Celestron EdgeHD 11″ Optical Tube Assembly


  • Popular 11″ aperture EdgeHD Telescope
  • 2800mm focal length (f/10 focal ratio)
  • Celestron’s StarBright XLT coatings provide maximum light transmission
  • EdgeHD’s aplanatic, flat field Schmidt-Cassegrain optics result in pinpoint stars to the edge of today’s largest imaging sensors and widest eyepieces for best optical performance
  • Aluminium optical tube with tube vents with mesh filter allows hot air to be released from behind the primary mirror for improved cooling
  • Mirror support knobs hold the mirror in place and reduce image shift during imaging
  • Focal ratio of f/7 with the addition of an optional focal reducer, or ultra-fast Fastar/Hyperstar f/2 imaging with a removable secondary mirror
  • A 9×50 finderscope, wide-angle 23 mm Luminos 2″ eyepiece, 2” mirror diagonal included
EdgeHDStarbright XLT Coatings

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Category: SKU: 91050XLT Tag:


The classic Celestron Schmidt-Cassegrain telescope (SCT) has served an entire generation of observers and astroimagers. Now, with the advent of wide-field and ultra-wide-field eyepieces, large format CCD cameras, and full frame digital SLR cameras, the inherent drawbacks of the classic SCT called for a new optical design – that design is the EdgeHD.

This 11″ aperture model is very popular with serious observers and astroimagers wanting a telescope with large light grasp. The telescope comes complete with a wide-angle 23 mm Luminos 2″ eyepiece, a 2” mirror diagonal and a 9×50 finderscope.

See the Universe in HD
EdgeHD is an aplanatic, flat field Schmidt-Cassegrain telescope that produces 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; it also provides an astrograph-quality flat focal plane all the way to the edge of the field of view.

True Astrograph Quality
Many optical designs that advertise themselves as “astrographs” actually only produce pinpoint stars across a curved focal plane. While this may be acceptable for some visual observing, stars will appear out of focus at the edge when used with the flat chip sensor of a digital camera. EdgeHD optics produce a focal plane more than three-times flatter than a standard Schmidt-Cassegrain telescope and dramatically flatter than competing coma-free designs. This guarantees you visibly sharp stars across some of the largest CCD chips available today. Learn more about EdgeHD technology.

Improved Performance
Superior edge performance not only creates rounder, more pleasing stars, but actually improves the resolution and limiting magnitude when compared to telescopes of equal aperture. With Celestron’s StarBright XLT optical coatings on every surface, EdgeHD optics gives you maximum light throughput across the widest visual and photographic spectrum.

Individually Tested
Every EdgeHD that ships has been tested not only for the surface quality of each optical component, but also with a camera and artificial star to ensure the imaging system meets our rigid quality assurance. This “final acceptance test” confirms the EdgeHD will perform in the field and deliver high-quality astroimages.

Mechanical Features
In addition to the EdgeHD’s optical design, the telescope tube and mechanical features have been redesigned to make sure you get the most from your optics each and every night.

  • Mirror clutches – Flexible tension clutches hold the mirror in place and reduce image shift when taking long exposure astro-images. Once focused, the flexible rods allow the mirror to be held in place without putting any force or pressure on the mirror assembly, keeping the image centred in the eyepiece (or on the sensor).
  • Tube ventilation – Cooling vents located on the rear cell allow hot air to be released from behind the primary mirror. Each vent has an integrated 95-micron micro-mesh filter that is guaranteed to let warm air out without letting dust particles in.
  • Fastar versatility – EdgeHD is the most versatile imaging telescope available today. At its native f/10, you can achieve the image scale necessary to capture the smallest of deep sky objects. Add the optional reducer lens—custom-designed for your size EdgeHD tube—and you can increase your field of view without sacrificing optical performance. A Barlow gives you added power for high-resolution planetary, lunar and solar imaging. All EdgeHD optical tubes are Fastar/Hyperstar-compatible, allowing the secondary mirror to be removed and replaced with a third party lens accessory for ultra-fast f/2 wide field imaging.


EdgeHD Optics Manual

Whitepaper EdgeHD Optics

Optical DesignEdgeHD
Aperture279.4mm (11″)
Focal Length2800mm (110″)
Focal Ratiof/10
Focal Length of Eyepiece 123mm (0.91″)
Magnification of Eyepiece 1122x
Star Diagonal2″ with 1.25″ adaptor
Optical TubeAluminium
Highest Useful Magnification660x
Lowest Useful Magnification40x
Limiting Stellar Magnitude14
Resolution (Rayleigh)0.5 arc seconds
Resolution (Dawes)0.42 arc seconds
Light Gathering Power (Compared to human eye)1593x
Secondary Mirror Obstruction95mm (3.75″)
Secondary Mirror Obstruction by Diameter34%
Secondary Mirror Obstruction by Area12%
Optical CoatingsStarBright XLT
Optical Tube Length610mm (24″)
Optical Tube Diameter312.42mm (12.3″)
Optical Tube Weight28 lbs (13 kg)
DovetailCGE Dovetail Bar

Additional information

Weight17 kg
Celestron Technology



Optical Design