TeleVue Ethos 17mm 100° Eyepiece - 2"

The 100° Experience: Beyond Human Peripheral Vision

The primary draw of the Ethos 17mm is its breathtaking 100° apparent field of view. To appreciate the scale, consider that an 82° Nagler, once the gold standard for wide fields, offers significantly less viewing area. The Ethos 17mm provides a field that essentially matches or exceeds the limit of what the human eye can perceive at once, requiring you to move your eye to "look around" the scene.

In practical application, this massive field translates to efficiency. Because the 17mm focal length provides higher magnification than its 21mm sibling, it darkens the sky background significantly, yet the 100° field ensures you are still seeing a swath of sky typically reserved for low power eyepieces. You can frame the entire Double Cluster in Perseus or the expansive tendrils of the Veil Nebula while enjoying the resolution and contrast that come with a 17mm focal length. It effectively does the work of two eyepieces, functioning as both a wide field finder and a high contrast medium power powerhouse.

Precision Optics and Edge-to-Edge Correction

Tele Vue has built its reputation on the ability to handle "fast" telescopes. The Ethos 17mm is engineered to perform flawlessly even in f/4 or f/4.5 focal ratios, where lesser eyepieces often suffer from astigmatism or field curvature at the edges. This eyepiece maintains pinpoint star images across the entire 29.6mm field stop.

• Advanced Multi-Coatings: Every air-to-glass surface is treated with specialized multi-coatings to ensure maximum light transmission. This results in an exceptionally bright image, allowing you to catch the faintest hints of nebulosity in objects like the Horsehead Nebula.
• Superior Contrast: The internal mechanical design utilizes extensive baffling and blackened lens edges to eliminate stray light. When a bright star is just outside the field of view, the background remains inky black, free from the "ghosting" or glare that plagues many ultra-wide designs.
• Optical Geometry: The Ethos design specifically addresses angular magnification distortion. This means objects retain their correct proportions as they drift from the center to the edge, a critical feature for those using non-tracking Dobsonian telescopes.
• Neutral Color Balance: Tele Vue optics are celebrated for their "pure" white light transmission. There is no yellow or blue tinting, ensuring that the natural colors of star clusters and the subtle hues of planetary discs are preserved exactly as they are.

Optimizing the Exit Pupil for Deep Sky

For many observers, the 17mm focal length is the "Goldilocks" zone. In a standard f/10 Schmidt-Cassegrain, it yields a 1.7mm exit pupil, which is ideal for resolving globular clusters and planetary nebulae. In a fast f/4.5 Dobsonian, it produces a 3.8mm exit pupil, which is the perfect balance for deep sky work, providing enough light for the eye to perceive color and detail without the sky background becoming washed out by light pollution.

This versatility makes the Ethos 17mm the most used eyepiece in many collections. Whether you are hunting for small, faint galaxies or taking in the grandeur of the Pleiades, the 17mm provides the scale and brightness required for a truly transformative observing session.

Ergonomics and Mechanical Excellence

Despite its complex 100° optical design, the Ethos 17mm remains more manageable than the massive 21mm version. Weighing in at approximately 1.5 lbs (703 g), it is easier to balance on a wider variety of telescope mounts while still feeling like a robust, professional-grade instrument.

• Safety and Stability: The 2-inch barrel includes the signature Tele Vue tapered safety undercut. This design ensures that even if your focuser lock loosens slightly, the eyepiece remains securely held, preventing accidental drops.
• Viewing Comfort: The 15mm of eye relief is generous for an ultra-wide eyepiece. For those who observe with glasses, the Ethos 17mm is fully compatible with the Tele Vue Dioptrx system, which corrects for eyesight astigmatism so you can observe without the hindrance of spectacles.
• All-Weather Grip: The textured rubber housing provides a secure grip in humid conditions or when wearing gloves during winter observing sessions. The fold-down rubber eyeguard helps block lateral light pollution and positions the eye at the perfect distance for a comfortable view.

Comparative Perspective: The 17mm Ethos in the Kit

How does the 17mm Ethos compare to other legendary glass in the Tele Vue stable?

• vs. Ethos 21mm: The 21mm is the "finder" of the series with a wider true field. However, the 17mm is often preferred for smaller deep sky objects because the higher magnification makes them easier to see. The 17mm is also significantly lighter and easier to balance.
• vs. Nagler 17mm Type 4: The Nagler 17mm is a classic with a very comfortable 82° field. However, the Ethos 17mm provides a nearly 50% larger viewing area and improved edge correction, making it the definitive upgrade for those seeking the ultimate immersion.
• vs. Delos 17.3mm: If you require 20mm of eye relief for thick glasses, the Delos is a fantastic choice. But if you want the "floating in space" feeling that only a 100° field can provide, the Ethos is unrivaled.

Is the Tele Vue Ethos 17mm Right for You?

The Ethos 17mm is designed for the observer who refuses to compromise. It is for the astronomer who wants to see the spiral arms of M51 framed by the deep black of space, without the distraction of a narrow field stop. It is a "forever" eyepiece, designed to be passed down through generations. When you consider that it can replace several lower-quality eyepieces in your kit, the value becomes clear. You are paying for the highest level of craftsmanship available in the world of consumer optics today.