The Celestron Edge HD 800 takes the Schmidt-Cassegrain (SCT) system and minimizes the coma at the edge of the field of view, making the optics suitable for very professional high-end astrophotography. When coma occurs, stars at the edge of the field of view don't appear as razor sharp as those in the center. The EdgeHD optical tube assembly ensures that high definition pinpointed images are not only in the center, but at the very edges as well. Aplanatic Schmidt-Cassegrain optical system. This compound, or catadioptric, light-path employs a combination of mirrors and lenses that offer a large, high-resolution aperture, a shorter tube length, and enhanced portability. Since this is a catadioptric design, therefore using mirrors and corrective plates, taking aspects from both reflectors and refractors, telescopes like the Celestron Edge HD 800 naturally result in having a slower focal ratio of f/10, which is excellent for viewing or imaging planets or any other objects with high surface brightnesses at smaller fields of view. Celestron's built in Fastar system uses a removable secondary mirror to transform the optical tube into a f/2 focal ratio which is outstanding for deep sky observing! With a fast focal ratio, this 8" optical tube assembly can accommodate very large CCD chips because it allows for bigger pixel size without as much chance of blooming and allows much shorter exposure times.

• The Celestron 8" EdgeHD Optical Tube Assembly is the smallest of the series, striking the right balance between affordability, lightweight and still getting the EdgeHD optical and imaging benefits!
• With Celestron's well known and renowned EdgeHD optics, flat curvature provides pinpoint stars across the entire field of view making it excellent for producing high resolution images!
• With a slower focal ratio of f/10 due to it using both mirrors and corrective plates, it is excellent for planetary imaging. When using the Fastar system by removing the secondary mirror and replacing it with another lens accessory, it becomes an f/2 making it remarkable for deep sky even for the large CCD chips!
• The versatile design of the Celestron Edge HD 800 accommodates 3 focal ratios: native f/10, f/7 with the addition of a focal reducer, or ultra-fast f/2 imaging with a removable secondary mirror and third-party accessories.
• Aluminum optical tube with tube vents featuring an integrated 95-micron mesh filter allows hot air to be released from behind the primary mirror. Mirror support knobs hold the mirror in place and reduce image shift during imaging.