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Celestron - C6-A-XLT (CG-5) 6" Optical Tube Assembly


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Manufactured by: Celestron


CELESTRON •  C6-A-XLT  6" Optical Tube Assembly (OTA)   •  91010-XLT

The Celestron Fastar capable C6-A XLT is a 6” Schmidt-Cassegrain optical tube(only) has a light gathering power of 459x compared to the human eye. This is outstanding even when you factor in Celestron adding in its own StarBright XLT coatings for improvements to light transmissions. With a focal length of f/10,  it is a mid-range for Schmidt-Cassegrain designs. Since it is a “hybrid” between both reflectors and refractors, using a correcting plate as well as mirrors, it is devoid of many of the chromatic aberration found in normal refractors using primary lenses. While the focal ratio is quite slow for deeps sky observing, using the optional Focal Reducer (SOLD SEPARATELY) will transform this telescope into a f/6.3, making it a much faster instrument and more suitable for larger sensors or astrophotography with larger pixels. However, even without this add on, planetary and terrestrial objects will look outstanding. Visual observers will have a few accessories already included to enjoy using. This will include a 25mm eyepiece that will result in a 60x magnification, star diagonal, visual back for 1.25” accessories, and a 6x30 finderscope. For the C6-A XLT optical tube, there is a dovetail rail that is designed to be compatible to mount to several different mount types..


  • Remarkable 459x light gathering power!
  • Includes Celestron's StarBright XLT Coatings
  • Neutral focal ratio of f/10
  • Schmidt-Cassegrain Design
  • 25mm eyepiece
  • Star Diagonal
  • Finderscope
  • 1.25" Visual Back
  • C6-A XLT dovetail rail for mounting
  • Fastar Capable







Product Series

Celestron’s excellent Schmidt-Cassegrain telescopes are compact and portable and represent the best all-purpose design for a wide variety of uses from terrestrial and deep sky viewing to astrophotography.

Additional Information

Name Celestron - C6-A-XLT (CG-5) 6" Optical Tube Assembly
Manufacturer Celestron
Model 91010-XLT
Angular Field of View .83°
Aperture 150 mm (5.91 in)
Dovetail Compatibility CG-5 Mount
Eyepiece 1 25 mm (0.98 in)
Fastar Compatible No
Finderscope 6x30
Focal Length 1500 mm (59.06 in)
Focal Ratio 10
Magnification 1 60 x
Optical Tube Aluminum - black
Optical Tube Length 16 in (406.4 mm)
Optical Tube Weight 10 lbs (4.54 kg)
Resolution (Dawes) 0.77 arcsec
Resolution (Rayleigh) 0.93 arcsec
Secondary Mirror Obstruction 2.2 in (55.88 mm)
Secondary Mirror Obstruction by Area 13.9 %
Secondary Mirror Obstruction by Diameter 37.3 %
Star Diagonal 1.25