13mm 1.25"/2" 100° field Ethos

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A review in Sky & Telescope magazine gave the 13mm Ethos five stars, meaning “Sensibly perfect. No meaningful improvements possible.” The reviewer commented, “As revolutionary today as the original 13-mm Nagler eyepiece was when it was introduced in 1981, the 13-mm Ethos sets a new standard for wide-field observing. The on-axis performance is second to none, while the 100° apparent field is unprecedented for an astronomical eyepiece . . . if I were dropped on a desert island tomorrow with the 12-inch scope and only one eyepiece, I’d want it to be the Ethos.”

With a 13mm focal length that evokes that of the original and revolutionary 13mm Nagler eyepiece, the field of this new 100° apparent field Ethos eyepiece is nearly 50% larger in area than the 82° field of a “space-walking” 13mm Nagler. The TeleVue Ethos delivers the true field size of a longer focal length (but narrower apparent field) eyepiece, 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 13mm 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 13mm 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 has concentric 1.25” and 2” barrels that allow it to be used in both 1.25” and 2” focusers and star diagonals without the need to change the diagonal or eyepiece adapter. 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 barrel diameter of the current version of the 13mm Ethos has been reduced slightly to 62mm, from the 63.5mm of the first versions to be shipped. This will allow the use of two 13mm Ethos eyepieces in a binoviewer, providing a minimum interpupillary distance of 62mm. This spacing will be usable for the majority of observers, but some people with narrower than average eye spacing may not be able to use this combination. If you are a very serious binoviewer astronomer, a pair of 13mm Ethos may be worth a try.

A commentary on a Cloudy Nights forum, quoted by TeleVue, said, “Forget about the 100-degree field (well . . . I know you can’t but . . .), this is quite simply the finest eyepiece I’ve ever seen – period! Contrast, sharpness, light-throughput, etc. are all just amazing. There is simply NO ghosting or other internal reflections . . . the background is jet-black and the stars (even in my 28” f/3.66) are absolute diamond-points to the very edge!(P> “I've owned and used all of the “gold standards” over the years and NOTHING I’ve seen can match this!

“Along with about a half-dozen other observers we did “A/B” testing with other top-of-the-line 13 and 14mm eyepieces (M-51, Thor’s Helmet and M-42 were the targets). EVERYONE agreed that the ETHOS seemed to add additional inches of aperture. The increased detail in all of the objects was instantly apparent!

”As a bonus, the fine detail on Saturn equaled or exceeded the best “planetary” eyepieces any of us had ever used. And, again, NO ghosting or internal reflections. This baby does it all.

“And, as for the 100 degree field, Vic said it best . . . ‘you feel like you're going to fall in’ . . . ‘the scope just gets out of the way and it’s like you're standing in space looking at the objects.’”

The 13mm TeleVue Ethos eyepiece will accept TeleVue Dioptrx eyesight astigmatism correcting lenses.

Field of view:
The field of view (FOV) is the amount of observable world one can see at any given moment.
Eye Relief:
Eye relief is the distance from the last surface of the eye lens of an eyepiece to the plane behind the eyepiece where all the light rays of the exit pupil come to a focus and the circular image is formed, sometimes called the “Ramsden Disk.” This is where your eye should be positioned to see the full field of view of the eyepiece. If you must wear glasses because of astigmatism, you’ll usually need at least 15mm of eye relief or longer if you want to see the full field of view with your glasses on.

A note on our eye relief figures: Quite often, our eye relief figures will differ from those of the manufacturer. This is because we measure the “usable” eye relief, while the manufacturers specify their usually-longer (but technically correct) “designed” eye relief.

The eye lens of the eyepiece is normally recessed below the rubber eyeguard or rubber rim of the eyepiece to keep the lens from being scratched during use. An eyepiece might have a “designed” eye relief of 15mm (and the eye relief will truly measure 15mm from the eye lens to where the image forms). However, if the eye lens is recessed 3mm below the eye guard, the Ramsden Disk forms only 12mm above the eyepiece body (the 15mm “designed” eye relief, less the 3mm of eye relief made unusable by having the eye lens recessed into the body of the eyepiece). This “usable” eye relief of 12mm (measured from the rolled-down eyeguard – the closest point you can get your eye to the eye lens – to where the image forms) is the eye relief figure we would measure and list in this website.

Why is it important to list the “usable” eye relief? For those people who don’t wear eyeglasses while observing, a few mm difference between the eye relief they expect from the manufacturer’s literature and the shorter eye relief they actually get in real life doesn’t mean a lot. They can simply move a little closer to the eyepiece to see the full field, and never realize that the eye relief is a little shorter than they expected. However, some people must wear eyeglasses while observing, because of severe astigmatism. These observers can’t move closer to the eyepiece if the eye relief is shorter than expected because their glasses get in the way. For these people, the real life “usable” eye relief is more important than the technically correct but sometimes not fully usable “designed” eye relief. We measure and list the actual usable eye relief so that people in the real world can pick the eyepieces that will work best for them.

