For years, GSO has made dobsonian telescopes sold under various labels. Users of these scopes know the excellent quality of the optics included, and they have a well-deserved reputation for being the finest mirrors in their price range. We are now pleased to offer virtually the entire line of GSO's Newtonian optics in the US market.
GSO's parabolic primary mirrors are perfect for those who want to build their own telescopes or replace mirrors in older ones. Ranging in aperture from 6” to 16” and offered in various f-ratios, these mirrors are made from optical grade BK-7 glass. All mirrors have a reflective aluminum coating with a reflectivity of 92-93%. The aluminum coating is protected by a silicon oxide (SiO2) over-coating. GSO's elliptical flat mirrors have the same high quality as their parabolic primary mirrors.
GSO uses high-volume, state-of-the-art, high quality manufacturing and test lines. GSO guarantees diffraction limited performance, but their mirrors typically have a mirror surface quality of 1/16 wave RMS at least, and often better. This very smooth mirror surface results in excellent optical performance with practically no light scatter.
Most parabolic mirrors will have 2-4 minor uncoated areas along the edge of the mirror. See photo 3 above for an example. These are caused by the clips used to hold the mirrors in the coating chamber. Note that these are not defects. A couple of these uncoated edge strips will typically be covered up by the clips in your mirror cell anyway.
Q. Is a test report included with each mirror?
A. No. GSO tests each mirror via laser interferometry before shipping, but does not provide individual test reports.
Q. Is the primary center-dotted?
A. Sometimes yes but mostly no. It just varies from batch to batch.
You can easily center-dot the primary yourself if the mirror you receive is not dotted. Instructions to do this are readily available on the internet. If you want a center-dotting sticker, just request one from us at the time you place your order.
If you want a mirror that does not have this center dot, please check with us before your purchase. Removing the center dot is not easy or recommended. If the mirror already has a center dot but you do not want it, we recommend that you not purchase this item.
Apr 24, 2019
Highly RecommendedPros: Cons: Comments:
Once my order was made, it arrived in Canada at my house in days. The quality of the mirror is excellent. It replaces a mirror I ground and polished years ago, but was lost in a move. Thanks for great service and outstanding quality product.
This review was provided courtesy of AgenaAstro.comJan 9, 2018
Great set of mirrorsPros: Cons: Comments:
Speedy service, the mirrors arrived well packaged for the trip with no problems. I will use the mirrors to make a 6 inch Newtonian telescope. I can’t wait to test them. I would order again from this site
This review was provided courtesy of AgenaAstro.comMar 11, 2016
Great valuePros: Cons: Comments:
Speedy service, well packaged for the trip. Used to make a 6 inch Dobsonian for a 6th grade class. Excellent and clear views when the scope was finished. Would order from you again, and have recommended the same to several of my teacher friends.
This review was provided courtesy of AgenaAstro.comFeb 4, 2016
Perfect ParabolaCons: Comments:
This mirror gives the best detail of any mirror I have ever used. I tested it with my Foucault tester and it is near perfectly parabolic all the way to the edge.
This review was provided courtesy of AgenaAstro.comDec 7, 2013
Excellent quality mirrorPros:
On Time Delivery,Good PackagingCons: Comments:
This mirror exceeds the quality of the original and was a direct replacement for my 40+ yr old telescope. I did not have to modify the mirror mount or adjust the focal plane.
This review was provided courtesy of AgenaAstro.comSort by