Celestron - C8-A XLT (CG-5) 8" Optical Tube Assembly (OTA) - 91020XLT

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There are three major components that make up the Star Bright XLT high transmission optical system design

SKU: CEL-91020-XLT
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Product Description

CELESTRON • C8-A XLT (CG-5) 8" Optical Tube Assembly (OTA) - 91020XLT

As the larger cousin to the C6-A XLT, the Celestron C8-A XLT has 843x the light gathering power of the human eye which dwarfs smaller telescopes of this scale. As a Schmidt-Cassegrain optical tube assembly, the corrector plate and primary mirrors render a focal ratio of f/10 which makes these type of catadioptric designs excellent for both visual and imaging as well as being compatible with many optical accessories to adjust its field of view and focal length. With the addition of Celestron's own StarBright XLT coatings, this helps improve light transmission as well, making the C8-A XLT great for planetary and terrestrial observing to wide field observing of deep sky objects. One accessory suggested is the Focal Reducer by Celestron (NOT INCLUDED, SOLD SEPARATELY!) will reduce the focal ratio of this optical tube to an f/6.3 which is much faster for observing and imaging deep sky objects, especially when using large pixels on larger end CCD chips. For the visual astronomer, this optical tube comes packaged with visual accessories including a 25mm eyepiece (for a magnification of 81x), star diagonal, 1.25" visual back, and 6x30 finderscope. The mounting connection is a dovetail rail that connects to the CG-5 mount.


  • 8 inch aperture
  • f/10 focal ratio
  • Schmidt-Cassegrain optical tube
  • StarBright XLT Coatings
  • 6x30 finderscope
  • 1.25" visual back
  • 25mm eyepiece
  • Star Diagonal








Name Celestron - C8-A XLT (CG-5) 8" Optical Tube Assembly (OTA) - 91020XLT
Manufacturer Celestron
Model CEL-91020-XLT
UPC 050234102094
Telescope Aperture 7.1" - 8"
Aperture 203.2 mm (8 in)
Dovetail Compatibility CG-5 Mount
Eyepiece 1 Magnification 81 x
Finderscope 6x30
Focal Length 2032 mm (80 in)
Focal Ratio f/10
Highest Useful Magnification 480 x
Light Gathering Power 843 x
Limiting Stellar Magnitude 14
Lowest Useful Magnification 29 x
Optical Coatings StarBright XLT
Optical Design Schmidt-Cassegrain
Optical Tube Aluminum
Optical Tube Length 17 in (432 mm)
Optical Tube Weight 12.5 lbs (5.67 kg)
Resolution (Dawes) 0.57 arc seconds
Resolution (Rayleigh) 0.69 arc seconds
Secondary Mirror Obstruction 2.5 in (64 mm)
Secondary Mirror Obstruction by Area 9.77%
Secondary Mirror Obstruction by Diameter 31%
Star Diagonal 1.25


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