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20\" f/4.2 Sandwich Parabolic Telescope Mirror For Sale

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20\" f/4.2 Sandwich Parabolic Telescope Mirror :
$1550.00

The reserved price is $1500!

It will be ready to ship in about 2-3 weeks.

There are some very thin hair line scratches on the mirror surface; which has No impact on the optical performance.

Please understand that the surface delivery (Economy Shipping)is a great value, but may take longer than10 weeks for the delivery; however it does have the online tracking andis fully insured.You agreenot to make the delivery time an issue andnot toopen a case based on the delivery timewith Paypal or eBayifthe surface delivery (Economy Shipping)is used.

Surface(US$) Air(US$)
~6+ weeks ~10 days US 138 288 US(Hawaii) 138 269 Austria 93 215 Australia N/A 264 Belgium N/A 281 Canada 83 254 Denmark 71 230 France 86 241 Germany 70 230 Italy N/A 366 Japan 74 138 Korea N/A 139 Netherleands 77 211 New Zealand 103 256 Norway N/A 349 Philippines 58 100 Russia N/A 522 Singapore 51 106 Sweden N/A 305 Switzerland 87 238 UK 83 246

This is a state of art,professional fabricated, 20\" F/4.2, revolutionary lightweight sandwich primary parabolic telescope mirror ([link removed by eBay])made of the top quality precision annealed plate glass.The mirror structurehas beenoptimized using the advanced Finite Element Analysis Modeling. It has very shortthermal equilibrium time even without fan.

Optical Aperture (Diameter): 20.00\"

S/N: 13-06-20-36K

Coating: Thestandard aluminum coating, 88% reflectivity

The special upgrade offer for the 92% Semi-enhacned coating: $115
If you would like to have this upgrade, please inform us right after winning the bid.

Radius of Curvature (ROC): 169.3\"

Focal Length: 84.7\"

PV (wavefront): 1/17.7

RMS: 1/67.6

Strehl Ratio: 0.99

Weight: ~18 kg

Total Thickness: ~50mm

For international bidders, please make sure to use the Shipping costs tool to estimate the shipping cost before you place bid! Please also provide your phone number during check out. Both UPS and USPS require the phone number for the international shipping.

You may have to payCustom fees, import duties, and VATtoreceive the package.

To ensure you have the most appropriate information regarding VAT rate in the EU, please read the following link:

http://pages.ebay.com/help/account/vat-main-selling-country.html

FAQ :

1: Is there any performance difference between mirrors made of Pyrex and mirrors made of Plate glass?

The short answer is, believe it or not, there is none. You may want to read Four Infamous Telescope Myths by Gary Seronik at: [link removed by eBay]

The article only evaluated small mirrors, but the conclusion is actually true regardless of the size of the mirror.

You may also want to read:

[link removed by eBay]

This is the site for the 100\" plate glass mirrorof Hooker Telescope, the largest solid glass mirror ever built. If those bubble filled, layered, plate glass has been good for the 100\" solid glass mirror for almost 100 years;our top grade modern day plate glass with far muchbetter quality must be good for a much smaller and muchbetter structuredmirror. The 100\" Hooker mirror does take much longer time to cool down than the 200\" Palomar telescope mirror primarily because the much more efficient honeycomb structure is used in the Palomar telescope mirror.

You canlearn more on this on our web site: [link removed by eBay]

2: What size secondary mirror should be used with this mirror?

The size of the secondary mirror depends on many factors. Here is the formula of the diameter of minor axis of the secondary: A = d + (D-d)L / F A=diameter of the minor axis of the secondary
F=focal length of the primary
d=fully illuminated fields desired
D=Diameter of the primary
L=distance from the secondary to focal plane

Normally,a secondary with 4\" minor axis diameteris recommendedfor this mirror.

3: What kind of mirror cell is recommended?

A 6-point mirror cell with the sling lateral support is recommended for this mirror.

What our customers are saying:

Last night I had “first light” with the 12.5” f/6 mirror that you recently supplied. It is truly a magnificent optic! Ronchi, knife-edge, and star tests were straight out of a textbook, and the image of Saturn was breathtaking. Despite the thin substrate, there is no hint of astigmatism. Frankly, when I purchased a Hubble Optics mirror on eBay, I was skeptical of the advertised wavefront quality. For the low price, it just seemed too good to be true. In the future, I will not hesitate to recommend your firm’s optics to friends and acquaintances. ......

Tom Dobbins
Contributing Editor, Sky & Telescope magazine (quotedby permission)

I’ve tried buying fast 8” mirrors twice through A-mart and both were dogs – terribly undercorrected, probably spherical. This mirror is way different. Stars are near pinpoints and there is no tendency to astigmatism (at least nothing that didn’t come from my eyes). I went out tonight and looked at Jupiter as soon as it became visible. Even so, it is getting pretty low in the sky and the air was pretty wavy. As near as I could tell, in the moments of stillness the images were as good as any scope I own.Star testing showed even images that were very nearly the same inside and outside of focus. Using my EZ tester (ronchi eyepiece) showed nice straight lines and no hint of TDE.As far as I can tell this mirror is a winner and will suit my needs very well. Whether or not it actually meets the specs listed on the box I can’t tell without getting it tested. But its a lot better than the other Ebay mirrors and I like it. I wouldn’t be afraid to buy another Hubbleoptics mirror...

Dave Chadsey

I just tentatively assembled my 10\" F4.7 1/17 PV wavefront mirror in my observatory and watched Jupiter and the moon last night. Although the air condition was terrible due to middle of rainy season, optical performance was exactly as I expected! The surface of Jupiter was amazing. Contrast of color was deep and details were very sharp, image edge was knife cutting, even through hazy bad seeing. The surface of the moon had an extra contrast; very very sharp edged landmark was attractive enough to keep watching hours. A hair splitting and breath taking experience, which reminded me of previous mirrors. I need to further tune up optical performance of this scope such as replacing with smaller high precision secondary mirror etc. Will report further progress.

Kazuki Yamane

More eBay Feedbackwe have received (Over 900 great reviews!)


Nice views with this mirror. Star tests are very good.

One word: amazing. Amazing packaging, amazing service, amazing product. Amazing.

alles bestens, sehr schnell geliefert

Great! the mirror is wonderful. Thank you again!

My Truss Dobson is ready tonight the first Light, Optic ist wonderfull

fast service, good foucault images and rhonchigram, great deal!

Great mirror, better than expected, wunderbar, AAA+++

Verry good quatity.Great star test results. Will purchace from this seller again

Thanks. Tripple packed! Even UPS can\'t break that..

Bien reçu ! SUPER EMBALLAGE ! Merci, à bientôt

Nice looking mirror. This is the second transction in a week. That says it all

Installed and saw Jupiter beautifully! Packaging EXCELLENT. A++

WARNING!!!:

NEVER LOOK AT OR HANDLE THE MIRROR UNDER THE SUN! THE REFLECTION OF THE SUN LIGHT MAY CAUSE BURNING OR INSTANT AND IRREVERSIBLE DAMAGE TO YOUR EYE. EYE DAMAGE IS OFTEN PAINLESS, SO THERE IS NO WARNING UNTIL IT IS TOO LATE. CHILDERN SHOULD NOT BE ALLOWED TO HANDLE THE MIRROR.

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