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GSO 1.25" 90-deg 99% Dielectric Mirror Diagonal

5.0 (1 Reviews) Read Reviews Write Review
Brand GSO
Part Number

Product Info

Manufacturer Description

GSO's new 1.25" dielectric diagonal continues their tradition of offering superb products at excellent prices. This beautiful1.25" mirror diagonal features a BK7 mirror that is precision ground to a flatness of 1/10th wave (minimum) and features dielectric 6-layer enhanced silver coatings with an over-coat protective layer for a light efficiency of over 99% reflectivity across the entire visual spectrum. The clear aperture is 27.9mm.

The mechanics of this diagonal are also top-notch. The robust aluminum body and attachment barrels are precision CNC machined to strict tolerances from solid stock throughout. The 1.25" nosepiece features a safety groove and is threaded to accept standard 1.25" astronomy filters. The 1.25" eyepiece holder does not have a brass compression ring, but it includes an internal safety stop to prevent long barrels on some eyepieces and barlows from hitting the diagonal mirror. The diagonal sports a handsome anodized finish.

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.

The diagonal comes in a nice foam-fitted storage box and includes 2 end caps. Weight = 5.7oz.. Made in Taiwan.


5.0 (Based on 1 Reviews) 100% of reviewers recommended this product.
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    1. rmscott59

      rmscott59 New Member

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      User Notes:
      Review by rms of San Francisco, CA.
      Apr 7, 2014

      5.0 A great value diagonal!


      Quality Lenses,Easy to Use,Strong Construction



      This is a great diagonal. I have a GSO Quartz and an Astro Tech Dielectric and can see no difference visually between them and this GSO. I love this model because it has no brass compression ring. I personally don't like the brass compression ring as it tends to snag the eyepiece as you insert/ remove it. I refit the lock thumbscrew with a nylon one to prevent scratching my eyepieces. THIS IS A GREAT DIAGONAL FOR A GREAT PRICE!

      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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