The 10mm TeleVue Ethos is a "do-it-all" eyepiece that is perfect for all telescopes that can utilize this focal length. And, as it fills the hole between the 13mm and 8mm Ethos eyepieces, the 10mm makes an ideal centerpiece for a state-of-the-optical-art 17mm/10mm/6mm Ethos set.
The 10mm Ethos has a soft rolldown eyecup. It shields your eye from ambient light (from a neighbor's security light, for example) to improve the image contrast. With a usable eye relief of 15mm, the 10mm Ethos normally might 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 10mm Ethos has all the high contrast, comfortable eye relief, and full field on-axis sharpness virtues that astronomers have come to expect from a TeleVue eyepiece. It has well-controlled astigmatism, low field curvature, and virtually no lateral color or angular magnification distortion. It addition, it has low pupil sensitivity (kidney bean effect) for daytime use. While its 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 10mm 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 10mm Ethos gives you dramatic views that are simply not possible with a narrower field similar focal length eyepiece, no matter what telescope you use. In addition, the smaller exit pupil inherent in the 10mm focal length reduces eyesight limitations due to astigmatism when compared with the larger exit pupils of longer focal length eyepieces.
The 10mm 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 10mm Ethos has a maximum barrel diameter of 61mm, making it more usable in binoviewers than its larger diameter 13mm big brother. In a binoviewer, a pair of 10mm Ethos eyepieces provides the ultimate in virtual 3-D "spacewalk" observing.
The 10mm 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.
