Celestron EdgeHD 8" OTA - CGE Dovetail

EdgeHD Optics: A 42mm Flat-Field Astrograph

The core of the EdgeHD 8" is its aplanatic, flat-field Schmidt-Cassegrain optical system, which produces pinpoint stars across a 42mm image circle. Unlike standard SCTs that project sharp stars onto a curved focal plane, the EdgeHD design delivers a focal plane more than three times flatter, so stars stay sharp to the edge of a flat camera sensor. Celestron optimized the 8" for the central 28mm of its 42mm circle, the size of an APS-C chip.

Superior edge performance not only creates rounder stars but improves resolution and limiting magnitude compared with telescopes of equal aperture.

Imaging at f/10, with a 0.7x Reducer, and at f/2

EdgeHD is a flexible imaging platform.

• Native f/10: At its native 2032mm focal length, the OTA gives the image scale to capture the smallest deep-sky objects.
• Reduced f/7: With the optional EdgeHD 800 0.7x Focal Reducer (#94242), you can increase your field of view without sacrificing optical performance.
• Ultra-Fast f/2: All EdgeHD tubes are Fastar-compatible. The secondary mirror can be removed and replaced with a third-party lens accessory for ultra-fast f/2 wide-field imaging.

Mirror Clutches and Vents in a 14 lb Tube

To support the demands of long-exposure astrophotography, Celestron redesigned the EdgeHD tube. Flexible tension clutches hold the primary mirror in place after focusing, significantly reducing the potential for image shift that can compromise an exposure. Flexible rods hold the mirror without putting force or pressure on the mirror assembly.

Cooling vents on the rear cell let hot air out from behind the primary mirror, and each has an integrated 50-mesh filter that keeps dust out.

843x Light Gathering and 0.57" Resolution

With a light gathering power 843 times that of the human eye, the EdgeHD 8" reaches a limiting stellar magnitude of 14, and StarBright XLT coatings on every surface give maximum light throughput across the visual and photographic spectrum.

Rayleigh resolution is 0.69 arc seconds and Dawes resolution 0.57 arc seconds. Every EdgeHD passes a final acceptance test with a camera and an artificial star before it ships.

Visual Use: 51x Magnification with the Included 40mm Eyepiece

While designed as an astrograph, the EdgeHD 8" is also a superb visual instrument. The package includes a 1.25" star diagonal, a 9x50 finderscope, and a 40mm eyepiece that gives 51x.

The telescope's highest useful magnification is 480x, and the lowest useful magnification is 29x.