{"id":107546,"date":"2026-04-28T12:14:38","date_gmt":"2026-04-28T10:14:38","guid":{"rendered":"https:\/\/www.telescoop.nl\/?post_type=product&p=107546"},"modified":"2026-08-23T15:07:10","modified_gmt":"2026-08-23T13:07:10","slug":"televue-ethos-13mm-100-eyepiece","status":"publish","type":"product","link":"https:\/\/www.telescoop.nl\/en\/televue-ethos-13mm-100-oculair\/","title":{"rendered":"TeleVue Ethos 13mm 100\u00b0 \u2013 Eyepiece"},"content":{"rendered":"

TeleVue Ethos 13mm 100\u00b0: Eyepiece: Ethos eyepiece with 100-degree field of view<\/strong><\/h2>\n\n\n\n

The Ethos 13mm is the eyepiece with which the entire series began in 2007 and is still the best-selling model. The 22.3mm field stop provides approximately the same true field of view as a 26mm Ploessl, but at double the magnification.<\/p>\n\n\n\n

That's the core of the Ethos idea: a darker sky background and more detail, without sacrificing overview.<\/p>\n\n\n\n

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What a 100-degree field of view does<\/h4>\n\n\n\n

A classic Ploessl has 50 degrees, a Nagler has 82 degrees. At 100 degrees, your eye can no longer take in the field at once: you\u2019re looking around the image instead of *at* it. That\u2019s the effect the Ethos series is known for.<\/p>\n\n\n\n

Practically, this also means that objects remain in view for longer. On a manually tracked Dobson, this saves constant readjustment.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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Why this particular focal length<\/h4>\n\n\n\n

In the series 21, 13, and 8 mm, the 13 mm is the middle step. On most telescopes, it provides a magnification that remains usable under varying conditions, even when the seeing is not cooperating.<\/p>\n\n\n\n

At approximately 585 grams, this is a substantial eyepiece. On a Dobsonian with a light shroud, it's wise to check the balance before letting go of the instrument.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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Viewing Comfort and Dioptrx<\/h4>\n\n\n\n

The eye relief is 15 mm at every focal length in the series. The height of the foldable eyecup is adjustable, so your eye is always in the same position.<\/p>\n\n\n\n

If you wear glasses due to astigmatism, you can replace them with Dioptrx on the eyepiece. This corrects your own cylindrical aberration without the eyeglass lenses costing contrast and eye distance.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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In your telescope<\/h4>\n\n\n\n

In a telescope with a focal length of 1200 mm, this eyepiece provides approximately 92x magnification with a true field of view of about 1.06 degrees. You can calculate this for your own telescope using the field stop: true field of view = 57.3 x field stop divided by the telescope's focal length.<\/p>\n\n\n\n

The field stop of this model is 22.3 mm. That number, not just the focal length, determines how much of the sky you actually see.<\/p>\n<\/div>\n<\/div>\n\n\n\n

Included<\/h3>\n\n\n\n