{"id":16724,"date":"2026-09-18T19:38:36","date_gmt":"2026-09-18T17:38:36","guid":{"rendered":"https:\/\/deep-space-astronomy.ch\/?post_type=product&#038;p=16724"},"modified":"2026-10-31T08:48:10","modified_gmt":"2026-10-31T07:48:10","slug":"tele-vue-ethos-21-mm","status":"publish","type":"product","link":"https:\/\/deep-space-astronomy.ch\/en\/product\/tele-vue-ethos-21-mm\/","title":{"rendered":"Ethos 21 mm Tele Vue \u2013 100\u00b0 Eyepiece"},"content":{"rendered":"<div class=\"product\"><div class=\"product\"><h3>Ethos 21 mm Eyepiece: Key Features<\/h3>\n<p>The <strong>Ethos 21 mm Tele Vue<\/strong> is a 21-mm astronomical eyepiece offering an apparent field of view of <strong>100\u00b0<\/strong>. It mounts on a 2-inch slip-on adapter and has an eye relief of 15 mm. This configuration is worth considering for star fields and extended deep-sky objects, depending on your telescope's focal length.<\/p>\n<h3>What is this model best suited for?<\/h3>\n<p>The Ethos series is designed for observers who want a very wide field of view around the subject. The Ethos SX models offer an apparent field of view of 110\u00b0, compared to 100\u00b0 for the other Ethos models. This apparent field of view should not be confused with the actual field of view visible through your telescope.<\/p>\n<ul>\n<li>Effective aperture of 36.2 mm: actual field of view similar to that of the Panoptic 35 mm, with a smaller exit pupil for the same instrument.<\/li>\n<\/ul>\n<h3>Technical specifications<\/h3>\n<table style=\"width:100%;border-collapse:collapse\">\n<tbody>\n<tr>\n<th scope=\"row\">Manufacturer reference<\/th>\n<td>ETH-21.0<\/td>\n<\/tr>\n<tr>\n<th scope=\"row\">Family<\/th>\n<td>Ethos<\/td>\n<\/tr>\n<tr>\n<th scope=\"row\">Focal length<\/th>\n<td>21 mm<\/td>\n<\/tr>\n<tr>\n<th scope=\"row\">Apparent field<\/th>\n<td>100\u00b0<\/td>\n<\/tr>\n<tr>\n<th scope=\"row\">Flow<\/th>\n<td>2 inches<\/td>\n<\/tr>\n<tr>\n<th scope=\"row\">Eye Discharge<\/th>\n<td>15 mm<\/td>\n<\/tr>\n<tr>\n<th scope=\"row\">Field diaphragm<\/th>\n<td>36.2 mm<\/td>\n<\/tr>\n<tr>\n<th scope=\"row\">Weight<\/th>\n<td>2.25 lb \/ 36 oz<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3>Frequently asked questions<\/h3>\n<p><strong>What is the magnification with this eyepiece?<\/strong><br \/>With a telescope that has a focal length of 1,000 mm, this eyepiece provides approximately 48\u00d7 magnification. The magnification is calculated by dividing the telescope's focal length by that of the eyepiece.<\/p>\n<p><strong>Is it compatible with my telescope?<\/strong><br \/>It requires a 2-inch eyepiece holder or a 2-inch right-angle mirror. It cannot be inserted directly into a 1.25-inch mount. Also check that it is securely fastened and properly balanced.<\/p>\n<p><strong>Can you observe things with glasses?<\/strong><br \/>The specified eye relief is 15 mm. Comfort when wearing glasses also depends on their shape and the position of the eye; trying them on is always better than relying on a universal guarantee. The Tele Vue chart indicates DIOPTRX compatibility; this astigmatism corrector is optional.<\/p>\n<p><strong>Is the apparent field the field visible in the sky?<\/strong><br \/>No. The apparent field of view of 100\u00b0 describes the view through the eyepiece. The actual field of view depends on the telescope; the field stop of 36.2 mm is the value to use to calculate it.<\/p>\n<h3>Before Ordering<\/h3>\n<p>Check the focus travel, the focusing range, the weight your mount can support, and the compatibility of filters or correctors. The product offered is a Tele Vue Ethos 21 mm eyepiece; the accessories listed are optional. The availability shown reflects our supplier\u2019s status at the time of the last check and does not indicate a reserved quantity.<\/p>\n<p>Features and Compatibility: <a href=\"https:\/\/www.televue.com\/engine\/TV3b_page.asp?ID=20&amp;Tab=EP_ETH-21.0\" target=\"_blank\" rel=\"noopener\">Tele Vue ETH-21.0 Official Product Sheet<\/a>.<\/p>\n<\/div><\/div>","protected":false},"excerpt":{"rendered":"<p>Ethos 21 mm Tele Vue: 21 mm focal length, 100\u00b0 apparent field of view, 2-inch thread, and 15 mm eye relief. Part number ETH-21.0.<\/p>","protected":false},"featured_media":16723,"comment_status":"open","ping_status":"closed","template":"","meta":[],"product_brand":[629],"product_cat":[695,833,368],"product_tag":[],"class_list":["post-16724","product","type-product","status-publish","has-post-thumbnail","product_brand-televue","product_cat-oculaires-et-smart-oculaires","product_cat-en-stock","product_cat-visuel","first","instock","taxable","shipping-taxable","purchasable","product-type-simple"],"_links":{"self":[{"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/product\/16724","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/types\/product"}],"replies":[{"embeddable":true,"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/comments?post=16724"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/media\/16723"}],"wp:attachment":[{"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/media?parent=16724"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/product_brand?post=16724"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/product_cat?post=16724"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/deep-space-astronomy.ch\/en\/wp-json\/wp\/v2\/product_tag?post=16724"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}