Product Description
The TeleVue 8mm Ethos eyepiece raises the bar for shorter focal length eyepieces. It expands the apparent field of view to an astonishing 100°, while matching all the key performance criteria of its highly-acclaimed 13mm big brother.
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. With a usable eye relief of 15mm, the 8mm Ethos might normally somewhat vignette the field of view for some 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 8mm Ethos has all the virtues that 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 composition of each lens element.
Compared to any longer focal length eyepiece (even the 13mm Ethos), the higher magnification of the 8mm Ethos provides a darker sky background, with fainter stars becoming visible and more detail showing in all deep sky objects. With its incredible 100° field, the 8mm Ethos gives you dramatic views that are simply not possible with a similar focal length eyepiece, no matter what telescope you use. In addition, the smaller exit pupil of the 8mm reduces eyesight limitations due to astigmatism when compared with longer focal length eyepieces.
The 8mm 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. A rubber grip ring provides a sure grip in cold weather when wearing gloves or mittens.
The 8mm Ethos has a maximum barrel diameter of 53.4mm, making it usable in many binoviewers for the majority of (but not all) observers. In a binoviewer, a pair of 8mm Ethos eyepieces provides the ultimate in virtual 3-D "spacewalk" observing.
The 8mm TeleVue Ethos eyepiece will accept TeleVue Dioptrx eyesight astigmatism correcting lenses. It is parfocal with TeleVue Radian, Plössl, Type 6 Nagler, and 1.25" Panoptic eyepieces.
Tech Details
| Barrel Size | 1.25"/2"" |
|---|---|
| Eye Relief | 15mm |
| Field of view | 100 |
| Focal Length | 8mm |
| Weight | 15.2 oz. |
| Warranty | Limited Lifetime |
Reviews
The 100 degree AFOV is wide enough that you have to actively look for it, meaning the boundaries of the view kind of melt away, leaving you with a true floating in space feeling. M13 shows nice pinpoint stars in the center of the field on a steady night. Unable to evaluate edge performance due to lack of a coma corrector, but stars do not have the telltale "sea gull" shape of coma + astigmatism, and look purely comatic, which tells me the edge of the field is well corrected.
On nights that support it, this eyepiece delivers tack sharp views of the planets.
When comparing this eyepiece against the 8mm TV Plossl, I did notice the Plossl has less scatter and slightly snappier focus, but that's to be expected given the lower element count.
My biggest complaint about the 8 Ethos is the eye relief feels a bit tight, at least compared to the 21 Ethos, maybe by a difference of about 1mm or so effective eye relief. It feels like a little more work to look through it compared to the 21E.
After using long eye relief ultrawides like the ES 92 series the Docter, the tighter relief of the 8E makes it slightly less comfortable to use than I'd like, but it's still usable given the wide AFOV. (Posted on 9/9/2019)
The 8mm Ethos is a great high power outreach eyepiece to show the entire moon or white light filter solar disc with lots of detail, or give a nice first view of Jupiter or Saturn, combined with minimal alt-az mount tracking distraction thanks to the 1 and 2/3 degrees field of view. Since getting this 8mm I use it as the high power eyepiece for this scope (a few other eyepieces range down to a binocular-like 12x and 5.6 degree field of view). The 8mm Ethos offers a nice combination of sufficient magnification and the time for relaxed viewing to see fine, high contrast detail to the limit of my vision, between infrequent tracking nudges thanks to the wide, sharp field of view.
It also resolves into pinpoint stars whatever clusters a 3-inch scope can reach, including the edges of brighter globulars, without being too dim an exit pupil. It has a good true field of view for most deep sky objects, but the 8mm is usually a 2nd look eyepiece after a lower power, wider true field eyepiece is used for dark sky site deep sky viewing. (Posted on 11/10/2018)
8" UTI f4.5 UNGUIDED dob scope.
Is it worth the money? Foe me YES. Why? YES it is expensive, but I decided some time ago to do it right the first time and avoid the wasteful habits of my youth; buy what is "adequate" and learn later I want to take the next step....only to spend MORE MONEY than if I'd saved longer, did my homework, and made the Ethos choice first.
Specifics:
I don't wear glasses so eye relief is quite comfortable. I've read different feelings from glasses wearers, but they generally gravitate toward good to go...
My scope is unguided, so the 100 degrees (vs 72/82/etc) affords me longer viewing times between scope adjustments. Very nice, neutral, flat field too!
Just a general comment on the 100 deg AFOV with the Ethos: the ability to pair high magnifications with the ability to more fully frame a large(r) subject at the same time is a KEY factor to realizing what the Ethos has to offer over the competition.
Also, the 8mm is not too heavy so it has minimal impact on balance and the need to adjust things. It's a winner.
Buy fewer, high quality EP's and you will be happier in the long run. (Posted on 8/4/2017)
Astronomics was great; free shipping and delivered three days later. (Posted on 8/4/2017)
