#Agena astro review full#
However, since the 100° field is so wide that you can't see the full field without having to move your head from side to side to take it all in anyway, vignetting in the conventional sense is not a problem. At a usable eye relief of 15mm, the 13mm Ethos would normally somewhat vignette the field of view for eyeglass wearers. There is a soft rolldown eyecup to shield the eye from ambient light (from a neighbor's security light, for example) and improve the image contrast. The TeleVue Ethos delivers the true field size of a longer focal length (but narrower apparent field) eyepiece, but has the benefits of the higher power and darker sky background that are inherent in a shorter focal length. With a 13mm focal length that evokes that of the original and revolutionary 13mm Nagler eyepiece, the field of this new 100° apparent field Ethos eyepiece is nearly 50% larger in area than the 82° field of a "space-walking" 13mm Nagler. if I were dropped on a desert island tomorrow with the 12-inch scope and only one eyepiece, I'd want it to be the Ethos."
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The on-axis performance is second to none, while the 100° apparent field is unprecedented for an astronomical eyepiece. No meaningful improvements possible." The reviewer commented, "As revolutionary today as the original 13-mm Nagler eyepiece was when it was introduced in 1981, the 13-mm Ethos sets a new standard for wide-field observing.
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Personal Planetariums / Electronic Sky Guides.Focal Reducer and Field Flattener Combos.Equatorial & Altazimuth Accessories & Adapters.