TeleVue Ethos 13mm 100° Eyepiece - 1.25"/2"

The Original 100° Masterpiece

The 13mm Ethos was the first eyepiece to successfully implement a well-corrected 100° field, and it remains a benchmark for the industry. This focal length provides a powerful magnification boost over lower-power finders, yet its field of view is wide enough to compete with most mid-range wide-angle eyepieces.

For most telescopes, the 13mm serves as the "primary" deep-sky eyepiece. It provides the ideal exit pupil for detecting subtle low-contrast features in spiral arms of galaxies or the delicate filaments of supernova remnants like the Veil Nebula. The 100° field isn't just about size; it's about context—allowing you to see a galaxy in relation to its surrounding star fields.

Superior Optical Engineering

Like all eyepieces in the Ethos line, the 13mm was designed by Paul Dellechiaie to meet the exacting standards of Al Nagler. It is engineered to be as sharp at the very edge of the field as it is in the center.

• Edge Sharpness: Stars remain tight, pinpoint dots across the entire 100° expanse, even in fast f/4 Newtonian reflectors.
• High-Contrast Coatings: Advanced multi-coatings and blackened lens edges ensure that stray light is eliminated, providing the inky-black backgrounds Tele Vue is famous for.
• Hybrid Barrel Versatility: The 13mm Ethos features a unique hybrid barrel design, allowing it to be used in both 2" and 1.25" focusers or diagonals, making it compatible with almost any telescope in your collection.
• Flat Field: The optical design minimizes field curvature, ensuring that you don't have to refocus as you move your eye from the center to the edge of the view.

Versatility and Application

The 13mm Ethos is a versatile performer. In long focal length telescopes like SCTs or large refractors, it provides high-power views of planetary nebulae and lunar details. In fast Dobsonians, it is the perfect "galaxy hunter," offering a dark sky background and enough power to resolve individual stars in globular clusters.

Because it creates such a massive true field for its magnification, it often allows you to keep an object in view for much longer in non-tracking telescopes compared to 50° or 70° eyepieces, making it a favorite for manual Dobsonian users.

Ergonomics and Dioptrx Compatibility

Despite its complex optical train, the 13mm Ethos is designed for comfort. Weighing just over 1 lb, it is significantly lighter than the 21mm version, making it easier to manage on smaller mounts.

• Eye Relief: The 15mm eye relief is well-balanced. While it provides an immersive view for most, it also accepts the Tele Vue Dioptrx system to correct for astigmatism, ensuring every user can see pinpoint stars without needing to wear glasses.
• Safety Features: The 1.25" and 2" barrel sections both feature safety undercuts to prevent the eyepiece from accidentally sliding out of the focuser.

Comparative Perspective: Why the 13mm?

In the Tele Vue hierarchy, the 13mm occupies a special place:

• vs. Nagler 12mm or 13mm: While the Nagler series offers a legendary 82° field, the 13mm Ethos provides nearly 50% more viewing area, significantly increasing the "immersion" factor.
• vs. Ethos 10mm or 17mm: The 13mm is often chosen as the "anchor" of an Ethos kit, sitting perfectly between the high-power 10mm and the wider 17mm or 21mm options.