A coma corrector is an optical device used in reflector telescopes to reduce or eliminate coma aberration, a distortion that causes stars near the edges of the field of view to appear elongated or comet-like. It typically consists of lenses or corrective optics placed in the telescope’s optical path, improving image sharpness and clarity across the entire field of view. A field flattener, on the other hand, corrects field curvature and astigmatism, ensuring sharp focus and uniform illumination of the image field, particularly in refractor telescopes and astrographs. Both accessories are valuable for astrophotography, depending on the telescope’s optical design and imaging requirements.
Come for the Scenery, Stay for the Stars