Celestron CGEM II 800 EdgeHD Telescopes Whitepaper EdgeHD Optics
Celestron CGEM II 800 EdgeHD Telescopes Manual
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- Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 1
A FLEXIBLE IMAGING PLATFORM AT AN AFFORDABLE PRICE Superior flat-field, coma-free imaging by the Celestron Engineering Team Ver. 04-2013, For release in April 2013. - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 2
outline the construction and testing process for EdgeHD telescopes and provide instructions for placing sensors at the optimum back-focus distance for astroimaging. 1. INTRODUCTION The classic Schmidt-Cassegrain telescope (SCT) manufactured by Celestron served an entire generation of observers and - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 3
EdgeHD Series Edge HD 800 Edge HD 925 Edge HD 1100 Edge HD 1400 FIGURE 1. Celestron's EdgeHD series consists of four aplanatic telescopes with 8-, 9.25-, 11-, 14-inch apertures. The optical design of each instrument has been individually optimized to provide a flat, coma-free focal plane. Each - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 4
telescopic best telescope with power" of the Schmidt corrector plate varies slightly with wavelength. Only in very large apertures or fast SCTs does spherochromism become a problem telescopes at a more consumer-friendly price. As we've already noted, our most important design goal for the new telescope - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 5
out of focus. In comparison, the EdgeHD's spot pattern is tight, concentrated, and remains small from on-axis to the edge of the field. The Celestron EdgeHD 5 - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 6
customer 14-inch aperture classic SCT, coma-free SCT, and EdgeHD. All three are 14-inch aperture telescopes star image viewed at high power will be limited almost " telescope come to focus in front of the on-axis best focus price. Field Curvature Telescope with Field Curvature Flat-Field Telescope - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 7
tolerance. The tube that supports the primary was redesigned an annoyance. In Celestron's SCT and EdgeHD telescopes, we tightened 14 mm off-axis Spot diagrams plotted for 0.0, 3.5, 7, 10.5, and 14 mm off-axis; showing λ = 0.486, 0.546, and 0.656 μm. FIGURE 4. Compare star images formed by a 8-inch - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 8
20mm off-axis; showing λ = 0.486, 0.546, and 0.656μm. FIGURE 5. In a 14-inch coma-free SCT, the smallest off-axis star images lie on the curved focal surface indicated by design. Celestron applies more than forty years of experience in shaping, polishing, and testing astronomical telescope optics to - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 9
and any with defects are discarded. The Johnson/Celestron method for producing the polynomial aspheric curve is based 8-, 9.25-, and 11-inch use N-SK2 and K10 glasses, while the 14-inch uses N-SK2 and N-BALF2 mirror and corrector plate slip into kinematic support jigs, and we place the secondary - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 10
. This close-up image of the Pelican Nebula testifies to the EdgeHD's ability to focus clean, neat, round star images from center to edge. The telescope was a 14-inch EdgeHD on a CGE Pro Mount; the CCD camera was an Apogee U16m. The mage above shows a 21.5×29.8mm section cropped from the original - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 11
an artificial star. With a high-power ocular, a QA Inspector views the • O bserved with a 150 line-pairs-per-inch Ronchi grating, the bands must be straight, uniformly telescope performs to the diffraction limit. 7. FINAL ACCEPTANCE TESTING AND CERTIFICATION Before it can leave Celestron - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 12
a telescope be returned to Celestron for service, we can consult our records to see how well it performed before it left our facility. Once a telescope has to our dealers and customers. To your discerning eye-as an observer with experience-on a night with steady air and good seeing, a properly - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 13
EDGEHD The Celestron EdgeHD was designed and optimized for imaging with astronomical CCD cameras, digital SLR cameras, video astronomy sensors, electronic eyepieces, and webcams. We designed the EdgeHD 800 to deliver the best images 5.25 inches (133.35mm) behind the surface of the telescope's rear - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 14
EdgeHD telescopes. (For more information, see Appendix B.) The Reducer Lens 0.7× for the EdgeHD 1100 is item #94241; for the 14-inch, item equatorial mount, guiding seldom necessary. Of course, the focal length of any EdgeHD telescope can be extended using a Barlow lens such as the Celestron - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 15
telescope, a telescope that provides sharp close-ups as well as high-quality images all the way across a wide, flat field of view. But, consumers want this advanced optical technology at an affordable price. Celestron has designed the EdgeHD to meet customers Telescope Optics: A Comprehensive Manual - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 16
increases in proportion. With a small telescope, seeing plays a smaller role. With the large apertures and long focal lengths of the EdgeHD series, nights of good seeing become particularly valuable. Airy Disk and Seeing Blurs 14-inch 11-inch 9.25-inch 8-inch Airy Superb Excellent Average Disk - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 17
Celestron EdgeHD 800 On-axis, the spots show that the 8-inch EdgeHD is diffractionlimited in both green (for visual observing) and red (for imaging). And because blue rays are strongly concentrated inside the Airy disk, the 8-inch applying flat-field images for the best results. For CCD imaging, we - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 18
EdgeHD 925 Celestron EdgeHD 925 The spot matrix shows that on-axis images are diffraction limited at all three wavelengths, and remain diffraction- 925 is an excellent choice. It offers nearperfect on-axis performance and outstanding images over a full 42mm image circle. 18 I The Celestron EdgeHD - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 19
EdgeHD 1100 Celestron EdgeHD 1100 The 11-inch EdgeHD is optimized to produce its sharpest image circle, and well-defined stars over the full 42mm field. The EdgeHD 1100 is a serious telescope. Its long focal length and large image scale give it the ability to capture stunning wide-field images - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 20
extreme corners of a full-frame 35mm image sensor. We have seen excellent results when the 14-inch EdgeHD is used with a KAF-16803 CCD camera over a 50mm circle. The EdgeHD 1400 is a massive telescope, well suited to a backyard observatory or well-planned away-from-home expeditions. Its long focal - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 21
accessory you can get for an EdgeHD telescope is a focal reducer. Although the dark objects, or just cutting your exposure (and guiding) times down, the focal reducer is a " wide-field eyepiece. The CNC-machined housing easily supports the full weight of your CCD camera or digital Celestron EdgeHD 21 - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 22
EdgeHD 0.7× Reducer Celestron EdgeHD 0.7× Reducer Large T-Adapter T-Ring Adapter Digital SLR EdgeHD 1100 and 1400 5.75 inches 146.05±0.5 mm that the focal reducer's star images are even smaller than those of the telescopes. For observers who wish to pursue faint nebulae in RGB or in narrowband, - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 23
Paquette Imagine the thrill of seeing the first images from your Celestron EdgeHD! A quick glance at the whole image shows that you it's all there, credit to your skill and the design of your EdgeHD telescope. The image shown here is a single monochrome 10-minute exposure taken with an Apogee U16 camera - Celestron CGEM II 800 EdgeHD Telescopes | Whitepaper EdgeHD Optics - Page 24
The Celestron EdgeHD • ©2013 by Celestron • All rights reserved. Torrance, CA 90503 U.S.A. • www.celestron.com
A FLEXIBLE IMAGING PLATFORM
AT AN AFFORDABLE PRICE
Superior flat-field, coma-free imaging
by the Celestron Engineering Team
Ver. 04-2013, For release in April 2013.