Al Nagler eagerly pushed Ethos designer Paul Dellechiaie to extend the new 3.7mm focal length to reach 110°, the same field size as the LEM Simulator optics Al designed 45-years ago to train NASA astronauts for lunar landings.
The new Tele Vue Ethos-SX 4.7mm, like its 3.7mm progenitor, is designed and crafted to combine its exceedingly wide field of view with all the contrast, color-rendition, distortion correction and center-to-edge sharpness needed to achieve that natural view.
Compared to a lower power eyepiece with the equivalent TFOV (similar field stop) such as an 11mm Plössl (9.1mm field stop), the greater power – for higher resolution, and smaller exit pupil (for a darker background to enhance contrast) reveals a deep sky experience “even better than you imagined”.
The 4.7mm is a 1¼” format and is parfocal with the wide range of 1¼” Tele Vue eyepieces. 2″ adapter included.
Background
100° & 110° Apparent Field Eyepieces
Tele Vue 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 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.
We invited NEAF attendees to take a look and see the universe the way we think it was meant to be experienced, with a field of view incredibly wide and sharp! We were very pleased indeed by the response and validation of our design goals.
Technical Specifications
Model number: ETH-04.7
Focal Lenght: 4.7 mm
Barrel Size: 2″ & 1.25″
Apparent Field of view: 110°
Eye Relief: 15 mm
Weight: 1.3 lb
Field Stop: 8.94 mm
In the Box
