The Celestron EdgeHD 8" 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 characteristics of an astrograph, but also produces perfectly sharp, distortion-free images all the way to the edge of the visual and photographic field of view. It corrects not only off-axis coma—as do other so-called “coma-free” optical systems available on the market—but also field curvature.
The difference
Many optical systems are marketed as “astrographs”; however, they produce the desired pinpoint star images along a curved image plane. With images taken using modern CCD cameras, the result is 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, both coma and field curvature are corrected right to the edge of the field of view, ensuring that even images taken with large CCD sensors remain perfectly sharp and evenly focused across the entire sensor, including 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 comparable systems 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 focal ratio system. Naturally, commonly used SC accessories can also be easily attached to the optical tube. Filtered ventilation openings on the telescope tube promote faster thermal equalization. The annoying characteristic of catadioptric telescopes, mirror shift during changes of direction, has been minimized with a mechanically more stable focusing system. The practical, sturdy handle on the optical tube also deserves special mention.
The Celestron Advanced VX mount is a highly portable mount optimized for astrophotography; for further information, please refer to the product page.
