This Celestron 2" mirror star diagonal for catadioptric telescopes has Starbright XLT enhanced aluminum multicoatings for a reflectivity of better than 96%. They're the same high tech mirror coatings that are used to get industry-leading optical performance out of Celestron telescopes costing over $6600.
The diagonal has a physically short nosepiece and SCT rear cell attachment ring to clear the drive base on your telescope. You don't have to buy a special short version of the diagonal or special adapters to let it swing through your 8" scope's fork arms, as you do with some higher-priced competitive diagonals.
The SCT rear cell attachment ring threads directly onto all Celestron 5" and larger SCT rear cells and onto the rear cells of those Meade SCTs that do not have the electric microfocuser as standard equipment, These include Meade's older 2080 and 2120 scopes; all LX3, LX5, LX6, and Premier scopes; all current and past LX90s; and all earlier LX200 scopes that were supplied without microfocuser. The diagonal will thread onto a Meade microfocuser-equipped scope if you install the SCT rear cell ring that came with the Meade focuser into the microfocuser's 2" drawtube.
The diagonal uses an interferometer-tested 1/10th wave first-surface mirror for sharp, distortion-free images. The mirror housing is machined from solid aluminum, rather than simply a flimsy plastic box or a sheet metal stamping, as you'll find with ordinary diagonals. The solidity of the construction is mirrored in the diagonal's substantial 17 ounce weight.
The interior of the body is lined with light absorbing foam, in addition to being anodized an antireflective matte black. The short nosepiece that holds the SCT rear cell attachment ring is internally antireflection threaded for high contrast. The attachment ring is knurled for a sure grip so it can be easily loosened, allowing you to rotate the diagonal to the most comfortable observing position.
Rather than using a metal thumbscrew that contacts eyepiece barrels directly and can scratch them, the diagonal's 2" eyepiece holder uses a non-marring soft brass compression ring to firmly hold 2" eyepieces and the supplied 1.25" eyepiece adapter. The knurled chrome thumbscrew that operates the compression ring is a full 1/2" in diameter to provide a sure grip in cold weather when wearing gloves or mittens.
The 1.25" eyepiece adapter also uses a compression ring to hold eyepieces in place. The 1.25" adapter is threaded to accept 2" (48mm) filters. It has a slanted groove cut into the outside of its 2" barrel. This engages with the diagonal's compression ring to act as a safety stop to keep the adapter from accidentally slipping out of the 2" diagonal should the compression ring loosen during use. Dust covers are provided for both the 1.25" adapter and the diagonal's SCT attachment ring. The diagonal comes in a foam-fitted locking aluminum-frame case for storage and protection.
