Tele Vue 13.0 Ethos (ETH-13.0)
We have not specifically endorsed the 13mm Ethos for Bino-Vue use because of the large diameter barrel. Even so, we were advised by Mike Harvey at the Winter Star Party (February 2008) that only 1-person in 25 had interpupilary limits with the bino'd Ethos (63.5-mm for the initial production 13mm).
However, since many of our customers have been thrilled with the experience, we have maximized the potential use by narrowing the barrel from 63.5-mm to 62-mm diameter for eyepieces delivered beginning mid-March 2008. While the difference is only 1.5-mm, (or 0.75-mm for pairing a first production unit with current production) we decided to make this small change public, in case you want to give it a try.
TeleVue is known for its in-house eyepiece and telescope designs by Al Nagler; our latest eyepieces brings new meaning to the term "in-house." The concept for this eyepiece series was proposed by TeleVue President David Nagler, with performance parameters giving it the fundamental characteristics (the ethos) of a TeleVue eyepiece: high contrast, comfortable eye relief and full field sharpness. Control of astigmatism, field curvature, lateral color, angular magnification distortion correction, and low pupil sensitivity for daytime use were specified criteria.
Following TeleVue's philosophy of pushing the state of the art, long-time TeleVue employee and optical design protégé Paul Dellechiaie took up the challenge and designed the basic eyepiece form. Under Al's guidance, Paul tweaked his design to fulfill the original goals.
While sharpness is inherent to the optical design, contrast is maximized through the intelligent use of flat finished baffles and ultra low reflectance, high efficiency coatings tuned to the composition of each element.
Introduced at the 2007 Northeast Astronomy Forum, TeleVue once again broadened the amateur astronomer's perspective on the universe with: 100° of pure TeleVue quality. The field area of this new eyepiece is more than 50% larger than an 82° field. The TeleVue Ethos is essentially multiple eyepieces, delivering the true field size of a longer focal length, narrower apparent field eyepiece with the benefits of higher power and darker sky background.
|Barrel Size||2" & 1.25"
|Apparent Field of View||100 degrees|