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 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.
Besides parabolic primaries, we also offer matching GSO secondary elliptical mirrors, mirror cells, and spiders (all sold separately).
Most parabolic mirrors will have 2-4 minor uncoated areas along the edge of the mirror. See photo 2 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.
Aug 22, 2018
Nice swap out for a cheap scopePros: Cons: Comments:
I found a 6-inch telescope at a thrift store for about $30. It was okay to look at the moon but Stars never really resolved points. The planets were round but liked details. They also didn't really resolved two discs. It was clear that the mirrors in this department store telescope were lacking so, I purchased this and a gso secondary to go with it. I was not disappointed! One would not call a 6 in F5 mirror a planetary scope, yet when pushed to the absolute limit with a 6 millimeter eyepiece and a 3X Barlow, Saturn looks like a beautiful sphere surrounded in a bed of rings. Not like one of those weights with the two handles on either side, which is common in smaller Scopes. The cloud bands are easily discernible as is the Cassini Division and other ring features. This is a very high-quality mirror! And an easy swap out for a cheap scope for an instant upgrade.
This review was provided courtesy of AgenaAstro.comAug 22, 2018
GSO Parabolic Primary Mirror - 6" f/5Pros: Cons: Comments:
I made the mistake of buying a cheap Twin Star telescope, that had a spherical mirror. The GSO parabolic mirror has turned it into a usable tool, that I can now enjoy.
This review was provided courtesy of AgenaAstro.comSep 25, 2017
Nice mirror, well packetPros: Cons: Comments:
Express shipping, I was repairing a damaged NPZ-TAL-2 scope, making it shorter.
I received the miror in a safe double box with polystyrene protection, good optic cover.
After many difficulties, not due to it I finally collimated the scope and took fast a Moon image that appears very good.
The scope : http://astrosurf.com/uploads/monthly_2017_09/IMG_20170919_151548.thumb.jpg.555781c9f56484cec2babc5d3f3c649c.jpg
Thanks to Agena for this over average optic.
lylver on Cloudy Nights
This review was provided courtesy of AgenaAstro.comAug 17, 2017
Exactly what I asked forPros: Cons: Comments:
I ordered a 6" f/5 primary mirror with the 50mm secondary as a bundle. I got exactly what I asked for in pristine condition, which I appreciate. The customer support was excellent; they answered my call immediately and I was talking to a real person who gave me helpful advice. To an outsider, this website may seem a little fishy, though (I know I was suspicious at first), but now I will definitely recommend this company to friends, family, etc.
This review was provided courtesy of AgenaAstro.comApr 4, 2017
6 inch, f5 parabolic mirrorPros: Cons: Comments:
Mirror arrived promptly & appears to be as advertised. Used it in a Newtonian richest field telescope & it gave me great views of Jupiter & the moon. Plan to use it with a Mallincam SkyRaider video camera for public viewing. Assumed that it was an accurate f5, focal length of 30", when I did all the calculations. Took a chance using a very low profile Crawford focuser with only 1 1/2" of travel, and the mirror came to focus right where it was supposed to. This is the 5th telescope I have built.
This review was provided courtesy of AgenaAstro.comSort by