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Celestron Dielectric Star Diagonal -2-In with Twist-Lock

SKU : CE-93573

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  • Enjoy better views through your telescope with this premium diagonal featuring diffraction-limited optics and dielectric coatings.
  • Provides a 90° viewing angle, perfect for more comfortable viewing through refractor and Cassegrain-type telescopes.
  • 58 layers of dielectric coatings provide an over 99% reflective surface, ensuring the maximum amount of light collected by the telescope reaches the eyepiece.
  • Twist-lock keeps the eyepiece centered in the diagonal to provide better optical alignment.
  • Includes a step-down adapter, so the diagonal accepts eyepieces, Barlow lenses, threaded filters, and other accessories in both 2-inch and 1.25-inch sizes.
  • Two interchangeable adapters allow you to switch between a Schmidt-Cassegrain thread adapter and a 2-inch barrel adapter so you can use this diagonal with a wide variety of telescopes.


Product Details

  • The Celestron Dielectric Star Diagonal -2-In with Twist-Lock: Now you can get maximum light transmission without loss of optical quality with the Celestron Dielectric Star Diagonal, in the 2-Inch size with Twist-Lock. Upgrade your existing star diagonal to this premium one and enjoy brighter, sharper images without purchasing an entirely new telescope.

    This star diagonal reflects the telescope's light path 90° to provide a more comfortable viewing angle. In addition, the glass has 58 layers of dielectric coatings, which provide an over 99% reflective surface, delivering the maximum amount of light to the eyepiece. This 2-inch star diagonal has the added benefit of allowing you to use larger 2-inch eyepieces with your telescope, providing a wider field of view, or standard 1.25-inch eyepieces with the step-down adapter.

    The twist-lock eyepiece holder secures eyepieces while keeping them centered in the diagonal, thus providing best opto-mechanical alignment between the telescope and eyepiece. Unlike traditional thumb screws, the twist-lock cannot scratch or engrave the barrel of your eyepieces. The diagonal has an integrated 2-inch barrel-stop that prevents 2-inch accessories with long barrels from damaging the mirror.

    All of this diagonal's mechanical parts are made of machined black anodized aluminum, except the twist lock rings, which are orange anodized for visibility. The interior of the Schmidt-Cassegrain adapter and 2-inch barrel are glare threaded and painted flat black to prevent glare. With all its features and these high-end finishes, the Celestron Dielectric Star Diagonal, 2-inch with Twist-Lock is one of the highest quality 2-inch star diagonals that Celestron has ever offered.

    This diagonal also comes with two interchangeable barrels to provide flexibility in connecting the diagonal to a wide variety of telescopes without the need for additional adapters. For telescopes, like refractors, which accept 2-inch barrels in their focuser, a standard 2-inch barrel is included. For Schmidt-Cassegrain telescopes (SCTs) that use a threaded connection to the focuser, a barrel with SCT threads is included. Both barrels thread onto the diagonal housing, providing a secure connection to the diagonal.

    Standard Star Diagonals vs Dielectric Star Diagonal

    The key specifications for a star diagonal are its reflectivity and its optical quality. This diagonal delivers top performance in both categories, with an over 99% reflective mirror and diffraction-limited optical quality. This ensures that virtually all the light collected by the telescope will reach the eyepiece without the diagonal affecting optical performance. Using a lower quality star diagonal can both dim the view and degrade optical quality. You can enjoy better views from your telescope by simply swapping out its diagonal for a premium one, like the Celestron Dielectric Star Diagonal.


    Image note: Filter shown for use purposes only, available for separate purchase.


  • specifications

    Accessory Size1.25" and 2"
    Free ShippingYes
    Glass TypeBak7
    Weight19 oz
  • included items

    • Celestron Dielectric Star Diagonal, 2-inch with Twist-Lock.
    • 1.25-Inch Twist-Lock Step-down Adapter.
    • 2-Inch Schmidt-Cassegrain Threaded Adapter.
    • 2-Inch Barrel Nosepiece Adapter.
    • 2-Inch Lens Cap.
    • 1.25-Inch Lens Cap.


Product Reviews

Customer Reviews
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Ronald C.
United States United States

Celestron 2" Star Diagonal Dielectric

The price was reasonable, delivery on time and the product was of high quality. I have an old 2" star diagonal and there is no comparison to the new Celestron unit. The Celestron Star Diagonal is more sturdy, and the twist-lock is more precise. I haven't had a chance to use the new diagonal, but I do know that the coating technology has advanced far beyond that on my old unit.

United States United States

Outstanding Diagonal

I have used it for a few days. To me it is worth the cost. The twist lock is very convenient and the transmission and reflection is terrific. I can tell a difference in the standard diagonal and this one.

John M.
United States United States

Twist Lock Diagonal

Love it so far. Very easy to use. Locks eyepieces tightly. Much easier to use that small finger screws.