An important benefit of the combination of large apparent field of view and shorter focal length is that for a given field in the sky, higher magnification results in a darker sky background.
Fainter stars become visible and more detail is seen on all deep sky objects.
Ethos provides another big magnification/contrast jump, yielding dramatic views simply not previously possible in any telescope.
With the smaller exit pupil, eyesight limitations are also reduced.

8mm Ethos delivers: 100° apparent field (50% larger in area than 82° Naglers), comfortable eye-relief, accepts DIOPTRX eyesight astigmatism correctors, distortion correction, high contrast and on-axis sharpness for planetary viewing.
It is the “do-it-all” eyepiece perfect for all scopes that can utilize this focal length.

Tele Vue 8mm Ethos Specifications
· Apparent field: 100°
· Focal length: 8mm
· Effective field stop diameter: 13.9mm
· Eye relief: 15mm (accepts DIOPTRX eyesight astigmatism corrector)
· Barrel size: 2"/1¼"
· Black barrel diameter: 53.4mm
· Weight: 0.95 lbs (15.2 oz.)
· Availability: July 2008; orders now being accepted

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Tele Vue 13mm Ethos™

Introduced at Northeast Astronomy Forum 2007
Tele Vue is known for its in-house eyepiece and telescope designs by Al Nagler; our latest eyepiece brings new meaning to the term “in-house.” The concept for this eyepiece was first 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 (technical reference), 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.

At the 2007 Northeast Astronomy Forum, Tele Vue once again broadened the amateur astronomer's perspective on the universe and introduced a new observing experience; 100º of pure Tele Vue quality. With a 13mm focal length evoking the original “Nagler” revolution, the field area of this new eyepiece is more than 50% larger than an 82º 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.

Tele Vue 13mm Ethos Specifications

    * Apparent Field: 100º
    * Focal Length: 13mm
    * Effective Field Stop: 22.3mm
    * Eye Relief: 15mm (accepts DIOPTRX™ eyesight astigmatism corrector)
    * Barrel Size: 2”/1¼”
    * Weight: 1.24lbs.
 

The Ethos has now been shown at NEAF, TSP and RTMC. We thought you’d enjoy sharing in the experience by reading some of the comments written in our “comment” notebook. The following display was created for daytime observation using the Ethos in an NP127is at NEAF and TSP, and an NP101 at RTMC.

The left chart has circles representing field diameters of 50°, 60°, 68°, 82° and 100° with the telescope distance set so that the 100° circle matched the view of the Ethos field-stop. The “crosshairs” are actually small Saturn drawings in 5° increments to illustrate the linear angular-magnification correction. Illustrations of Saturn were placed at the center and edge of the field so contrast and detail (including newsprint dot patterns) could be evaluated.

The chart to the right is an artificial very-rich “star field” made (and conceived) by Rick Scheck in our scope production dept. The bright “star” reflections made a more realistic contrast simulation than simply viewing astronomical pictures and helped to give a “night sky” impression that nicely represented a dense Milky Way star field.

Real night-sky viewing was done two nights at the dark Prude Ranch location of the Texas Star Party using telescopes ranging from our NP127is to the prize winning 12” f/5.5 Newtonian of our own Scott Ewart. Ethos also made its way into various large Dobsonians including those of Barbara Wilson and Larry Mitchell.

At the Riverside Telescope Makers Convention in California, we had two clear, though very bright moonlit nights for evaluation. Using an NP101 and NP127is Ethos treated us to clusters such as M44 and M24.

While all of us at Tele Vue are proud and excited by the response, it’s much more interesting for you to note the recorded comments. On a personal note, I was especially moved by just showing a random star field to a little 10-year-old girl in a group visiting RTMC from Anaheim. Her only words: “Oh my god, it’s beautiful.” It doesn’t get any better than that.

Al Nagler
Kudos to our Paul Dellechiaie, the principal designer of Ethos.

I want to Order the 13mm ETHOS