12.5 f/5 R.F Royce vs 12.5 f/5 Discovery Primary M

I would love to get some feedback on mirror quality and any comparison you can provide on these two mirrors head to head. I'm at a point in my project where I need to purchase a mirror. I'm building an open truss GEM mounted f/5 Newtonian.

Thanks Paul

Can't speak about the Royce but I'll throw in my 2 cents on Discovery--I had an 8" f/5 that was a little gem, and a 10" f/5.6 that was a dog. Ok the 10" was a pretty old mirror and maybe they improved their QC, but...

To me, a primary reason for building my own scopes was to take the savings and put it into the best optics I could afford. At $1350 or so, Royce, Stevens and Swayze all represent good buys on a 12.5" f/5, albeit a good $500 over the discovery. I imagine Zambuto is yet somewhat more. I suggest you have a look at these other two guys as well as Royce:
http://home.europa.com/~swayze/pricelist/pricelist.html
http://www.stevensoptical.com/mirrors.htm

Good luck!
George

Paul Neesam said:

I would love to get some feedback on mirror quality and any comparison you can provide on these two mirrors head to head. I'm at a point in my project where I need to purchase a mirror. I'm building an open truss GEM mounted f/5 Newtonian.

Thanks Paul

Hi Paul!

R F Royce is among the very elite mirror makers. His conical mirrors are supposed to cool quickly and only require a very simple mirror cell. I own a 12.5 f5 conical from Royce. Unfortunately the scope kit provider that I paid is 18 months behind on my delivery, so I can't tell you how wonderful it is at the eyepiece. But Royce is where I put my money, and I do not believe that you could go wrong with a Royce mirror.

That said, Discovery makes very good mirrors (full thickness), and there have been some posts suggesting that their figure is consistently good (some have been taken to experts to be refigured, and ended up only being polished to a finer level). You wouldn't really go wrong with a Discovery.

Carl Zambuto is the buzz-name in fine mirrors. I wouldn't suggest that anybody makes a finer mirror. But, I remain unconvinced that Zambuto mirrors are really visibly superior to the other elite mirror makers (Swayze, Spooner, Raycraft, Royce, and a number of others). Zambuto mirros are lightweight and require a sophisitcated cell for support. Obviously, you wouldn't go wrong with a Zambuto, unless you tried to put it in an inadequate cell (and that would not be Carl's fault).

The big issue will not be the actual views but your own worries about the views that "Could have been."

Lorne Johnson

Check out Lightholder Optics. I have a 10" and 16" from him. Both are excellent.

For what it's worth, I believe there is some question as to whether or not Terry Ostahowski is still making all or any of Discovery's mirrors. I spoke with him a number of weeks ago, and he informed me he had not made any Discovery mirrors for months, and would not assure that a Discovery scope would have his mirror in it. Discovery is selling a lot of scopes and I doubt they have some kind of stock pile of mirrors.
Ostahowski is selling his mirrors from his own business (www.ostahowskioptics.com)