Tele Vue 3.7mm Ethos-SX

Description 100° & 110° Apparent Field Eyepieces The Tele Vue philosophy (Ethos, if you will) has always been about inspiring "spacewalk" vistas. Now TeleVue brings you the world's first fully-corrected 100° and  110° astronomical eyepieces. Tele Vue is known for its in-house eyepiece and telescope designs by Al Nagler; their latest eyepieces brings new meaning to the term "in-house." The concept for this eyepiece series was proposed by Tele Vue President David Nagler, with performance parameters giving it the fundamental characteristics (the ethos) of a Tele Vue 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 Tele Vue's philosophy of pushing the state of the art, long-time Tele Vue 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, Tele Vue once again broadened the amateur astronomer's perspective on the universe with: 100° of pure Tele Vue quality. The field area of this new eyepiece is more than 50% larger than an 82° field. The Tele Vue 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. TeleVue invited NEAF attendees to take a look and see the universe the way they think it was meant to be experienced, with a field of view incredibly wide and sharp! They were very pleased indeed by the response and validation of their design goals. With 110°, the Ethos-SX has 21% more AFOV area than the 100° Ethos design. This permits a nice 62% power increase from a 6mm Ethos, while retaining 68% of its TFOV. The 3.7mm actually has more TFOV than our 8mm Plössl, 6mm Radian, and 5mm Nagler Type-6! In 1¼" mode, it is parfocal with the wide range of 1¼" Tele Vue Plössls, Panoptics, Radians, Naglers, Nagler Zooms, and 6mm and 8mm Ethos eyepieces. The screw-on 2" adapter (included) is designed to make it parfocal with 13mm and 10mm Ethos when they are used in their 2" modes.  Specifications Model # ETH-03.7 Focal Length (mm) 3.7 Barrel Size (in.) 2" & 1¼" Apparent Field of View (deg.) 110 Eye Relief (mm) 15 Weight (lb / oz) 1.10 / 17.6 Field Stop (mm) 7.04