Finally, at the very corners, the stars are so defocused that they appear as rings instead of pinpoints. But in the first image, as you examine the stars closer and closer to the edge, the stars become larger and less focused. When focused on-axis, both images appear to be sharp in the center. Both images were taken with the same 35 mm chip (42 mm diameter focal plane) camera under the same conditions. The first was taken with a competing coma-free optical design, the second with EdgeHD. Stars will appear out of focus at the edges.Ĭompare the two images of M3 below. This may be acceptable for some visual observing, but when a curved plane is paired with the flat sensor of a digital camera, stars become noticeably out of focus at the edges.ĮdgeHD optics produce a focal plane more than three times flatter than a standard Schmidt-Cassegrain telescope and dramatically flatter than other competing coma-free designs, guaranteeing you visibly sharp stars all the way across the imaging sensor.Ī curved focal plane cannot produce consistent results on a flat CCD chip. The wider the field of view, the more pronounced this defect becomes. Even when focused sharply in the center of the field of view, this curved plane cannot bring stars at the edges into focus. Many optical designs advertise themselves as “astrographs,” but only produce pinpoint stars across a curved focal plane. EdgeHD virtually eliminates both field curvature and off-axis star coma, providing an astrograph-quality system at a fraction of the price of competitors.ĮdgeHD optical tubes are sold separately or paired with our most popular telescope mounts. EdgeHD is an aplanatic flat-field Schmidt optical system designed to produce aberration-free images with pinpoint stars all the way to the edge of the field of view of today’s largest imaging sensors and wide field eyepieces.

Edge hd optical telescope