Celestron EdgeHD 800 8" Aplanatic Schmidt-Cassegrain Optical Tube

A flat-field 8-inch astrograph that a mid-size mount can carry

The Celestron EdgeHD 8" Optical Tube Assembly (CGE dovetail) is a 203mm (8") f/10 aplanatic Schmidt-Cassegrain for deep-sky imaging, planetary imaging and high-power visual observing. It's the lightest EdgeHD, which makes it the easiest way into a flat-field SCT without stepping up to a heavy mount. This is the optical tube only, on a Losmandy-style CGE dovetail bar. It comes with a 9x50 finderscope, a 1.25" star diagonal and a 40mm Plössl eyepiece.

Key specs: 203mm (8") aperture · 2032mm focal length · f/10 (f/7 with the 0.7x reducer) · EdgeHD aplanatic flat-field optics · StarBright XLT coatings · 432mm (17") long · 6.35kg (14 lb) · CGE dovetail · Fastar compatible

What you can see and image

• Galaxies: the Whirlpool Galaxy (M51), the Sombrero (M104), the Leo Triplet and M81/M82 in Ursa Major.
• Planetary nebulae: the Ring Nebula (M57), the Dumbbell (M27), the Cat's Eye (NGC 6543) and the Owl Nebula (M97).
• Globular clusters: M13, M92 and M3.
• Planets and the Moon: Jupiter, Saturn and Mars at high power, or with a planetary camera such as the ZWO ASI585MC.
• Visual observing: the included 40mm eyepiece gives 51x for finding objects and viewing large clusters.

How the EdgeHD is different from a standard SCT

A regular Schmidt-Cassegrain has a curved focal plane and some coma, so stars near the edge of a camera sensor go soft. The EdgeHD adds corrector lenses near the back of the tube that flatten the field and remove the coma. Celestron tests every EdgeHD with a camera and an artificial star before it ships.

• Reducer: the 0.7x EdgeHD 800 reducer takes you to 1422mm at f/7, a 43% wider field with half the exposure time, and gives 105mm of back focus for filter wheels and off-axis guiders.
• Mirror locks: once focused, the locks hold the primary mirror steady as the telescope tracks.
• Cooling vents: mesh-filtered vents in the rear cell let warm air out from behind the mirror while keeping dust out.

Field of view with an APS-C camera: with a ZWO ASI2600MC Pro (23.5 × 15.7mm sensor), the EdgeHD 8 covers about 40 × 27 arcminutes at f/10 (0.38″ per pixel). With the 0.7x reducer that grows to about 57 × 38 arcminutes (0.55″ per pixel), a good match for typical seeing.

What to add for the best results

• A mount (required): the tube weighs 14 lb before a camera. The ZWO AM5N (33 lb without a counterweight), the Celestron Advanced VX (30 lb) and the Celestron CGEM II (40 lb) all take its CGE dovetail.
• Celestron 0.7x Reducer for EdgeHD 800: f/7 and a wider field, the setting most EdgeHD 8 owners image at.
• T-Adapter for EdgeHD 8: threads onto the rear cell to attach a camera at prime focus.
• A camera: the ZWO ASI2600MC Pro for deep-sky color, or the ASI585MC for planets and the Moon.
• Guiding: an off-axis guider such as the ZWO OAG, or the StarSense Autoguider V2 on Celestron mounts.
• Dew control: the Dew Shield DX for 6"–8" or the aluminum dew shield and cap, plus an 8" Celestron dew heater ring.
• EclipSmart Solar Filter for 8" SCT / EdgeHD: for safe white-light views of sunspots. Never point the telescope at the Sun without it.

EdgeHD 8 vs. EdgeHD 9.25 vs. C9.25

See all Celestron EdgeHD telescopes and Schmidt-Cassegrain telescopes.

What's in the box

• EdgeHD 8" f/10 optical tube with StarBright XLT coatings
• CGE (Losmandy-style) dovetail bar
• 9x50 finderscope with bracket
• 1.25" star diagonal
• 40mm Plössl 1.25" eyepiece (51x)

The mount, reducer, T-adapter, camera and dew control are sold separately.

Celestron EdgeHD 8 FAQ

Is the EdgeHD 8 good for beginners?

For visual observing, yes, once it's on a good mount. For imaging, it's a step up: at 2032mm you need accurate polar alignment and autoguiding. Many people start with a small refractor and add an EdgeHD 8 for galaxies and planetary nebulae. We're happy to help you plan the setup in our Denver store.

What mount do I need?

For imaging, the ZWO AM5N, Celestron Advanced VX or Celestron CGEM II. The included dovetail is the wide CGE (Losmandy-style) type, which all three accept. On a strain wave mount like the AM5N, a counterweight helps balance the SCT.

EdgeHD 8 or EdgeHD 9.25?

The 9.25 has more aperture and focal length and comes with a 2" diagonal and a 23mm Luminos eyepiece, but it weighs 7 lb more and needs a bigger mount. The EdgeHD 8 is easier to carry and mount, and its f/7 reducer gives a wider field for larger galaxies.

Can I see Saturn and Jupiter?

Yes. An 8" SCT shows Saturn's rings and the Cassini Division and Jupiter's cloud belts in steady air. Add a shorter eyepiece or a Barlow for 150–250x.

Does it work with HyperStar?

Yes. Every EdgeHD is Fastar compatible, so the secondary mirror can be swapped for a third-party f/2 lens.

Specifications