Product Description
This 1.25" Astro-Tech first-surface mirror star diagonal was named a Sky & Telescope Hot Product for 2007! Sky & Tel recognized that the Astro-Tech diagonal would be an outstanding value at even twice its low price. As it is, this Astro-Tech diagonal is unique among 1.25" star diagonals for its exceptional price/performance ratio. This is one premium-quality diagonal that doesn't happen to be priced like one - and it's still a hot product for many observers.The Astro-Tech 1.25" diagonal has state-of-the-art 46-layer dielectric mirror coatings for a full 99% reflectivity. This is markedly higher reflectivity than the 88% of a conventional aluminum diagonal or the 96-97% of an easily-tarnished silver diagonal. The result? Extremely faint deep space objects at your scope's performance limits become more visible, changing your viewing from "I guess I see it" to "it's really there!"
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 on deep space objects 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.
Tech Details
| Weight | 5.5 oz. |
|---|---|
| Warranty | 1 year |
Reviews
I got minebefore all the covid crap, so now they might be harder to get?
They are built like a tank and are on the heavy side, so it might way down the cheaper refractors out there. Other then that it's a great dielectric. (Posted on 12/5/2021)
Now the important part, the views. Truly awesome! Looking at the Trapezium in the Orion Nebulae. With the stock diagonal, only three of four stars are visible. The fourth is extremely faint, but not obvious. Swap in this diagonal and all four pop out beautifully!! Great upgrade!! I know for my starter scope this is likely overkill, but it is a solidly built piece that will move up to any upgraded scope my future holds. Awesome. (Posted on 1/4/2020)
I have no qualms about recommending this diagonal for general 1.25" use. It is definitely worth the money and will perform at a high level for many years. (Posted on 8/4/2017)