About the TeleVue 21mm Ethos Eyepiece - 2"... Tele Vue is known for its in-house telescope eyepiece and TeleVue Telescope designs by Al Nagler; and their latest TeleVue Telescope Eyepiece brings new meaning to the term "in-house." The concept for this TeleVue Telescope Eyepiece series was proposed by Tele Vue President David Nagler, with performance parameters giving it the fundamental characteristics (the ethos) of a TeleVue Telescope 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 and a hallmark of the TeleVue Ethos Eyepiece design. Following Tele Vue'''s philosophy of pushing the state of the art, long-time Tele Vue employee and optical design protege Paul Dellechiaie took up the challenge and designed the basic TeleVue Telescope Eyepiece form. Under Al'''s guidance, Paul tweaked his design of the TeleVue Ethos Eyepiece 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, Tele Vue once again broadened the amateur astronomer'''s perspective on the universe with: 100 degrees of pure Tele Vue quality. The field area of this new eyepiece is more than 50% larger than an 82 degree field. The Tele Vue Ethos Eyepiece is essentially multiple telescope eyepieces, delivering the true field size of a longer focal length, narrower apparent field TeleVue Telescope Eyepiece with the benefits of higher power and darker sky background. Be sure to check out our line of TeleVue Telescopes, TeleVue Telescope Mounts and TeleVue Telescope Accessories. Don'''t forget TeleVue Telescope Eyepieces, TeleVue Dioptrx and TeleVue Eyepiece Filters, too! TeleVue 21mm Ethos Eyepiece - 2" Features... A comfortable 15mm of eye relief and an amazing 100 degree field of view! Contrast is maximized through the intelligent use of flat finished baffles Ultra low reflectance, high efficiency coatings tuned to the composition of each element Delivers the true field size of a longer focal length, narrower apparent field eyepiece with the benefits of higher power and darker sky background Control of astigmatism, field curvature, lateral color, angular magnification distortion correction, and low pupil sensitivity for daytime use High contrast, impressive eye relief and full field sharpness TeleVue 21mm Ethos Eyepiece - 2" Specifications... Focal Length (mm): 21 Barrel Size (in.) : 2" Apparent Field of View (deg.): 100 Eye Relief (mm): 15 Weight (lb / oz): 2.25 / 36.0 Field Stop (mm): 36.2 Warranty: Limited Lifetime TeleVue Product Number: ETH-21.0
