I have looked through I have seen 2 ashtrays that I wouldn't waste my time looking through. About 1 out of 10 I would rate as ordinary, but it's going to have to do. About 6 out of 10 are pretty decent and happy to use them, 2 out of 10 are very good and 1 out of 10 are exceptionally good. I have a 10" F5 GSO dob that I have had for about 18 years that I leave at a friends rural property so I can use it when I go there without having to transport a scope. I also have a premium 10"/F5.3 SDM with Suching mirror, which is as good as it gets for a 10" scope. I got very lucky with the 10" GSO. It has an exceptional mirror for a mass produced scope. David Collis Bird bench tested it for me many years ago and his only comment was "I don't know how they can make a mirror this good for that price". Is it as good as my Suchting mirror ? Not quite, it's not quite as smooth so contrast under really good skies is slightly down, it has a touch more scatter and it is thicker and takes longer to cool. However, it takes good conditions with dark steady skies, good eyepieces and an experienced observer to pick a difference. The defining factor however is that 1 in 10 mass produced mirrors are this good and all of Mark's perform at the same level.
Cheers,
John B
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Thanks John for your valuable input .
I already have a AOS 10" in an old truss dob that probably is a Suching mirror , it's performance was outstanding from what I remember many years ago .
I'll pull the mirror out & maybe sell it with the cell and other parts .
It deserves to see again !
Very interesting about the Horse head & individual red light sensitivities .
No wonder I could never find it back in the 70s with my 8" f/7
Have Fun
Bobby .