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Celestron - EdgeHD 8" Optical Tube Assembly (CG5)


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Manufactured by: Celestron


CELESTRON - EdgeHD XLT 8" Optical Tube Assembly (91031-XLT)

To obtain good images in astrophotography, the first step is pretty simple. To have as little optical defects as possible when taking exposures. While Schmidt-Cassegrain optical tubes do provide great astrophotography instruments, the coma that results on the edge of the field of view that cause distortion of stars can become a problem. With Celestron's EdgeHD, stars will appear pinpoint throughout the entire image. This creates stunning astrophotography instruments for both terrestrial and planetary observing as well as deep sky observing. Although catadioptric designs such as the Edge800 HD are quite wide and not very long in dimensions, they naturally have a slower focal ratio. In the case of the Edge800 optical tube assembly, there is a focal ratio of f/10, making this instrument by default excellent for smaller field of view high brightness objects. Deep sky imaging and faster imaging is also possible with Celestron's fastar system with the removable secondary mirror to create a remarkable fast f/2 focal ratio! Since deep sky observing in general is better when using larger pixels, the exposure time is reduced and blooming is less likely when using instruments with a very fast focal ratio. This makes imaging easier when larger CCD chips. Includes dovetail bar for Celestron CG5 mount.


  • 8" aperture
  • StarBright XLT coatings for improved light transmission
  • EdgeHD to eliminate coma even at the edge of the field of view
  • Focal ratio of f/10
  • Fastar focal ratio of f/2
  • Great for astrophotography!
  • 40mm Plossl Eyepiece included
  • 1.25" Star Diagonal
  • 1.25" Visual Back
  • Dovetail slide bar for CG-5 mount











Product Series

SEE THE UNIVERSE IN HD Introducing Celestron's New Aplanatic Schmidt Telescope Design! visibly Sharper images Superior performance. Enhanced Mechanical features fastar Compatible

EdgeHD is an aplanatic Schmidt telescope designed to produce aberration-free images across a wide visual and photographic field of view. The optical system was designed to reduce more than just off-axis star coma, but also to give an astrograph quality flat focal plane all the way to the edge of the field of view.



Additional Information

Name Celestron - EdgeHD 8" Optical Tube Assembly (CG5)
Manufacturer Celestron
Model CEL-91031-XLT
Manufacturer Part No CEL-91031-XLT
Aperture 8 in (203 mm)
Dovetail Compatibility CG-5 Mount
Eyepiece 1 40
Finderscope 9x50
Focal Length 2032 mm (80 in)
Optical Coatings StarBright XLT
Optical Design EdgeHD
Optical Tube Aluminum
Optical Tube Length 17 in
Secondary Mirror Obstruction 2.7 in (69 mm)
Star Diagonal 1.25