Taking design inspiration from the venerable Ethos line but with a narrower field of view to provide users with a long more comfortable eye relief, the Tele Vue Delos 12mm Eyepiece was designed for easy long-duration lunar and planetary observation. Index-matched anti-reflective multi-coatings applied to the glass lenses were engineered specifically to maximize light transmission, which produces sharp, bright, high-contrast, and color-faithful images across the entire spacious 72° apparent field of view. Its adjustable-height rubber eyecup helps to further enhance contrast by preventing stray light from entering the user's peripheral vision, which can interfere with the image seen through the ocular. The eyepiece is offered with a 1.25" diameter barrel for compatibility with a wide variety of filters and accessories, and is parfocal with Tele Vue Group B eyepieces so no refocusing is required when switching between eyepieces within the group.