TeleVue Ethos 17mm – 100° 2″ Eyepiece

TeleVue Ethos 17mm : 100° 2″ Eyepiece: Ethos eyepiece with 100-degree field of view

The Ethos 17 mm opens the series of 17, 10, and 6 mm and is the lowest magnification model that can still handle moderate light pollution. With a field stop of 29.6 mm, the true field of view is close to that of a 26 mm Nagler, but at a higher magnification.

This is a 2-inch eyepiece. A focuser or star diagonal with a 2-inch connection is therefore required.

What a 100-degree field of view does

A classic Ploessl has 50 degrees, a Nagler has 82 degrees. At 100 degrees, your eye can no longer take in the field at once: you’re looking around the image instead of *at* it. That’s the effect the Ethos series is known for.

Practically, this also means that objects remain in view for longer. On a manually tracked Dobson, this saves constant readjustment.

Overview with a dark background

At low magnification, the sky background becomes lighter, especially under an urban sky. Because the Ethos achieves the same true field of view at a higher magnification, the background remains darker and faint nebular structure stands out better.

For extended objects like the North America Nebula or the Pleiades, this is the model that combines overview and contrast.

Viewing Comfort and Dioptrx

The eye relief is 15 mm at every focal length in the series. The height of the foldable eyecup is adjustable, so your eye is always in the same position.

If you wear glasses due to astigmatism, you can replace them with Dioptrx on the eyepiece. This corrects your own cylindrical aberration without the eyeglass lenses costing contrast and eye distance.

In your telescope

In a telescope with a brand point spread function of 1,200 mm, this eyepiece provides approximately 71x magnification with a true field of view of about 1.41 degrees. You can calculate this for your own telescope using the field stop: true field of view = 57.3 × field stop divided by the telescope’s brand focal length.

The field stop on this model is 29.6 mm. That number—and not just the brand point spacing—determines how much of the sky you actually see.

Included

• Foldable rubber eyecup
• Eyecup protector
• Dust cover for the stitch
• Filter thread abandoned

Featured accessories

Every Ethos eyepiece is compatible with the TeleVue Dioptrx, a corrector for astigmatism that allows you to observe without glasses. If you’re using a fast Newtonian, the Paracorr coma corrector will bring out that last bit of edge sharpness. For a 2-inch focuser, an Everbrite zenith mirror is the logical addition, and an eyepiece case protects your investment while on the go.

For whom yes and for whom no

• ✓ Large nebulae and open star clusters
• ✓ Observing under a sky that is not completely dark
• ✓ Telescopes with a 2-inch focuser
• ✗ Focusers with only a 1.25-inch connection
• ✗ Anyone who needs a lightweight eyepiece

Specifications

All wide-angle eyepieces are on the page featuring wide-field eyepieces. You can find the complete selection of this brand on the TeleVue brand page.