If you want a high-end mirror diagonal for your Schmidt-Cassegrain telescope, this GSO 2" Quartz Dielectric Diagonal Mirror is an excellent choice. GSO's 2" SCT diagonal features dielectric coatings with 99% reflectivity across the visible spectrum and a 1/12 wave quartz mirror. The all metal diagonal body is CNC machined. The combined result is a superb diagonal offering excellent mechanical and optical quality at a great price. Dielectric coatings are more durable than regular or enhanced aluminum coatings, so you will enjoy years of excellent performance from this product. Diagonals with comparable quality and specifications often sell for $200 or more in today's astronomy market.
High quality diagonal mirrors are usually made of BK7 glass. Quartz glass goes a notch higher - it offers greater thermal stability, resulting in minimal thermal expansion and contraction as compared to other glass types. The result is a minimal, if any, shift in focus due to temperature changes over long observation sessions, making this quartz diagonal ideal for photographic and imaging applications.
You can attach this diagonal directly to Schmidt-Cassegrain telescopes and many Maksutov-Cassegrain telescopes, as long as there is a SCT male thread on the telescope. The standard SCT thread is a 2"x24 tpi thread.
A 1.25"-2" adapter is included so you can use this diagonal with 1.25" or 2" eyepieces. The 1.25" and 2" holders both feature a brass compression ring, so your eyepiece barrels will not be scratched by the set screw. The 1.25"-2" adapter is also threaded to accept 2" filters. The clear aperture is 38.2mm. The diagonal comes in a very nice foam-fitted storage box and includes 2 end caps. Weight = 1lb-4oz. (with 1.25" adapter); 1lb-1oz. (without 1.25" adapter). Made in Taiwan.
Sep 18, 2017
GSO 2" Quartz SCT DiagonalPros: Cons: Comments:
Bought this to attach to a 102mm Mak-Cass telescope. Bought an SCT adapter for the back of the telescope barrel, attached a 2" 0.63 focal reducer to the adapter, then the 2" GSO diagonal to the reducer.
Works well. Had to make a gasket as the threaded ring of the SCT band on the diagonal was too deep. Made up a plastic ring about 0.3 mm thick to compensate and it works ok, but that would be why I give it a 4 star rating.
Works great for both my 1.25 in and 2 in eyepieces.
This review was provided courtesy of AgenaAstro.comOct 7, 2014
Funky tightening ringPros:
Strong Construction,Quality LensesCons:
Difficult to UseComments:
My threaded ring didn't tighten correctly. You could tighten it and then it would not want to come off. As I see it, the threaded ring was too close to the hardness of the Meade threads and would cause this galling. Agena sent me a new front piece to try and it perectly solved the problem. It even made it quiet while screwing on rather than squealing. I gave it three stars because of the hassle; however, it would have been worse had Agena service not been so great. They are great!
This review was provided courtesy of AgenaAstro.comSep 21, 2012
Accurate,Easy to Use,Strong ConstructionCons: Comments:
Got this to use with my CPC 800. What difference this thing makes, its like having a new scope. Much better than the stock diagonal.
This review was provided courtesy of AgenaAstro.comNov 4, 2011
Why Pay More?Pros:
Strong Construction,Accurate,Quality LensesCons: Comments:
I've used the more expensive brands and I cannot tell any distinct difference in build or optical quality. You can pay over twice as much and get the same exact views and durability.
This review was provided courtesy of AgenaAstro.comNov 4, 2011
Strong Construction,Easy to Use,AccurateCons: Comments:
I bought this for a 10" Meade SCT f/6.3 I purchased. It is a beautiful product; from the packaging all the way to the finish on it is amazing. I never tried a 'regular" mirror so I can't say whether it really has a "brighter" return but it does provide a beautiful picture.
Standard wonderful product from GSO at a good price. I'd buy it again given the choice.
This review was provided courtesy of AgenaAstro.comOct 10, 2010
Works with Meade Series 4000 f/6.3 Focal ReducerPros:
Short light pathCons:
The Meade Series 4000 f/6.3 Focal Reducer/Field Flattener for Schmidt-Cassegrain Telescopes is a nice accessory but it has limitations when used with some 2" diagonals as you can't ever reach focus.
Because of the shorter light path of the GSO 2" diagonals for SCTs I can now easily reach focus with all my 1.25" and 2" eyepieces, unlike my older Meade 2" diagonal that is now in retirement.
This review was provided courtesy of AgenaAstro.comOct 3, 2010
One small problem to be aware of...Pros:
Quality LensesCons: Comments:
From the product description: "The 1.25"-2" adapter is also threaded to accept 2" filters."
Yes you can screw a 2" filter into the adapter but some 1.25" eyepieces may contact the filter and damage it. A parfocal ring on the eyepiece or a short 2" spacer is needed to prevent this problem.
This review was provided courtesy of AgenaAstro.comNov 9, 2009
It works for me.Pros:
The only reason I gave it 4 stars instead of 5 is because of the threaded front has to be loosened in order to adjust the eyepiece closer to the viewer. Furthermore, when adjusting this diagonal it might cause damage to the threads on the SCT from constant tightening and loosening-especially when using a heavier eyepiece like the Ethos series that I use.
Good note is that both the front thread and the rear eyepiece adapter can be removed for easy cleaning of the quality dielectric coated mirror.
This review was provided courtesy of AgenaAstro.comMay 26, 2009
Quality at a great pricePros:
This diagonal compares well with units costing much more money. Construction is first rate and the mirror is very well polished. Very usable in Sct type scopes of various manufacturers.
This review was provided courtesy of AgenaAstro.comMar 26, 2009
GSO IS A GOOD CHOICEPros:
QUALITY MIRROR,Strong ConstructionCons:
Very bright mirror, well constructed diagonal, you tighten the ring around your lens barrel so you are not digging a hole into your beautiful lens barrels as you are with the diagonals supplied with most scopes from the factory. The body is very heavy so remember you must make sure your balance is correct if you are using motors to go to and slew. It was not to large for the 8" sct I put it on and it fit under the fork comfortably when packed away. Found the 2" diagonal will allow you to use your 1.25 lenses as well as my 2" lenses so there is no reason not to upgrade your sct to a 2" and get all the light comming down the 2" tube from the secondary lens. OVERALL I found a difference from the 1.25 that I could notice and the gso mirror after being cleaned upon arrival was just beautiful and the price was great for what you get. I do not believe any 2" diagonal is any better then this gso model at this very low cost.
This review was provided courtesy of AgenaAstro.comSort by