Please note: This text was taken directly from the manufacturer.
With most eyepieces, stars look sharp in the center of the field of view, but start getting fuzzy and flared toward the edge. To get better, "flat-field" performance, you have to pay big bucks for exotic ocular designs. Not anymore. Orion Edge-On eyepieces deliver remarkably flat fields -- pinpoint-sharp stars from the center to the edge of the viewing circle. And best of all, their price won't flatten your wallet! You'll be as amazed by the value as you are by the views. Their 5- or 6-element optical design eliminates field curvature for distortion-free images. And Edge-Ons are parfocal, so you can change eyepieces without refocusing. With their big eye lenses, fully multi-coated lens elements, long eye relief, generous fields of view, twist-up eyeguards, and 1.25" barrels threaded for filters, Edge-On eyepieces have the features and quality you'll appreciate. Get the eyepieces with a flat-field edge -- Orion Edge-Ons!
