Sky-Watcher 90° 2" Dielectric Star Diagonal

The Sky-Watcher 90° 2" Dielectric Star Diagonal is a premium, high-performance accessory engineered specifically for high-end telescopes equipped with a 2" focuser. Its standout feature is a dielectric-coated mirror that achieves a remarkable 99% reflectivity, delivering exceptionally bright images with virtually no loss of luminosity. Furthermore, the mirror’s high optical correction of 1/10 lambda ensures that the resolution and contrast of your telescope's objective are fully preserved, allowing for breathtakingly sharp views of celestial wonders.

Constructed with a solid and elegant CNC-machined body, this diagonal is built for both durability and precision. The telescope-side connection is conveniently threaded to accept 2" filters, while the eyepiece side utilizes a brass compression ring to securely hold your optics without scratching or damaging the barrels. For added versatility, the package includes a 2" to 1.25" adapter, also equipped with a brass compression ring, allowing you to use your entire collection of eyepieces with this top-tier optical component.

Product Features in Detail

Ultra-Bright Dielectric Coatings

Standard mirrors lose several percent of light with every reflection. This diagonal uses advanced dielectric layers to ensure that almost every photon gathered by your telescope reaches your eye, which is essential for observing faint nebulae and distant galaxies.

Diffraction-Limited Surface Accuracy

With a surface flat to 1/10 of a wavelength of light, this mirror is precise enough to handle the highest magnifications. It ensures that the wavefront remains undistorted, preserving the pinpoint sharpness of stars and the fine detail on planetary surfaces.

Non-Marring Accessory Security

Unlike traditional set-screws that can gouge and scratch expensive eyepieces, the internal brass compression rings apply even pressure. This keeps your eyepiece perfectly centered on the optical axis while keeping the barrels in mint condition.

Solid CNC Craftsmanship

The housing is carved from a solid block of aluminum using computer-controlled machining. This results in a diagonal that is not only aesthetically beautiful but also strong enough to support the heaviest 2" wide-angle eyepieces without sagging.

Convenient Filter Integration

By threading your 2" filters directly onto the nosepiece of the diagonal, you can swap eyepieces without having to move the filter each time. This is a massive time-saver for visual observers who use UHC or OIII filters frequently.

Versatile Two-in-One Solution

This diagonal bridges the gap between different eyepiece standards. Whether you are using a massive 2" wide-field eyepiece for scanning the Milky Way or a high-power 1.25" planetary eyepiece, the included precision adapter makes the transition seamless.