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.
Mar 2, 2019
Great quality, reasonable prices, and excellent safety...Pros: Cons: Comments:
The mirrors arrives totally secured... Not even a scratch... The prices are very reasonable... You have many great options to choose from... Only thing is: there must be better and less expensive shipment options...
This review was provided courtesy of AgenaAstro.comSep 3, 2017
Decent MirrorsPros: Cons: Comments:
I don't know much about astronomy but I took a chance on these mirrors. It was worth it Images are clear and bright. The mirrors are thick and sturdy. They were well-packaged. I would recommend this business.
This review was provided courtesy of AgenaAstro.comOct 2, 2016
Very nice optics at a reasonable pricePros:
Lightweight,Accurate,Easy to Use,Quality LensesCons: Comments:
On the first night out with the GSO 8" f/6 optics, built into a homemade tube assembly, a simple star test revealed that the figuring was certainly very adequate. I've been using f/4 and f/4.5 mirrors for many years and had almost forgotten just how sharp a well made f/6 mirror can be. I was delighted to see that star images were sharp, crisp pinpoints, giving the impression I was looking through a high-end refractor. It is possible to obtain higher quality optics -- but at an exorbitant cost, and what you would gain for all that extra money doesn't amount to much for the average observer. These GSO mirrors provide good quality images for an amateur astronomer at a very reasonable price. From the standpoint of it being a "best value" purchase, I give it 5 stars.
This review was provided courtesy of AgenaAstro.comJan 23, 2016
Excellent quality and delivered on time!Pros:
Easy to Use,Strong Construction,Quality Lenses,AccurateCons: Comments:
I wanted to build my own telescope, so this mirror helped me achieve this goal. I'm not an expert but I find this mirror very well made and it's been a pleasure looking at the sky now.
This review was provided courtesy of AgenaAstro.comMay 30, 2013
GSO Parabolic Primary mirrors - GREAT !Pros:
Quality Lenses,AccurateCons: Comments:
This is the 8th mirror I've purchased from Agena - the first 7 were 6" f/8's which were used in an ATM course I taught resulting in 7 great little Dobs. The 8" f/6 went into my own sturdy GEM tripod mounted scope. The mirrors were all first rate and the service from Agena was superb. Highly recommended.
This review was provided courtesy of AgenaAstro.comApr 12, 2013
Very pleased - great valuePros: Cons: Comments:
I purchased the GSO 8 inch f6 primary and secondary mirror set from Agena to use in a travel scope I was building. I finished the scope a couple months back and have had the scope out multiple times. I don't know how to test mirrors but I have several dobs and have owned quite a few telescopes and can tell you that this mirror performs very well under a variety of magnifications for deep sky and on the planets. Very pleased with this purchase especially for the price. I'll likely buy another one from Agena at some point.
This review was provided courtesy of AgenaAstro.comSort by