{"id":132,"date":"2022-04-29T14:00:16","date_gmt":"2022-04-29T13:00:16","guid":{"rendered":"http:\/\/mollet-cornelis.be\/wordpress2\/?p=132"},"modified":"2023-09-06T10:23:08","modified_gmt":"2023-09-06T09:23:08","slug":"300mm-dual-focus-telescope","status":"publish","type":"post","link":"http:\/\/mollet-cornelis.be\/wordpress2\/2022\/04\/29\/300mm-dual-focus-telescope\/","title":{"rendered":"300mm dual focus telescope"},"content":{"rendered":"\n

Lichtenknecker optics 300mm dual focus telescope: Newton or Cassegrain<\/strong><\/h2>\n\n\n\n

We’re still trying to figure out all the details of this telescope, at this point we only know it’s diameter (300mm), focal length of the primary mirror (approx. 1620mm, according to our measurements and the numbers written on the back of the primary mirror) and the fact that both secondary mirrors are present AND can be installed. But no focusing mechanism available, neither at the Newtonian focus nor at the Cassegrain focus.<\/p>\n\n\n\n

The mirrors are still in great shape, it seems the telescope tube stayed always carefully closed while packed inside the house.<\/p>\n\n\n\n

Update 09\/2023: I was able to determine the focal length of the Cassegrain-configuration<\/strong> (by measuring the size of the Solar disc in the focal plane! Be careful if you try this at home :-)) => approximately 7.700mm<\/strong> (+\/- 200mm). So it seems to be an f\/25 – or slightly longer.<\/p>\n\n\n\n

<\/p>\n\n\n\n

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The primary mirror (before cleaning) in its cell, + the (very) long baffle<\/figcaption><\/figure>\n\n\n\n
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After cleaning, with only a little dust (telescope mirrors are great dust-magnets :-))<\/figcaption><\/figure>\n\n\n\n
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Mind you, it’s heavy! Contrary to modern telescopes, this one has a very thick mirror (1\/6th of its diameter). The main advantage: one doesn’t need a complicated mirror-cell… <\/figcaption><\/figure>\n\n\n\n
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Radius of curvature: 3240 mm (so approx. 1620mm focal length). But we couldn’t figure out (yet) what the other code stands for…<\/figcaption><\/figure>\n\n\n\n
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The Newtonian secondary<\/figcaption><\/figure>\n\n\n\n
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Lichtenknecker optics 300mm dual focus telescope: Newton or Cassegrain We’re still trying to figure out all the details of this telescope, at this point we only know it’s diameter (300mm), focal length of the primary mirror (approx. 1620mm, according to our measurements and the numbers written on the back of the primary mirror) and the […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-132","post","type-post","status-publish","format-standard","hentry","category-uncategorised"],"_links":{"self":[{"href":"http:\/\/mollet-cornelis.be\/wordpress2\/wp-json\/wp\/v2\/posts\/132","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/mollet-cornelis.be\/wordpress2\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/mollet-cornelis.be\/wordpress2\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/mollet-cornelis.be\/wordpress2\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/mollet-cornelis.be\/wordpress2\/wp-json\/wp\/v2\/comments?post=132"}],"version-history":[{"count":7,"href":"http:\/\/mollet-cornelis.be\/wordpress2\/wp-json\/wp\/v2\/posts\/132\/revisions"}],"predecessor-version":[{"id":359,"href":"http:\/\/mollet-cornelis.be\/wordpress2\/wp-json\/wp\/v2\/posts\/132\/revisions\/359"}],"wp:attachment":[{"href":"http:\/\/mollet-cornelis.be\/wordpress2\/wp-json\/wp\/v2\/media?parent=132"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/mollet-cornelis.be\/wordpress2\/wp-json\/wp\/v2\/categories?post=132"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/mollet-cornelis.be\/wordpress2\/wp-json\/wp\/v2\/tags?post=132"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}