Which mirror better-Zambuto, Discovery or Orion UK
Posted 17 January 2013 - 02:12 PM
Which wiould I rather have in my posssesion? The Zambuto
Posted 17 January 2013 - 02:26 PM
I took the liberty of copying your post to email and sending it to Terry O. He'll be happy to read it.
use for 1 month a mirroir 17 "5 F/D 4 Zerodur Ostahowsky optic, and since I make of the astronomy ( 35 years) it is certainly the best optics through which I observed!!!
In visual in December I was able to observe details of all the satellites jupiter in 900X, it was extraordinary!!! No light diffusion, What proves a roughness of the optical surface very low;Fabulous!!!
Terry possesses a workshop and a excellent interferometric banns test
some picture of mi new scope : http://jp-brahic.che...ice.fr/t450.htm
Posted 17 January 2013 - 04:01 PM
I paid $ 650.00 coated and shipped for my 10 inch F6 Zambuto. But this was back in April 1999. If I was to sell it today, I think I'd make a bit of coin. No, it's not for sale. This mirror is the best single investment I've ever made in the hobby.....and I'm not talking about the financial part....instead I'm talking about the quality of the purchase and the enjoyment I've had using the mirror over the years.
Posted 28 January 2013 - 02:32 AM
Posted 28 January 2013 - 04:03 AM
Of note, in a newtonian system collimation is arguably the most important as mis-collimation can introduce many more wave-multiples of error than comparing decent vs. excellently figured mirrors. I recall some articles in which a person stated after learning about "proper" collimation his previously poor scope became an excellent scope. Not to imply anything about the OP, just to say there are other factors.
On the other hand, mass produced optics, like any other product, will have a variation in quality. This means some will be outstanding (more than +2SD outside mean) and some will be appalling (hopefully QC picks those up). Is it possible that some of the excellent mass produced ones will exceed a ZOC or a 1/10 wave Orion UK mirror? Absolutely. Its even possible (statistically and theoretically, of course) that its surface smoothness may be a few atoms thick, the scope will hold up excellently mechanically thus you'll get wonderful views.
The main question is:Can you accurately select for such a scope? Most of the time unless the store has such a scope in hand and the owner is willing to do that for you, its nigh on impossible.
So the best approach is to take the quality of the mean and compare that with the premium mirrors. In which case you'll find that most observers will prefer the premium mirror over randomly selected mass-production scopes. Therein lies the value of these "premium" mirrors - you are buying a known quantity.
Put it in another way: If you went to the Supermarket and wanted to buy a canned item, say a premium canned meat that costs $10/per can. Now suppose the roof blew off the supermarket in a hurricane and the rain soaked off all the can labels. Would you then also be willing to pay $10 for an unlabelled can with unknown contents and quality. I don't think so. But would an unlabelled can still do its job (providing nutrition)? It would, but you'll probably be willing to pay less in case the food is of a lower quality.
Posted 28 January 2013 - 07:00 AM
This discussion reminds me somewhat of the ones that take place on the photography forums I visit. Instead of Zambuto it's Leica and Zeiss. Some people swear that Leica optics are worth many times what you might pay for Nikon, Canon, or other lesser known brands. Others think there's really no difference. I think myself that there is a difference between these photographic optics (I don't know enough about telescope mirrors), but that the user has to be quite discerning, which usually comes with experience. Like with many other manufactured items, you pay a heavy price to get the best.
I think that a lot of folks believe this, as it seems reasonable. However, and in my experience, it is not true when it comes to telescopes. There are a lot of cases where the optics are simply not very good, and that difference is readily visible through the eyepiece. I think that if I buy a camera, it will work well. If I buy a scope, it might not work well and in fact, at the lowest price points, it is guaranteed to not work as well (mechanically) as a lot of folks will expect. I realize that many people will find this incredible, but that is my experience.
Posted 28 January 2013 - 08:55 AM
I think that if I buy a camera, it will work well. If I buy a scope, it might not work well
I wish this were the case with cameras... I bought one of the 35x "superzoom" Canons last year, bought new directly from Canon. It was horrible, I couldn't believe something so bad could get through their automated QC. I sent it to their repair facility on warranty, they replaced the whole lens/CCD assembly, a human being tested and adjusted it, flashed it with newer firmware, and it is now the excellent camera that I'd read about.
It's tough times in optical businesses lately. Lots of corners being cut to stay afloat. If, as a customer, you don't insist on reasonable quality, you are relying on luck and may not get it.
Posted 30 January 2013 - 01:54 PM
People like Zambuto and Harry will stand behind their quality claims. You pay more but quality always has a higher price.
Posted 30 January 2013 - 06:22 PM
John my experience mirrors yours exactly. I have a 15" Obsession and the stock 2" thick pyrex OMI mirror is excellent but can take awhile to cool. I just replaced mine with a ZOC 14.5" but I would not hesitate to recommend the OMI. In fact I plan on sticking my OMI in an old Discovery 16" split-tube (if I can find an empty one) and fitting it out with multiple fans so I have more thermal control.
My 14" Zambuto mirror on the other hand is only 1.3" thick and cools beautifully, consequently it delivers to its maximum performance potential a lot more often. I have the same sensors on the 14" scope and it very quickly gets to within 1 deg C to 2 deg C of ambient quite quickly. That's not to say the OMI mirror is the equal of the Zambuto mirror optically, it isn't, but its still a very good mirror restricted only by its thermal properties, not its optical quality.