The Tele Vue philosophy (ethos, if you will) has always been about inspiring "spacewalk" vistas by creating both the finest "rich field" refractors and wide angle eyepieces. With their minimum 100-deg apparent field of view, full-field sharpness, and exceptionally high contrast, the Ethos eyepiece line is another step in that direction.
All Tele Vue Ethos eyepieces have proprietary tuned full multi-coatings, blackened lens edges, high index glasses, fold-down eyeguards, rubber grip rings, cover for the eyeguard, an undercut in the barrel for extra locking security, and filter threads. All Tele Vue eyepiece lines are proprietary, in-house designs manufactured to their specifications and tolerances. Every eyepiece is individually tested at Tele Vue to ensure it meets high optical and cosmetic standards.
Ethos Series Development History
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.
Jul 5, 2015
Excellent Field of ViewPros:
Quality Lenses,Easy to Use,Accurate,Strong ConstructionCons:
The Field of View on this Eyepiece is extraordinary. 13mm is the best size to get because if you want to have more magnification you can screw on a Barlow and if you want less, then just use the Celestron reducer. I have found that using the William Optics 2" diagonal, that screws directly to the back of the 8SE, with this eyepiece, and you'll get the brightest and clearest views.
This review was provided courtesy of AgenaAstro.com
wrose New Member
- Skill Level
- Time with Product
Nov 20, 2007
- User Notes:
TV Ethos - 13mm, 100° FOVPros:
Expansive FOV; Excellent image quality, as good as the NaglersCons:
$$$; Needs a Paracorr when used with a DOBComments:
I've been using a 13mm Ethos for a few months now at home and a couple high altitude dark sites in the Colorado and Arizona mountains. Primarily I've used the Ethos with an AP Traveler (4" APO), TV NP-127, AP 152, C9.25, and a 12.5" StarMaster. The Ethos has also been dropped in a Tak FC-60E, Vixen 90mm MCT, and Meade EXT-125 for several viewing sessions.
Under mag 4 or better skies, the Ethos was amazing in every scope I've tried it in. The expansive view of the Ethos is outstanding. It's a definite breakthrough in wide angle viewing. Being fortunate enough to have a dozen scopes to try the Ethos in helped sort out optical combination issues I've read about in several posts and write-ups. I've found a Paracorr eliminates any issues with the faster Newts and the field curvature some people talk about is very scope dependent. The Ethos used with the AP 152 StarFire and NP-127 exhibits very little field curvature (FC), if any. Drop it in the AP Traveler and there's a slight, but noticeable, amount of FC on the outer edge. It's not enough to be bothersome but if you look for it, you'll notice it. While the Ethos seems almost as big as the diminutive Tak FC-60E itself, the view through the pair is nothing short of spectacular for a 60mm scope. Even a brief glimpse in a couple of 80mm f/5 rich field refractors (C80 & Generic 80mm Synta) was very impressive. Using the Ethos in the 3 1/2" & 5" MCTs was a delight and in the C9.25 SCT, the Ethos is exceptional.
Initially the Ethos was compared with a 13mmT1, 13mmT6, and 12mmT4 Nagler in an AP Traveler & 12.5" StarMaster. Something immediately noticed about the Ethos is the eye point seems more critical than the Naglers. Most old timers get used to a 'tight' eye position with some eyepieces but that's generally with eyepieces that have relatively short eye relief. While doing the initial daylight comparisons, I noted the eye relief of the Ethos is marginally better than the 13mm T6 Nagler but the eye position is more critical to obtain a full, clear view. During these daylight observations I noticed even a slight sideways shift in eye point causes a very slight graying, central spot, kidney bean effect. Any further movement off eye point causes actual kidney bean and blackout. The graying of a central circle is something I've never seen in a Tele Vue eyepiece although I have seen it in a few other wide angle eyepieces before. This was seen in the AP Traveler and less noticeably in the NP-127 so it's not being caused by a central obstruction of the objective.
For those who have seen a graying of the central FOV caused by the secondary of a DOB, this is kind of similar but not nearly as pronounced or anywhere near as dark. At night it's difficult to see. During the daylight it appeared most noticeably when looking at something backlit and silhouetted against the sky. I confirmed this effect in the Traveler and the NP-127 straight through (no diagonal) as well as using both a 2" AP Maxbright and TV Everbright. The effect is very slight and I doubt most people would even notice unless they’re looking for it.
Finding and holding the 'exact' eye position seems to be harder for me with the Ethos than the Nagler eyepieces. I'm not entirely sure why but I think it's partly because you get a partial view well off the correct position in all directions. Also, the eye relief is long enough that it's a bit harder to hold an exacting eye point unless you use the eyecup. If the Ethos had an adjustable eyecup like some of the other TV eyepieces, I think it would be easier to deal with this issue. Minor issue but take note if you have trouble holding your head perfectly still, hovering over an eyepiece. If possible, use the eyecup, sit down, and take a stable position especially if you're going to be viewing for a long period. [note: I've slowly gotten used to the Ethos and hardly notice any eye positioning difficulty now.]
