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Celestron Dielectric Star Diagonal with Twist-Lock (2-inch)Features:

  • Premium diagonal featuring diffraction-limited optics
  • Dielectric coatings
  • Provides a 90° viewing angle
  • 58 Layers of dielectric coatings
  • Twist-lock cannot scratch or engrave the barrel of eyepieces
  • Twist-lock rings are orange anodized for visibility
  • Mechanical parts are made of machined black anodized aluminum
  • Interior of barrel is painted flat black to prevent glare
  • Twist-lock keeps the eyepiece centered in the diagonal
  • 2 Interchangeable adapters for flexible connectivity

Product Description:

Ensure maximum light transmission without loss of optical
quality with the Celestron Dielectric Star Diagonal, 2-inch with
Twist-Lock. Upgrade your existing star diagonal to this premium one and
enjoy brighter, sharper images without replacing your 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.

Twist-Lock Features:

twist-lock eyepiece holder secures any 2-inch 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 twist-lock has an integrated 2-inch barrel stop that
prevents 2-inch accessories with long barrels from damaging the mirror.
All the 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 barrel is 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. 

Interchangeable Lens:

This diagonal also
comes with two interchangeable barrel adapter 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” barrels in their focuser, a standard 2” barrel is included. For
Schmidt-Cassegrains (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.

Dielectric Star Diagonal Advantages:

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.

What's in the Box:

  • Celestron Dielectric Star Diagonal with Twist-Lock (2-Inch)
  • 2-inch to 1.25-inch Stepdown Adapter
  • SCT Adapter
  • Dust Cap


  • Diagonal size: 50.8mm (2-inch)
  • Diagonal type: Mirror
  • Glass material: BK7
  • Coatings: Dielectric, 58 layers
  • Reflectivity: Over 99%
  • Optical quality: Diffraction limited
  • Eyepiece holder: 2-inch, Twist-Lock
  • Compression ring: Yes, dual rings for 2-inch eyepiece holder and single ring for 1.25-inch stepdown adapter
  • Housing construction: Machined aluminum black anodized
  • Barrels:
    • 2-inch barrel (for connection to 2-inch focusers)
    • SCT Adapter (for connection to SCTs)
  • Barrel interior: Glare threaded and painted flat black
  • Threads for filters: 2-inch filter threads
  • Dimensions: 152.4 x 76.2 x 101.6 mm (6 x 3 x 4-inch)
  • Weight (with stepdown adapter): 19 oz (538.6 g)

Filed under: Eyepieces & Accessories