New optical design
The Celestron EdgeHD 11" SC telescope combines the compact design of Schmidt-Cassegrain telescopes with significantly improved image quality at the edge of the field of view. This optical system not only offers the features of an astrograph, but also produces completely distortion-free, sharp images all the way to the edge of the visual and photographic field of view. It corrects coma not only off-axis—as with other so-called “coma-free” optical systems on the market—but also flattens the image plane.
The difference
Many optical systems are marketed as “astrographs”; however, they produce the desired pinpoint star images along a curved image plane. When using modern CCD cameras, this results in noticeable field curvature that increases towards the edge of the field, becoming more pronounced with larger CCD sensors. Although the stars remain round, they are slightly out of focus.
With Celestron EdgeHD telescopes, this curvature is corrected in addition to coma, all the way to the edge of the field of view, ensuring that images captured even with large CCD sensors remain completely sharp and evenly focused across the entire chip—right into the corners.
The new optical system improves resolution compared with competing optical systems of similar aperture. EdgeHD optics also feature Celestron XLT multilayered coatings, delivering significantly better performance than similar systems available on the market.
Celestron EdgeHD telescopes are Fastar-compatible, meaning that—similarly to conventional SC optical tubes—the secondary mirror can be removed and a CCD camera can be fitted directly in its place using a suitable adapter. In this configuration, the instrument operates as an ultra-fast f/2 system. Naturally, standard SC accessories can also be easily attached to the optical tube. Filtered ventilation openings on the telescope tube help achieve faster thermal equalisation. The annoying characteristic of catadioptric telescopes, mirror shift during changes of direction, has been minimised through a mechanically more stable focusing system. The practical, robust handle on the tube also deserves special mention.
The Celestron Advanced VX mount is a highly portable mount optimised for astrophotography; for further information, please visit the product page.
