Tele Vue 21mm 2" 100° field Ethos


Availability: In stock

The 100° apparent field of this new TeleVue 21mm Ethos eyepiece provides a field area 64% larger than the "space-walking" 82° field of a 20mm Nagler, and 36% larger than a 22mm Nagler . . .
Our Product #: TE21
TeleVue Product #: ETH-21.0
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Product Description

With a 21mm focal length, the field of this 100° apparent field Ethos eyepiece is nearly 64% larger in area than the 82° field of a "space-walking" 20mm Nagler. The TeleVue Ethos delivers the true field size of a longer focal length (but narrower apparent field) eyepiece, such as a 26mm Nagler, but has the benefits of the higher power and darker sky background that are inherent in a shorter focal length.

There is a soft rolldown eyecup to shield the eye from ambient light (from a neighbor's security light, for example) and improve the image contrast. At a usable eye relief of 15mm, the 21mm Ethos would normally somewhat vignette the field of view for eyeglass wearers. However, since the 100° field is so wide that you can't see the full field without having to move your head from side to side to take it all in anyway, vignetting in the conventional sense is not a problem.

The 21mm Ethos has all the virtues that professional and amateur astronomers have come to expect from a TeleVue eyepiece: high contrast, comfortable eye relief, and full field sharpness - with well-controlled astigmatism, field curvature, lateral color, angular magnification distortion correction, and low pupil sensitivity (kidney bean effect) for daytime use. While sharpness is inherent to the optical design itself, the contrast is maximized through the intelligent use of flat finished baffles and ultra low reflectance, high efficiency coatings that are tuned to the glass composition of each lens element.

The Ethos is designed for 2" focusers and star diagonals only. A safety groove is machined into the 2" chrome barrel to engage your focuser thumbscrew. This will help prevent the eyepiece from falling should the thumbscrew accidentally loosen while observing.

The 21mm TeleVue Ethos eyepiece will accept TeleVue Dioptrx eyesight astigmatism correcting lenses.

Please note the 36 ounce (2.25 lb.) weight of this eyepiece if you have a Dobsonian telescope. Its use may require some temporary rebalancing of your scope, or the use of a TeleVue #TVEQC equalizing adapter with lighter 1.25" eyepieces to avoid balance problems.

Tech Details

Barrel Size 2"
Eye Relief 15mm
Field of view 100
Focal Length 21mm
Weight 2.25 lbs.
Warranty Limited Lifetime


Review by:
Great eyepiece! The views are what you expect from Televue, wide and well corrected. This focal length is awesome, because it will work in a long focal length SCT or a fast dob or refractor. It has become one of my 3 most used eyepieces in each of my scopes... (Posted on 10/31/2019)
Review by:
The best way I can describe the stunning views from this eyepiece is to imagine you are peering out into space from a bubble-shaped window on a spacecraft. You must move your eye around to take in the totality of the view. Beware, this is a substantial assembly. You must account for its mass on your telescope. The quality of workmanship is excellent. (Posted on 10/4/2019)
Review by:
Such an amazing view! This eyepiece never ceases to amaze me. The total immersion of the 100 degree apparent field of view is breathtaking. It's as if you could reach out & touch whatever you are viewing. If you have never tried it find someone who has one and give it a look. You may be spoiled for all others! I'm never sorry for buying these eyepieces-always a pleasure to use. (Posted on 7/24/2019)
Review by:
I have many eyepieces. However, the 21mm Ethos is hands down my favorite eyepiece that I own. It looks absolutely stunning through my Celestron 8" SCT. It is the the most versatile eyepiece in my collection. I cannot believe how amazing both wide field targets like the double cluster and small targets like double stars appear in this eyepiece. The contrast through the eyepiece is fantastic. This will make you sold out on TeleVue. If I could only own one eyepiece, this would be it. Don't think, just buy it. P.S. I am not an owner or affiliated in any way with TeleVue! (Posted on 8/4/2017)
Review by:
I don't have much experience with with high end eye pieces - so, when I decided to take the plunge I went all-in for TeleVue Ethos. I've read mixed reviews about the "thrill" of 100 degree apparent field of view being overrated... It's not... The view is amazing and the spacewalk view is everything you're going to want. It turns your telescope into something new and exitingly unexpected. And to top it off - as investment goes - I can always add DIOPTRX to compensate for my changing eye stigmatism. Traumatic brain injuries have left me with a sight condition that changes my vision from 20/20 to something much less and akin to a palsy or stignatism. Anywho - I couldn't be happier. (Posted on 8/4/2017)
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