At a Glance
3.7mm
Focal Length
100°
Apparent FOV
15mm
Eye Relief
1.25"
Barrel Size
Score Breakdown
Overview
The Tele Vue Ethos 3.7mm is a specialized high-magnification eyepiece designed for observers who want to push their telescopes hard without sacrificing the immersive, wide-field experience Ethos eyepieces are known for. The 110-degree apparent field of view is genuinely remarkable at this focal length, giving you a view that feels more like floating in space than peering through a tube. In practical terms, this eyepiece shines on planetary detail, double stars, and tight globular clusters. Paired with a fast refractor or a long focal length reflector, the magnification it delivers will reveal features that shorter eyepieces simply cannot resolve.
The fully multi-coated optics hold up well in these demanding high-contrast situations, keeping light transmission strong even when conditions push back. One honest consideration: at 3.7mm, atmospheric seeing becomes your real limiting factor. On nights with average transparency or turbulence, this eyepiece will outpace what your sky can deliver. Reserve it for steady, clear nights and it rewards you generously.
The parfocal compatibility with a wide range of other Tele Vue eyepieces is a practical bonus, reducing refocusing time during a session. At $811.60, this is a serious investment suited to dedicated observers.
Key Features
- 110-degree apparent field of view provides an unusually immersive experience at very high magnification
- Delivers 62% more power than a 6mm Ethos while retaining a useful 68% of its true field of view
- Fully multi-coated optics support strong contrast and light transmission at demanding magnifications
- Parfocal with a broad range of 1.25-inch Tele Vue eyepieces, minimizing refocusing during observing sessions
- Includes a screw-on 2-inch adapter, also designed for parfocal compatibility with select larger Ethos eyepieces
- Best suited for planetary, double star, and globular cluster work on nights with steady atmospheric seeing
- Despite the extreme focal length, true field of view exceeds that of Tele Vue's 8mm Plossl, 6mm Radian, and 5mm Nagler Type 6
Specifications
| Focal Length | 3.7mm |
| Apparent FOV | 100° |
| Eye Relief | 15mm |
| Barrel Size | 1.25" |
| Design | Modified Nagler |
| Elements/Groups | 9/6 |
| Series | Ethos |
| Coating | Fully Multi-Coated |
| Waterproof | No |
Popular Telescopes for This Eyepiece
ZWO Seestar S50
68x / 0.7mm exit pupil / Apochromat Refractor
ZWO Seestar S30
41x / 0.7mm exit pupil / Apochromat Refractor
Unistellar eVscope Equinox
122x / 0.9mm exit pupil
Celestron NexStar 130SLT
176x / 0.7mm exit pupil / Newtonian
Amazon Reviews
Heavy but clearly better views than naglers. It depends on your mounts capabilities to use this eyepiece frequently or rarely. Because my mount's weight capacity I can use it rarely but still enjoying the views through it. Sharp and flying over effect !
One of the best short focal length mass produced eyepieces ever made (another one is TeleVue Ethos-SX 4.7 mm). Having 110 degrees of the apparent field is mind blowing. Great for observing planets. Totally worth money spent.
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