The Celestron EdgeHD 925 is an aplanatic flat field Schmidt-Cassegrain which provides aberration-free images across a wide field of view. A true astrograph, the EdgeHD 925 provides a 42mm image circle, making it suitable for full frame sensors.
Celestron's EdgeHD series combines the strengths of Schmidt-Cassegrains with imaging performance of modern Corrected Dall-Kirkham designs, all in an affordable package. The classic SCT is well corrected on-axis but suffers from coma and field curvature, making them unsuitable for deep sky imaging. By adding a two-element corrector lens and optimizing the overall optical design, the EdgeHD solves these problems while keeping costs low for a full frame-corrected instrument. The EdgeHD series includes Celestron's StarBright XLT optical coatings on each surface, giving maximum light transmission across the visual and photographic spectrum between 400 - 750nm.
In addition to the optimized optical design, the EdgeHD includes flexible tension mirror clutches which reduce image shift over long exposures. This allows the mirror to be held securely in place without putting additional force or pressure on the mirror assembly. Filtered cooling vents on the rear cell let hot air to be expelled from behind the primary mirror.
The EdgeHD is an incredibly versatile instrument, with a 0.7x reducer available separately and Fastar/Hyperstar compatibility for super-fast imaging at f/2.
Every EdgeHD is tested in-house by Celestron to ensure its high optical performance and the surface quality of each optical surface.
