Related Manuals for Celestron EDGEHD
Summary of Contents for Celestron EDGEHD
- 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.
- Page 2 SCT called for a For more than forty years, the SCT satisfied the needs of new design. The EdgeHD is that new design. The EdgeHD of- visual observers and astrophotographers. Its performance fers clean, diffraction-limited images for high power observation resulted from a blend of smooth spherical surfaces and of the planets and the Moon.
- Page 3 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 EdgeHD optic produces sharp images to the edge of the view with minimal vignetting.
- Page 4 Furthermore, because it retains key elements of the classic SCT, the EdgeHD design is compatible with the popular Starizona Hyperstar accessory. The Celestron EdgeHD...
- Page 5 The EdgeHD clearly outperforms the other optical systems. The classic SCT shows prominent coma. The “coma-free” SCT is indeed free of coma, but field curvature causes its off-axis images to become diffuse and 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.
- Page 6 “wings” of red light, lie inside a circle only to the very edge. (Indeed, the name EdgeHD derives from our 50µm in diameter, the images in the EdgeHD have proven to be edge-of-field requirements.) quite acceptable in the very corners of the image captured by a full-frame digital SLR camera.
- Page 7 Compare star images formed by a 8-inch coma-free SCT with those formed by an EdgeHD. The sharpest star images in the coma-free SCT follow the gray curve, coming to focus approximately 0.6mm in front of the focal plane. In the EdgeHD, small, tight star images are focused at the focal plane across the field of view, meaning that your images will be crisp and sharp to the very edge.
- Page 8 5. In a 14-inch coma-free SCT, the smallest off-axis star images lie on the curved focal surface indicated by the gray line. Since CCD or digital SLR camera sensors are flat, so star images at the edge of the field will be enlarged. In the aplanatic EdgeHD design, the smallest off-axis images lie on a flat surface.
- Page 9 Celestron grinds the front surface of scattered light. In addition, the intra- and extra-focal diffraction...
- Page 10 8. After all the testing is done, the ultimate test is the night sky. 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;...
- Page 11 After striking the parabolic mirror, the parallel rays of light travel down the optical bench to the EdgeHD under test, through the FIGURE 10. We test all of our primary mirrors on an optical telescope, to a full-frame format digital SLR camera placed at bench by means of laser interferometry.
- Page 12 The EdgeHD reveals faint nebular details as fine as the sky quality at the observing site will allow.
- Page 13 55mm.) refractor mounted piggyback on your EdgeHD telescope. You will need a dovetail bar attached to the EdgeHD tube. Celestron The T-mount system also makes spacing an astronomical CCD offers an 80mm guide telescope package (item #52309) to camera easy.
- Page 14 EdgeHD telescope. For the sharpest wide-field imaging, your goal is to place the sensor 5.25 inches behind the rear flange of the EdgeHD 800, or 5.75 inches behind the rear flange of the EdgeHD 925, 1100, and1400.
- Page 15 Celestron has designed the EdgeHD to meet customers’ needs. The EdgeHD is not only coma-free, but it also provides a flat field so that stars are sharp to the very edge of the field of view.
- Page 16 • The guiding accuracy during exposure To aid astroimagers, this Appendix presents a spot matrix plot for each of the telescopes in the EdgeHD series. To determine the size of the images that you observe in your exposures, these must be compounded with the other factors that affect your images.
- Page 17 Celestron EdgeHD 800 Celestron EdgeHD 800 On-axis, the spots show that the 8-inch EdgeHD is diffraction- Although for bright subjects this minor falloff would pass limited in both green (for visual observing) and red (for imaging). unnoticed, for imaging faint objects we recommend making and And because blue rays are strongly concentrated inside the applying flat-field images for the best results.
- Page 18 The size of the off-axis blue and red spots remain For full-field imaging on a tight budget, the EdgeHD 925 is an nicely balanced. excellent choice. It offers nearperfect on-axis performance and On a night of average seeing, stars will display a FWHM of outstanding images over a full 42mm image circle.
- Page 19 42mm field. 16mm, then falls slowly to 83% at the very edge of a 42mm The EdgeHD 1100 is a serious telescope. Its long focal length image circle. and large image scale give it the ability to capture stunning...
- Page 20 We have seen excellent results when the green light, and the well balanced spherochromatism in the 14-inch EdgeHD is used with a KAF-16803 CCD camera over blue and red. These spots are far better than spots from a fine a 50mm circle.
- Page 21 The EdgeHD 0.7x Focal Reducer shortens the field curvature, and suffered from severe vignetting. But the focal ratio of the of the EdgeHD 1400, 1100 and 800 while days of film and ersatz focal reducers are over. The modern maintaining sharp images across the full field. This enables CCD...
- Page 22 Plotted at the same scale as those for the halves the necessary exposure time with no sacrifice in resolution EdgeHD, the spots demonstrate that the focal reducer’s star or image quality. images are even smaller than those of the telescopes.
- Page 23 Image by André Paquette Imagine the thrill of seeing the first images from your Celestron EdgeHD! A quick glance at the whole image shows that you have captured your target’s faint outer extensions. Across the field, from one side to the other, star images are sharp, crisp, and round. As you process your image, fine details in the target object reveal themselves.
- Page 24 The Celestron EdgeHD • ©2013 by Celestron • All rights reserved. Torrance, CA 90503 U.S.A. • www.celestron.com...