The TeleVue Delos eyepieces are 72° field/20mm eye relief versions of TeleVue’s famed 100° to 110° field Ethos eyepieces. As such, they share all of the optical virtues of the Ethos design– full field sharpness, virtually perfect distortion mapping, and color neutrality – simply with a somewhat narrower field (but longer eye relief) than the Ethos. Since each Delos is priced well below the comparable focal length Ethos, you give up a little field of view (but none of the Ethos performance quality) to gain some eye relief and save a lot of money.
Image fidelity is maximized by using a variety of specialized anti-reflection multicoatings that are individually matched to the performance of the specific premium glass types used in the different lenses in each Delos eyepiece. Contrast is enhanced by the use of a new continuously adjustable eyeguard that can be locked in place at any height desired to accommodate your eye and possible eyeglass use.
Since the eye lens in the Delos is a large 35mm in diameter, it is essential to prevent any extraneous light from reflecting off the lens surface and entering your eye. The adjustable height eyeguard and soft rubber fold-down eyecup let you position the eyeguard at the ideal height to suit your preferences and eliminate this possibility. A properly adjusted eyeguard results in a nice increase in perceived contrast. There are reference marks on each eyepiece body for returning its eyeguard to the perfect position for your eyesight should it be moved accidentally or changed for a different observer.
The rubber eyeguard can rotate for use with optional TeleVue Dioptrx astigmatism correcting lenses. The 1,25” Delos eyepieces are parfocal with all other TeleVue 1.25” eyepieces. Each is threaded to accept standard 1.25” eyepiece filters. The relatively narrow body of the Delos make them excellent for use in a binoviewer.