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Silver 2-inch telescope eyepiece barrel with rubber grip and lens caps

Tele Vue

Tele Vue 21mm Ethos 2 inch 100 degree eyepiece

SKU CH-42SP-MKRE8

Offers a 100° apparent field with 21mm focal length and 15mm eye relief for immersive astronomy

  • Expansive 100° apparent field immerses you in the night sky
  • 15mm eye relief reduces strain for comfortable extended sessions
  • Advanced lens coatings maximize light transmission for brighter images
  • 21mm focal length delivers versatile magnification across celestial objects
  • Precision aberration correction maintains sharpness and contrast to the field edge

Immersive 100° Astronomical Eyepiece

The Tele Vue 21mm Ethos 2 inch eyepiece delivers a 100 degree apparent field of view for immersive deep-sky observing. Its 21mm focal length provides versatile magnification suited to larger nebulae and rich star fields. Advanced optical coatings maximise light transmission and contrast across the entire field. The design pushes 2 inch barrel limits to achieve maximum true field without significant vignetting.

Suited For Visual Deep-Sky Observers

Astronomers who prioritise expansive, sharp views of extended objects will benefit from the generous 15mm eye relief and aberration-corrected optics. Observers requiring higher planetary magnification or using focusers limited to smaller barrel formats should consider alternative eyepieces. The wide field design is optimised for low-to-medium power scanning rather than high-power detail work.

21mm Focal Length Determines Magnification

The 21mm focal length sets the magnification and true field of view when paired with a specific telescope. Divide the telescope focal length by 21 to calculate the resulting power for your instrument. This single figure decides whether the eyepiece frames your intended targets correctly.

Highlights

  • Expansive 100° apparent field immerses you in the night sky
  • 15mm eye relief reduces strain for comfortable extended sessions
  • Advanced lens coatings maximize light transmission for brighter images
  • 21mm focal length delivers versatile magnification across celestial objects
  • Precision aberration correction maintains sharpness and contrast to the field edge

Specifications

No published specifications for this item yet.

Questions about this item

What barrel diameter does the 21 mm Ethos need to fit my focuser?

The eyepiece uses a standard two-inch barrel, so it fits any focuser or diagonal that accepts two-inch eyepieces.

How do I install the 21 mm Ethos, and what step do people often miss?

Slide the eyepiece into the two-inch drawtube or diagonal and tighten the locking screw; the step many forget is engaging the safety groove so the eyepiece cannot fall out if the screw loosens.

What maintenance will the 21 mm Ethos need over time?

Clean the exposed lens surfaces only when necessary using a soft brush, air blower and optical cleaning fluid with a lint-free cloth; the internal optics are sealed and require no user service.

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