Celestron - 14" EdgeHD (Optical Tube)

The EdgeHD optics (Edge High Definition) combine the compact design of a Schmidt-Cassegrain with a significantly improved flat field at the edge of the mirror for imaging. This optical system not only offers the properties of astrographs, but also produces completely undistorted, sharp images right up to the edge of the large visual and photographic field of view. Not only is the coma outside of the optical axis corrected - but also the field curvature!

Many optical systems are promoted as "astrographs", however, they produce the coveted "pinpoint" star image along a curved image plane. On images taken with modern CCD cameras, the result is a noticeable field curvature that increases towards the edge of the image field and becomes stronger the larger the chip is; i.e. the stars remain round, but are blown up into small rings ("donuts") towards the edge.

With the Celestron Edge HD telescopes, this field curvature is corrected right up to the edge in addition to the coma, so that even images taken with large CCD chips are able to remain completely sharp right into the corners of the image field.

This also significantly improves resolution and limiting magnitude compared to competing optical systems with a similar aperture. The Celestron XLT multi-coating also helps the Edge HD optics to achieve a significant increase in performance compared to similar systems on the market.

The EdgeHD optics produces a three-times flatter image in the field plane than a standard Schmidt-Cassegrain. The stars are imaged diffraction-limited across the entire chip of a Nikon D3 or Canon 5D for example.

In addition to the new optics, the mechanics and tube have also been completely redesigned. The new features include:

1. Mirror locks to hold the main mirror in any focus position without exerting pressure on the optical elements. The image always remains stable on the chip, even with long exposure times.
   
2. Ventilation openings behind the main mirror ensure rapid air exchange, so that the optics cool down at a much faster rate. Thanks to an air filter system, no dust gets into the tube either.
   
3. HyperStar Compatible - All EdgeHD tubes allow you to remove the secondary mirror and replace it with the optional HyperStar optics. The result: your standard Celestron EdgeHD telescope becomes a digital Schmidt Design for your CCD or DSLR camera for prime-focus photography at f/2 (C8, C11) and f/1.9 (C14).
   
4. Adapted telecompressors (f/7.5) and Barlow lenses (f/20) are under development.
   
5. Axiom eyepieces - The HD 14 comes with an Axiom eyepiece from Celestron. With a 23mm focal length and 82° field of view, which gives you an impressive combination of magnification and field of view.

Spec:

• Optical design: EdgeHD
  
• Optical coating: Starbright XLT (Fully Multi-Coated)
  
• Telescope aperture: 355.6mm (14")
  
• Resolution (DAWES): 0.33 arc seconds
  
• resolution (RAYLEIGH): 0.39 arc seconds
  
• Focal length: 3910mm
  
• F Ratio: f/11
  
• Secondary mirror obstruction: 11.4cm
  
• Secondary mirror obstruction relative to diameter: 32.00%
  
• Secondary mirror obstruction relative to the surface: 10.00%
  
• Limiting size: 15.3 mag
  
• Highest useful magnification: x840
  
• Light-gathering capacity (compared to the human eye): x2581
  
• Focuser size: 3.3" + 2" SC thread, 1.25"
  
• Tube (material): Aluminum
  
• Tube weight: 21kg
  
• Tube length: 31in (787mm)
  
• Dovetail: CGE (3" Losmandy-Style)

Whats included:

1. Focal length eyepiece: 23mm
   
2. Including accessories: 14" EdgeHD telescope with 3" rail (Losmandy style), 9x50 finder, 2" star diagonal, 1.25" adapter
   
3. Viewfinder: 9x50
   
4. Zenith prism: 2" with 1.25" adapter