Ensure maximum light transmission without loss of optical quality with the Celestron Dielectric Star Diagonal, 2” 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” star diagonal has the added benefit of allowing you to use larger 2” eyepieces with your telescope, providing a wider field of view, or standard 1.25” eyepieces with the stepdown 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” barrel stop that prevents 2” 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 Schmidt-Cassegrain adapter and 2” 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” with Twist-Lock is one of the highest quality 2" 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” 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.

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.