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GSO 0.965"/1.25" 90-deg Hybrid Mirror Star Diagonal

4.9 (8 Reviews) Read Reviews Write Review
Brand GSO
Part Number ODIA-GS-GSST-HYBRID
Availability available

Product Info

Manufacturer Description

Important Note: Please note that the length of the 0.965" nosepiece, as listed below, is 15mm (0.59"). Before purchase, please make sure that the thumbscrew on your telescope is within this distance from the rear end of your focuser drawtube. Otherwise, the thumbscrew will not be able to engage and lock the diagonal. This is a known issue with some vintage telescopes in which the locking thumbscrew on the telescope is recessed by more than 0.6", and this diagonal will not work for you.

Disappointed by the lack of quality 0.965" eyepieces for your vintage telescope? Missing a diagonal for that small telescope you picked up in a garage sale? Wish you could use wider angle 1.25" eyepieces with your small spotting scope? Here's the solution you need!

Many vintage telescopes sold up to the 1960s, cheap introductory telescopes sold today, and many spotting scopes use a smaller, older, almost obsolete 0.965" diameter format for diagonals and eyepieces. Having a 0.965" barrel severely limits the number of eyepieces and accessories you can buy and use in the after-market.

This popular hybrid diagonal from GSO allows 1.25" eyepieces, diagonals, and other accessories to be used in 0.965" focusers, and at once allows hundreds of more common 1.25" format astronomy items to be used with your telescope.

GSO's hybrid 0.965"-1.25" 90-degree mirror diagonal features Al+SiO2 coatings with 92% reflectivity across the visible spectrum and a 1/10 wave mirror. The main mirror housing is made of precision molded ABS plastic and the two end barrels are precision machined from aluminum.

A unique feature of this hybrid diagonal is the use of a dual step 0.965"/1.25" chrome barrel on the telescope end. While designed primarily for use with 0.965" focusers, the step barrel also allows you to use this diagonal in 1.25" focusers (although your field of view might vignette in some situations if used in this manner). Total length of the nosepiece is 25mm (0.98"); length of 1.25" portion of nosepiece = 10mm (0.39"); length of 0.965" portion of nosepiece = 15mm (0.59").

Weight: 3.5oz; 2 end caps included. Made in Taiwan.

Please Note: This diagonal can only be used with refractor telescopes and some catadioptric telescopes like Schmidt-Cassegrain, Maksutov-Cassegrain, etc. It not meant for use with Newtonian / Dobsonian reflector telescopes or other variants of Newtonian telescopes.

Reviews

4.9 (Based on 8 Reviews) 100% of reviewers recommended this product.
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    1. Guest

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      Review by Henry S.
      1524711536
      Apr 25, 2018

      5.0 Better than a generic

      Pros:

      Cons:

      Comments:

      Perfect fit for the classic telescope

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

    2. Guest

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      Review by Allan C.
      1510272234
      Nov 9, 2017

      5.0 Excellent Hybrid Diagonal

      Pros:

      Cons:

      Comments:

      This is the perfect way to make use of my telescopes with .965 visual backs with my collection of 1.25” eyepieces. No vignetting that I can detect and excellent image quality.

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

    3. Guest

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      Review by John B.
      1500180334
      Jul 15, 2017

      5.0 Angle adapter

      Pros:

      Cons:

      Comments:

      It is exactly what I needed

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

    4. Guest

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      Review by ERROL T.
      1492500488
      Apr 18, 2017

      5.0 Hybrid star mirror

      Pros:

      Cons:

      Comments:

      This particular star diagonal is very good.

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

    5. Guest

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      Review by Tim of South Jersey.
      1459900800
      Apr 5, 2016

      5.0 Bought to make an old scope more useful

      Pros:

      Sturdy,Strong Construction

      Cons:

      Comments:

      I added this diagonal to an old Meade 60AZ sold by Natural Wonders. The piece was better than the stock diagonal, sturdier, better materials. The transition to the 1.25" eyepiece rendered no negative effects that I can see. If there is a slight bit of vignetting, it is negligible and I do not notice it. I bought it to work with the Revolution Imager and it fits fine. It is heavier than the old piece as I would expect from metal and thick plastic components compared to thin plastic. Very satisfied.

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

    6. Guest

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      Review by DennyT of Ventura, CA.
      1418860800
      Dec 17, 2014

      5.0 Excellent Performance for the Price!

      Pros:

      Accurate,Easy to Use,Strong Construction,Lightweight

      Cons:

      Comments:

      As the description suggested, I bought this diagonal for a telescope I found at a garage sale (1980s Meade 60mm f/15 #291 w/mount+finder; MIJ). I also needed a star diagonal for a scope that had a 1.25" barrel, so this was the perfect choice for both. I am impressed with the build quality of this diagonal, I especially love the look and feel of the machined barrels. The endcaps are a nice touch.

      I had a tough time deciding between this diagonal, the erect prism version, or the dielectric version. I went with this one because I felt the specs were good enough for me and I didn't need an erect image.

      I am very happy with the views this diagonal provides in both .965" and 1.25" scopes. It gives a pure, true image. I don't have any vignetting on 1.25" scopes with standard plossl/MA EPs ranging from 4mm-26mm. I would love the option to purchase a standard 1.25" barrel just in case, though!

      All in all, this is an excellent product for the price. I would imagine the gains you'd get by spending a lot more would be marginal.

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

    7. roaesch

      roaesch New Member

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      Review by Ralphiebaby of Moscow, ID.
      1413936000
      Oct 21, 2014

      4.0 GSO 0.965/1.25" Diagonal for C-90

      Pros:

      Strong Construction,Compact,Lightweight,Accurate

      Cons:

      Comments:

      I use this in an old C-90 SCT, it works but the set screw just hits the end of the barrel. I wish the 0.965" barrel were longer.

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

    8. Guest

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      Review by John7 of Oshawa, Ontario Canada.
      1408406400
      Aug 18, 2014

      5.0 Renews old 0.965 Telescope to 1 1/4"

      Pros:

      Quality Lenses,Accurate,Lightweight,Easy to Use,Strong Construction,Compact

      Cons:

      Comments:

      Get's the most out of my old 0.965 Bushnell Sky chief I Telescope D=60mm F=700 mm
      Up grades to 1 1/4 inch eye pieces, Big is better.

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

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      Specifications

      Manufacturer GSO