Upgrade your existing star diagonal with this premium Celestron 2" Dielectric Star Diagonal with Twist-lock ensures maximum light transmission without loss of optical quality. 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.
All the diagonal’s mechanical parts are made of machined black anodised aluminium, except the twist lock rings, which are orange anodised for visibility. The interior of the barrel is glare threaded and painted flat black to prevent glare. 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 step-down-adaptor.
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 adaptors. 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.
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.
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.
The twist-lock eyepiece holder secures any 2” eyepieces while keeping them centred 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” barrel stop that prevents 2” accessories with long barrels from damaging the mirror.
Diagonal size 50.8mm (2")
Diagonal type Mirror
Glass material BK7
Coatings Dielectric, 58 layers
Reflectivity Over 99%
Optical quality Diffraction limited
Eyepiece holder 2", Twist-Lock
2"-to-1.25" Step-down adaptor Included, Twist-Lock
Compression ring Yes, dual rings for 2" eyepiece holder and single ring for 1.25" step-down adaptor
Housing construction Machined aluminium black anodised
Barrels Comes with 2" barrel (for connection to 2" focusers) and SCT adaptor (for connection to SCTs)
Barrel interior Glare threaded and painted flat black
Threads for filters 2" barrel and 1.25" step-down adaptor have 2" filter threads
Dimensions 152.4mm x 76.2mm x 101.6mm (6" x 3" x 4")
Weight 19 oz (538.6 g) (with step-down adaptor)