More Information Price $69.95 Weight 5.5 oz. Warranty 2 years

The Astro-Tech diagonal has state-of-the-art 46-layer dielectric mirror coatings for a full 99% reflectivity. In addition to higher reflectivity than the 88% of a conventional aluminum diagonal or the 96-97% of an easily-tarnished silver diagonal, the durable ion-deposited dielectric coatings on the mirror’s finely-polished 1/10th wave BK7 optical glass substrate also provide higher contrast and resolution during critical planetary, lunar, and binary star observations.

The mirror housing is precision-machined from solid aluminum, rather than simply flimsy Bakelite plastic or a sheet metal stamping, as you’ll find with ordinary diagonals. A rigid machined metal backplate with stainless steel hardware holds the mirror in perfect optical alignment in the machined body. The interior of the body is anodized an antireflective matte black. The focuser-side barrel is also anodized antireflective matte black, and is internally antireflection threaded for even higher contrast. The barrel is threaded to accept standard 1.25” filters.

The 1.25” eyepiece holder uses a non-marring soft brass compression ring to clamp eyepieces in place, rather than a thumbscrew that can scratch an eyepiece barrel by tightening down on it directly.

A shallow slanted groove cut into the outside of the focuser-side barrel engages with the scope’s visual back or eyepiece holder thumbscrew to act as a safety stop. This keeps the diagonal from falling should the scope’s thumbscrew loosen slightly from cold or use. Dust covers are provided for both sides of the diagonal.

This premium 1.25” diagonal works with virtually any Schmidt-Cassegrain, Maksutov-Cassegrain, or refractor that uses a 1.25” star diagonal,. It will provide a visible improvement over the scope’s factory-supplied diagonal. The newly designed body of the Astro-Tech diagonal is more compact than previous diagonals. This essentially eliminates any possibility of the diagonal bumping into the drive base of a short fork arm catadioptric when the scope is pointed at the zenith. This Sky & Tel Hot Product gives you all the visual performance your scope is capable of delivering, at a price that’s very affordable.