The best 100-110° eyepieces made.  Superb clarity, color-fidelity, edge-of-field sharpness, light transmission, ultra-low distortion & comfortable 15mm eye relief. Ethos eyepieces have an enormous field with superb contrast. 21 to 3.7mm focal lengths available.

• 100 DEGREE APPARENT FIELD.
• 15MM EYE RELIEF.
• 2" BARREL
• THREADED FOR 2" FILTERS
• RUBBER EYECUP AND CAPS INCLUDED.

Ethos
100° & 110° Apparent Field Eyepieces

The Tele Vue philosophy (Ethos, if you will) has always been about inspiring "spacewalk" vistas. Now we bring you the world's first fully-corrected 100° astronomical eyepiece.

Building on previous 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.

Al Nagler notes:

For reference, the maximum angular magnification distortion of the 13mm Ethos is no more than 1% at any point in the 100° field.

For deep sky viewing of star fields, open and globular clusters, nebulae and galaxies, choose the highest power that frames the subject, so long as the sky background does not reach black, and the atmosphere does not degrade the resolution. The smaller exit pupils permit a darker sky background which achieves greater contrast against the fixed brightness of stars, while the greater magnification reveals more structural details on extended objects. Using eyepieces with larger apparent fields maximizes the viewing experience.

The result is an increase in what I would call the Majesty Factor, the nexus of contrast, power and field.

It's clear that the largest possible apparent field for a given true field yields the most magnification for greater resolution, with a darker sky background for more contrast as a result of the smaller exit pupil. I believe this combination of contrast, power and field causes the typical "wow" reaction — the Majesty Factor. I think Tom Trusock said it most succinctly in his Starfest (Canada) report: "The same true field at higher magnification means that you'll see blacker skies and more detail." Dennis di Cicco in his 5-star review of Ethos in his October 2007 Sky & Telescope review noted something similar: "Observing with the 12-inch scope, I typically bounce between a wide-field eyepiece for star-hopping and a high-power one for detailed views. But the Ethos gave me both. The field was large enough to star-hop, and the magnification was high enough to bring out faint stars and resolve details in galaxies and star clusters."

The 21mm focal length completes the logical set of 21mm/13mm/8mm and nicely juxtaposes the 17mm/10mm/6mm combination. Each step within these two sets approaches a 3x field area gain. The 21mm's effective field stop diameter is 36.2mm, bringing its true field close to the 35mm Panoptic (38.7mm Field Stop diameter). Its true field is also larger than the 26mm Nagler with its 35mm effective field stop diameter. In an f/4 Dobsonian, the exit pupil is just 5.25mm using the 21mm Ethos instead of 8.75mm with a 35mm Panoptic, or 6.5mm with a 26mm Nagler.

TeleVue eyepieces, Barlows, PowerMates, and Paracorr are warranted to be free from manufacturing and workmanship defects for lifetime from the date of purchase.  This warranty applies to the original purchaser and is not transferable.  Defects covered under this warranty are limited to optical coating and cementing, and normal mechanical operation of the product.  The warranty does not include damage caused by mishandling, alteration, normal wear and tear from use, defects of a subjective nature, or coverage for any product not purchased through an authorized TeleVue dealer.
The original owner must complete a warranty registration card and send it to TeleVue Optics for the warranty to be valid, unless state law supersedes.  In such case, or if warranty cards are not submitted, an original dated sales receipt containing the original purchaser's name will serve as proof of purchase for registration.
If your TeleVue eyepiece, Barlow, PowerMate, or Paracorr requires warranty service, please call TeleVue at (845)469-4551 to discuss the problem and obtain a return authorization.  No returns are accepted without prior authorization.
Warranty work will be performed at TeleVue's discretion and may ONLY be performed by TeleVue Optics.  Warranty is void if work is performed on your product by anyone other than TeleVue Optics.  TeleVue Optics reserves the right to assign warranty service to Authorized Service Centers.  In the event a product cannot be serviced, TeleVue will replace the defective product with a current equivalent.  All shipping and insurance charges are excluded from this warranty.
This warranty gives you specific legal rights.  You may be entitled to other rights which vary from state to state.  For warranty coverage outside the United States, contact your local TeleVue authorized dealer for warranty information.  You may have other rights which vary from country to country.
TeleVue does not assume liability for any other warranty, expressed or implied, made by any other entity.


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