Engineered to recapture the identical field of view astronauts enjoyed through the windows of their LEMs during the moon landings, Tele Vue's Ethos-SX 3.7mm Ultra Wide-Angle Eyepiece delivers an expansive 110° angle of view and offers a long eye relief, despite the short focal length, with high contrast and excellent on-axis sharpness; and virtually zero astigmatism or field curvature. Combining a hyper-wide apparent angle of view with its short focal length, this Ethos delivers high magnification with enhanced details when looking at the moon and planets, while still offering an immersive observational experience.

A unique design characteristic of the Ethos allows it to be used in the smaller, more common-sized 1.25" drawtubes and accessories; and a simple screw-on installation of the included adapter converts it for use in larger 2" versions. This provides users with an easy and convenient way to expand its functionality and versatility, without limiting its use or relying on eyepiece holder reducer adapters. This model is parfocal with a variety of Tele Vue eyepieces, requiring little or no refocusing when changing between them — greatly decreasing vibration and increasing convenience. A textured collar around the housing provides sure handling in cold weather or while wearing gloves, and a fold-down rubber eyecup allows for comfortable use with or without eyeglasses.

3.7mm Focal Length    Wide 110° Field of View    1.25 and 2" Diameter Barrel    Fully Multi-Coated Optics    Slip-Resistant Textured Surface    Parfocal with Select Eyepieces    Fold-Down Rubber Eyecup

Parfocality is only achieved when in the 1.25" mode

• Plössls
• Radians
• Type-6 Naglers
• Nagler Zooms
• 1.25" Panoptics

Parfocality is only achieved when in the 2" mode

• 10mm and 13mm Ethos

Related Questions and Answers

Q: 1. I'm looking for a longer eyecup and I'm wondering if this is a bit longer than the standard eyepiece? Because looking at reviews for every other other xt4 eyepiece online they seem like poorly made junk.

A: The Think Tank Photo EP-F Hydrophobia Eyepiece for Fuji X-H1, X-T3, X-T2, X-T1, GFX-50s is just a tiny bit longer than the standard eyepiece. This is designed to hold the Think Tank Photo Hydrophobia rain Cover in place.

Q: 2. Does this card read by the Sony XQD/SD card reader?

A: Yes. The following card will pick up in the sony reader.

Q: 3. Has anyone tried using this lens with any of the Leica or Voigtlander 35mm film cameras? The overview reads that it is optimized for use with digital cameras, but since it's working on the Sony A7 family (full frame) I'm not seeing why this wouldn't work on a 35mm camera. What am I missing?

A: Hello, I have used it and it works out perfect!

Q: 4. What is the difference between version III and Ii?

A: Both are leica cl mount. Version 2 is smaller. Version 3 is supposed to be free are color fringing artifacts when USC with digital cameras such as the A7. I am not sure, but for film, version 2 may be just fine.

Q: 5. Both reviews praise the sharpness of this lens but both gave only 4 stars. What are the negatives? Than you !

A: I'd be hard pressed to find negatives...maybe that it's not perfect and 5 is perfect. It has vignetting, it's manual focus, its weighty and has a small maximum aperture. I'm using it on a Sony a7ii and it's a treat. Gorgeous image, beautiful build, nice balance. The aperture ring is smooth and positive. Oh, the fixed hood is slightly awkward.

Q: 6. Will this fit the Fujifilm X-T4?

A: Yes, the Think Tank Photo EP-F Hydrophobia Eyepiece fits the Fujifilm X-T4 camera as well as the X-H1, X-T3, X-T2 and X-T1.

Q: 7. Whats the best adaptor to mount the sennhaiser MKE 440 to the Sony FDR-AX53?

A: Vello CB-510 Dual Shoe Bracket with Silicon Rubber Grip - B&H # VECB510

Q: 8. Can i use it on a Leica M3?

A: Yes, Match Technical 34mm E-Clypse MAG 1.25x Magnifying Eyecup for Leica Cameras BH #MAMAG125X34D is compatible with a Leica M3.

Q: 9. Is the ep-n compatible with a Nikon Z-7?

A: The Think Tank Photo EP-N Hydrophobia Eyepiece does not work with the Nikon Z7. For that camera you need this Think Tank Photo EP-NZ Hydrophobia Eyepiece for Nikon Z Series Camera. https://www.bhphotovideo.com/c/product/1495423-REG

Q: 10. Is the the correct eyepiece for a Canon 5Ds?

A: Yes