Maximize View Brightness with 99% Dielectric Reflectivity
The Orion 50.8 mm (2 in) Dielectric Mirror Star Diagonal (SKU: OR-08727) is an essential optical upgrade for refractors and Cassegrain telescopes equipped with a 50.8 mm (2 in) focuser. Engineered for observers seeking maximum throughput, this diagonal utilizes state-of-the-art dielectric coatings tested in laboratory environments to achieve an exceptional 99% reflectivity across the visible spectrum.
Precision CNC Aluminum Build & Non-Marring Collars
Unlike standard aluminum-coated mirrors that degrade over time, dielectric coatings consist of multiple thin layers of optical material that are far tougher and impervious to oxidation and environmental wear. The housing is precision-machined from aluminum and anodized for longevity.
The interior features machine-threaded glare baffles that trap stray light, boosting image contrast when observing faint deep-sky nebulae or bright planetary details. Built-in brass compression rings hold your 50.8 mm (2 in) and 31.75 mm (1.25 in) eyepieces firmly without marring or scratching their barrels.
99% Reflectivity
Diffraction-limited optical flatness for ultra-bright celestial views.
Threaded Nosepiece Barrel
The 50.8 mm (2 in) nosepiece barrel features standard filter threads. Attach your 50.8 mm (2 in) light pollution, UHC, or lunar filter directly to the diagonal nosepiece and swap eyepieces without having to remove and reattach the filter every time.
Step-Down Adapter Included
Includes a precision 50.8 mm to 31.75 mm (2 in to 1.25 in) step-down adapter, ensuring seamless compatibility with both major eyepiece barrel standards.
Technical Specifications
| Parameter | Specification Details |
|---|---|
| Brand & Model | Orion 50.8 mm (2 in) Dielectric Mirror Star Diagonal |
| SKU / Part Number | OR-08727 / OR-99376 |
| Diagonal Angle | 90 Degrees |
| Barrel Diameter | 50.8 mm (2 in) |
| Mirror Coatings | Dielectric Coating (99% Reflectivity) |
| Optical Quality | Diffraction-Limited |
| Housing Material | Machined & Anodized Aluminum with Internal Baffles |
| Eyepiece Retention | Brass Non-Marring Compression Rings (2 in & 1.25 in) |
| Step-Down Adapter | Included: 50.8 mm to 31.75 mm (2 in to 1.25 in) |
| Filter Threads | Yes (Threaded for standard 50.8 mm / 2 in filters) |
| Inward Focus Travel Requirement | ~110 mm (~11 cm / ~4.3 in) inward focus travel |
| User Skill Level | Intermediate / Advanced |
| Weight | 481.95 g / 0.48 kg (17 oz) |
What's in the Box
- 1x Orion 50.8 mm (2 in) Dielectric Mirror Star Diagonal
- 1x Step-down Adapter 50.8 mm to 31.75 mm (2 in to 1.25 in) with Brass Compression Ring
- 2x Protective Dust Caps (Nosepiece & Eyepiece Collar)
Telescope Compatibility & Usage Guidelines
| Brand | Orion |