The eye relief of the Ethos is only slightly better than the 13mmT6 and not quite as good as the 12mmT4 which means it’s tight for eyeglass wearers but should be usable. Without a paracorr, the Ethos does exhibit a small amount of aberration in DOBs. IMO you shouldn't complain about the price of a Paracorr if you're looking at a $600+ eyepiece. (It'll probably help your other WA eyepieces too.) IMHO the issue of Field Curvature with most scopes is somewhat moot as the FOV is so wide and the FC is so far to the edge, it’s not noticeable unless you move your eye and look for it. Besides, a slight tweak of the focus usually finds a mid point of focus that allows my eye to adjust to bring the entire FOV in focus. When used in a Newtonian scope, a Paracorr noticeably tightens up the edges so it displayed the type of pinpoint stars across the entire FOV that is usually associated with APOs, even right at the edge. IMO the 13mmT6 is smaller, lighter, and possibly a hair brighter and tighter than the 12mmT4 due in part to the FL difference, but it's difficult to see any optical quality difference between the 13mmT6 and the Ethos. The 12mmT4 has very nice eye relief, has the Instadjust eyecup (hate it or love it) and provides a sense of immersion. For me the Ethos provides an even greater feeling of being absorbed in the stars than the 12mmT4.
When viewing the perception of the edge of the FOV simply dissolves away with the Ethos. When comparing the Ethos to the Naglers in daylight I noticed that I could not actually see the entire edge of the FOV clearly with the Ethos. I've been blessed with a wide field of vision and am aware of the entire edge of the FOV when daylight viewing with Naglers if I think about it. With the Ethos I have to actively move my eye to clearly bring in the edge. That means I can't see the entire circle of the edge of the FOV clearly with the Ethos. I know several people who express the same feeling with Naglers. The only other eye piece I've encountered that provides me with this feeling of an expansive FOV is the 30mm, 88°FOV Lietz. For those of you old enough to remember the Nikkor 8mm, 180° Fisheye camera lens, the experience of using the Ethos for the first time was somewhat akin to first using the Nikkor Fisheye lens but without the distortion!
As to actual viewing, I'm still somewhat in awe when using the Ethos in a good scope. Looking at M42 with the 12.5" StarMaster I don't think I've seen such whiffs of tangled nebulosity extending to the limit of the field in this scope. It’s amazing to see a clear and crisp Trapezium with pinpoint E & F stars resolved, amongst this beautiful field.
The Swan Nebula (M17) showed extensive texture in the nebulosity. The entire swan shape is easily seen through a 4" scope. While the 13mm T1 & T6 Naglers both worked well viewing M17, the expansiveness of the Ethos just brings in so many stars it gives me a sense of being plunged into the nebulosity.
Swinging over to M31 I wasn’t expecting the Ethos to work well since this is where the Leitz 30mm and 26 Nagler excel. To my pleasant surprise M31/M32 and M110 were wonderful through the Ethos. Because of the increased magnification, there was more detail and the sky was blacker while still very encompassing.
Panning around I swept across M8. It was surprising to find that M8 and M20 just fit into the FOV. Normally you only see these two in the same FOV with something around a 20mm Nagler. Because of the higher magnification with the Ethos, the view of this pair together was extraordinary. The Ethos is a great eyepiece for scanning the Milky Way. Usually I use the 30mm Leitz for panning the Milky Way and the 13mm Naglers work nicely too, but scores of additional stars seemed to jumped out against the dark black background of the Ethos. It's a delight to use for just wandering around the Milky Way. There's more of a feel of being engulfed in the stars that I don't get from the 12mm, 13mm, or even 16mm Naglers.
Normally I don't use Barlows, PowerMates, or Barcon for visual viewing. The Ethos did a surprisingly good job with all 3. the Ethos surprised me by working well even with a 4x PowerMate as compared to a 3.5mm Nagler & Pentax XW. The added FOV with the Ethos and 4x is significant as compared to the 3.5mm eyepieces. It's not a huge problem but the Ethos and a PowerMate aren't even close to par focal with these two 3.5mm eye pieces. It takes considerable focus adjustment to switch between them.
The Ethos really does add a new dimension to viewing and it's not just the extra wide field of view. The center to edge sharpness is outstanding with a good scope (and Paracorr for DOBs). My suspicion is the Ethos will develop into a popular a line like the Naglers in the next decade assuming TeleVue chooses to expand the line. IMHO there is one caveat, if you view from a heavily light polluted site, you can live without the Ethos. From sites in and near Denver & Tucson, I felt the Ethos 100° FOV just pulls in too much of the light pollution for good viewing even with filters.
The Ethos provides the delightful effect of combined central & peripheral vision encompassing a huge FOV so broad you can't clearly perceive the entire edge of the FOV at once. When using this eyepiece forget about focusing on the stars at the edge. Use the eyepiece for what it's mean for; look at the center of the FOV and let the edges melt away. If I had to choose only one eyepiece to keep, the Ethos would be in the front runners of my choice.Sort by
|Apparent Field of View
|1.25" (31.7mm) and 2" (50.8mm)
|Bolt Case Included
|Yes - Free Agena Eyepiece Container
|Bolt Case Size
|Eye Relief by Design
|Field Stop Diameter
|Standard 1.25" Filter Thread (M28.5 x 0.6)
|Rubber Eye Guard
|Blackened Lens Edges
- Suitable for use with Tele Vue Bino Vue binoviewer
|Eyepiece Focal Length
|10.1mm - 15mm
|Eyepiece Field of View
|Over 80 degrees
|Tele Vue Ethos
|With safety undercut