Focal Length:
This is the length of the effective optical path of a telescopeor eyepiece (the distance from the main mirror or lens where the lightis gathered to the point where the prime focus image is formed). Focallength is typically expressed in millimeters.

The longer the focallength, the higher the magnification and the narrower the field of viewwith any given eyepiece. The shorter the focal length, the lower themagnification and the wider the field of view with the same eyepiece.

Barrel Size:
The industry standard diameter, as of 2011, is 1.25" and is the most common.  Other sizes available are .965" and 2".
The weight of this product.
20 oz.
Limited Lifetime
There are currently no Cloudy Nights reviews associated with this product

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Overall Product Rating: AstronomicsAstronomicsAstronomicsAstronomicsAstronomics(5.00)   # of Ratings: 4   (Only registered customers can rate)

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1. Craig on 5/1/2013, said: AstronomicsAstronomicsAstronomicsAstronomicsAstronomics
The 13mm Ethos is an absolutely spectacular eyepiece. I use mine primarily in a 18" Obsession Classic f4.5 and rarely switch it out. Combined with a Paracor, images are sharp edge to edge, even on the planets, which is a real luxury on a dob without tracking. The views are pure and expansive. Planetary images are crisp and clear, with subtle shading and tremendous detail on both Jupiter and Saturn. Globular clusters are wonderful. Star colors are obvious. Nebula and galaxy contrast is fabulous. The moon is a whole new experience. It's super easy to use, with none of the kidney-bean blackout or sensitivity to eye position that I've had trouble with on some earlier designs. I use it for outreach as my standard eyepiece and everyone seems to be able to use it easily, even first time viewers, which I think says a lot.

I really can't say enough about this eyepiece. Although it's pricy, for me it's worth every penny and it became my favorite the moment I tried it in my scope. I also have the 6mm and 8mm versions, which are great, but the 13mm is the real standout for my scope and viewing style.
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2. Vic on 4/30/2013, said: AstronomicsAstronomicsAstronomicsAstronomicsAstronomics
I thought long and hard before spending $650 on an eyepiece, having taken up this hobby 7 months ago. It cost twice what my used Dobsonian telescope did. However, the consensus on the Cloudy Nights forums and others is that the Ethos 13mm is probably one of the finest eyepieces made, hitting the sweet spot as a mid focal length with a wide field of view.

The field is flat and true right to the edge of the incredible 100 degree AFOV. I initially bought it to use in my 1.25" adapter but have since decided that my future eyepieces will all support 2". The Ethos does both. Add to that a lifetime warranty and this becomes an investment that will be with me for decades.

I purchased this over the phone and it was shipped (free) the next day, insured and signed for. Astronomics was great.
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3. Chris on 4/2/2013, said: AstronomicsAstronomicsAstronomicsAstronomicsAstronomics
If I were asked to limit myself to 2 eyepieces, this would definitely be one of them (the Pentax XW 7mm being the other). As an eyeglass wearer, the 15mm eye relief it at the edge of what I like, but the wide angle views are absolutely stunning. The contrast is very good, and you get near edge to edge sharpness. The eyepiece is extremely well made, and more than likely you're going to keep this eyepiece no matter what scope you use.
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4. Kevin on 3/13/2013, said: AstronomicsAstronomicsAstronomicsAstronomicsAstronomics
This is one of my favorite and most heavily used eyepieces (next to the 17mm Ethos). I use this in an 8 SE (with and without a focal reducer), and I really love the wide field of view. Everything you have read about the Ethos line where it is described as "like floating in space", I have found to be true. I have to move my head around to get the full field of view, but I don't mind that. The contrast and eye relief are great as well, but the really wide view is what I love the most.

The 13mm is a little heavy (around 1.3 pounds, according to Tele Vue) but the weight is not at all detrimental. I have it in a William Optics 2" diagonal on my 8 SE with the standard mount and the views are solid. The motor does not struggle a bit and the balance is fine. One other thing is that I have 2" filters, so when I ordered this eyepiece, I also ordered Tele Vue's 2" barrel extender (manufacturer part number EBX-2120) so that I can use my 2" filters with it.

The Ethos eyepieces are pretty expensive but they are worth it to me. I am buying eyepieces in order to (hopefully) keep them around for life, so I view it as a good investment for any telescope that I will get in the future as well. This eyepiece is a joy to use and I am very happy to own it.
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65mm x 120mm eyepiece container
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TeleVue - 13mm 1.25"/2" 100° field Ethos

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TeleVue - 13mm 1.25"/2" 100° field Ethos
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Clear skies,

The 100° apparent field of this new TeleVue 13mm Ethos eyepiece provides a field area more than 50% larger than the “space-walking” 82° field of a 13mm Nagler . . .

. . . our 38th year