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Celestron - C11-A XLT (CG-5) 11" Optical Tube Assembly

  • Celestron - C11-A XLT (CG-5) 11" Optical Tube Assembly
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Product Description

Schmidt-Cassegrain optical tubes like the Celestron C11-A XLT have unique features that set them aside from pure reflectors and refractors. Their compact size, usage of both correctors and mirrors, and natural slow focal ratios make these kinds of catadioptric designs great for almost all types of viewing and imaging because they can accommodate many types of accessories that can reduce their focal ratio. First off, Celestron has included StarBright XLT coatings in the C11-A XLT optical tube which improves light transmissions to ensure the highest quality images. Since the focal length is 2800mm resulting in a f/10 focal length, planets will look outstanding but deep sky objects, especially with lower surface brightness’s may not be so apparent. With the optional Focal Reducer (SOLD SEPARATELY), the focal ratio becomes much faster to f/6.3 which is better for deep sky. This is also a benefit for astrophotography because it reduces the risk of blooming, works better with using larger pixel sizes, and overall reduces exposure time length even with the largest CCD sensors available on the market.

For visual astronomers, Celestron has included three useful accessories with the C11-A XLT (CG-5). A 40mm eyepiece is included which will result in a 70x magnification, a visual back is included for 1.25” accessories, a 9x50 finderscope, a star diagonal, and a dovetail rail for mounting to the Celestron CG-5 Advanced Series Mount.

  • Catadioptric Schmidt-Cassegrain design
  • f/10 focal ratio
  • 2800mm focal length
  • StarBright XLT coatings for improved light transmission
  • 40mm eyepiece included
  • 1.25" visual back
  • 9x50 finderscope
  • 1.25" Star Diagonal
  • CG-5 Dovetail rail for mounting



Name Celestron - C11-A XLT (CG-5) 11" Optical Tube Assembly
Manufacturer Celestron
Model CEL-91067-XLT
UPC 050234106795
Aperture 279.4 mm (11 in)
Dovetail Compatibility CG-5 Mount
Eyepiece 1 40 mm (1.57 in)
Finderscope 9x50
Focal Length 2800 mm (110.24 in)
Focal Ratio 10.02
Optical Coatings StarBright / XLT
Optical Design Schmidt-Cassegrain
Optical Tube Aluminum
Optical Tube Length 24 in (609.6 mm)
Optical Tube Weight 27.5 lbs (12.47 kg)
Secondary Mirror Obstruction 3.75 in (95.25 mm)
Secondary Mirror Obstruction by Area 11.6 %
Secondary Mirror Obstruction by Diameter 34.1 %
Star Diagonal 1.25

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