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TeleVue Ethos 10mm 100° Eyepiece - 2" / 1.25"
The Tele Vue Ethos 10mm sits at the strategic "power center" of the Ethos line. While the 21mm and 13mm models are celebrated for their wide field framing, the 10mm focal length is where the 100° Apparent Field of View (AFOV) truly begins to pull back the curtain on the deep universe. It offers a higher magnification level that darkens sky backgrounds significantly, making it an essential tool for resolving the core details of distant galaxies and globular clusters.
The 100° apparent field removes the visible field stop in most observing conditions, creating the classic ‘spacewalk experience’ where the eyepiece frame disappears. At this focal length, the magnification is high enough to reveal intricate structural details in planetary nebulae, yet the field of view remains wide enough to keep those objects centered in non tracking telescopes for remarkably long periods. Best of all, it is parfocal with the Ethos 13mm, allowing for seamless transitions during your observing session.
High Magnification Without the "Tunnel Vision"
In traditional high power eyepieces, increasing magnification usually means a claustrophobic decrease in the field of view. The Ethos 10mm shatters this limitation. By providing a 100° field, it allows you to observe at high power while still seeing the object’s celestial neighborhood.
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Deep Sky Resolution: Perfect for resolving M13 or M92 into thousands of pinpoint stars while maintaining a wide, dark background.
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Lunar Exploration: Provides an incredibly immersive view of the lunar surface, allowing you to fly over craters and rilles with zero sense of equipment interference.
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Exit Pupil Efficiency: In most f/5 to f/10 telescopes, the 10mm focal length produces an exit pupil that balances brightness and contrast perfectly for the human eye.
The Universal Hybrid Design
The 10mm Ethos is designed for maximum compatibility across your entire telescope collection. Its hybrid barrel system allows it to slide into 1.25" focusers for portable refractors or 2" diagonals for larger instruments.
Every internal optical surface is multi coated and every lens edge is blackened. This meticulous attention to detail results in world class contrast. When observing near a bright object like the Moon or Jupiter, the 10mm Ethos suppresses ghosting and internal reflections, ensuring the views remain "inky black" and pure.
Ergonomics and Dioptrx Compatibility
Weighing in at approximately 1.1 lbs (500g), the 10mm Ethos is a manageable addition to any imaging train. Like all eyepieces in the Ethos series, it features a consistent 15mm of eye relief, providing a comfortable and predictable viewing experience for all observers.
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Dioptrx Ready: For those with astigmatism, the 10mm Ethos is fully compatible with the Tele Vue Dioptrx corrector, allowing for sharp views without the need for eyeglasses.
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Safety First: Features the signature Tele Vue safety undercut, preventing the eyepiece from falling out if the focuser screws loosen.
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Is the 10mm Ethos better than the 13mm for deep sky?
The 10mm offers specific advantages for high contrast targets and smaller objects:
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Darker Sky: The 10mm provides a smaller exit pupil, darkening the background sky glow more than the 13mm, which makes faint nebulae and galaxies "pop."
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Higher Resolution: It is generally superior for resolving the cores of globular clusters (like M13) and detecting planetary details.
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Parfocal Design: The 10mm is parfocal with the 13mm Ethos, allowing you to swap between these two "workhorse" focal lengths without refocusing.
How much eye relief does the 10mm Ethos have?
The 10mm Ethos features 15mm of eye relief, which is the standard across the entire Ethos focal length range:
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Consistency: Because all Ethos eyepieces (from 3.7mm to 21mm) share this 15mm eye relief, your head position remains identical when swapping focal lengths.
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Eyeglass Users: While 15mm is comfortable for most, those with severe astigmatism can use the Tele Vue Dioptrx system instead of glasses to maintain the full 100° view.
Why is the 10mm Ethos considered a perfect match for SCTs?
For owners of Schmidt Cassegrain Telescopes (8", 9.25", 11", and 14"), the 10mm Ethos is often the most used eyepiece in the kit:
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The "Sweet Spot" Power: In an 8" f/10 SCT, it provides 200x magnification with a 1mm exit pupil, which is widely considered the optimal balance of power and brightness for most atmospheric conditions.
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Framing: The 100° field provides enough context to frame most lunar features and mid sized deep sky objects that would feel "cramped" in narrower high power eyepieces.
Is the 10mm Ethos good for planetary viewing?
The 10mm Ethos is an exceptional planetary tool, provided your telescope has sufficient focal length:
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Long Focal Length Scopes: It is a great match for scopes like an 8" SCT or large Dobsonians with 1500mm+ of focal length where high magnification is easily achieved.
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Manual Tracking: The massive 100° field allows a planet to drift across the view for a much longer time before you need to nudge the scope, which is a major advantage for manual Dobsonian users.
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Contrast: With every lens edge blackened and advanced multi coatings, it provides the "cool" color rendition and high contrast necessary for lunar and planetary details.
Can I use the 10mm Ethos in a 1.25" diagonal?
Yes, the 10mm Ethos features a hybrid 2" / 1.25" barrel design:
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Weight Consideration: It weighs 1.1 lbs (500g). Ensure your 1.25" focuser or diagonal has a strong locking mechanism to support the weight.
Do I need a Paracorr with the 10mm Ethos?
This depends entirely on your telescope's focal ratio:
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f/4.5 or Faster: In fast Newtonians, the 100° field is wide enough to show the natural coma of your mirror. We highly recommend the Tele Vue Paracorr Type 2 for pinpoint stars to the very edge.
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SCTs and Refractors: Most Schmidt Cassegrain and refractor users find the field correction excellent without any additional correction.
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| Model # |
ETH-10.0 |
| Focal Length |
10 mm |
| Barrel Size |
2" / 1.25" Hybrid |
| Filter Compatibility |
Threaded for 1.25" filters |
| Apparent Field of View |
100° |
| Eye Relief |
15 mm |
| Field Stop Diameter |
17.7 mm |
| Weight |
17.7 oz (1.1 lb / 500 g) |
| Dimensions |
2.5" x 5.2" (63.5 x 132 mm) |
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