The Orion 9mm Expanse Eyepiece features 66° apparent field of view. It shows objects like the Andromeda Galaxy, the Double Cluster, or the star clouds in Sagittarius in one sweep. Expanse oculars have big eye lenses and great eye relief (13mm to 17mm). Eyeglass wearers can view the entire field without removing their glasses.
All eyepiece elements are fully coated, with the outer lens multi-coated for additional light transmission. Each 1.25" aluminum barrel is threaded for filters and internally blackened to eliminate internal scattering. And their fold-down rubber eyeguards enhance contrast by blocking stray light. The expanse eyepieces provides a super wide field of view and superior optical performance.