{"id":9710,"date":"2015-05-01T07:49:48","date_gmt":"2015-05-01T07:49:48","guid":{"rendered":"https:\/\/groupeastronomiespa.be\/astrogas\/solar-imaging-increasing-f-d\/"},"modified":"2025-06-14T12:29:38","modified_gmt":"2025-06-14T10:29:38","slug":"solar-imaging-increasing-f-d","status":"publish","type":"post","link":"https:\/\/groupeastronomiespa.be\/astrogas\/solar-imaging-increasing-f-d\/","title":{"rendered":"Solar imaging – Increasing F\/D"},"content":{"rendered":"

English test later in italic<\/p>\n

\"\"<\/a><\/p>\n

En imagerie Ha avec \u00e9talon arri\u00e8re, au plus le rapport F\/D est \u00e9lev\u00e9 \u00e0 l’entr\u00e9e du Fabry-Perrot, au mieux.
\nVoici un test. Le tirage du r\u00e9ducteur de focale est adapt\u00e9 de mani\u00e8re \u00e0 avoir un champ \u00e9quivalent.<\/p>\n

A gauche, le rapport F\/D \u00e0 l’entr\u00e9e de l’\u00e9talon est d’environ 32 (f8 x 4)
\nA droite, le rapport F\/D \u00e0 l’entr\u00e9e de l’\u00e9talon est d’environ 55 (f8 x1.7 x 4)<\/p>\n

Le r\u00e9sultat n’est pas celui attendu. J’avais d\u00e9j\u00e0 fait un test \u00e9quivalent, avec un PST modifi\u00e9. Le r\u00e9sultat allait dans la m\u00eame direction \ud83d\ude41 .<\/p>\n

Les deux circuits optiques ne sont pas les m\u00eames, et ce n\u2019est pas vraiment comparable.
\n – A F\/D 32, une t\u00e9l\u00e9centrique est en jeu, l\u2019optique id\u00e9ale pour l\u2019imagerie Ha. M\u00eame si cette t\u00e9l\u00e9centrique n’est pas calcul\u00e9e pour cette optique particuli\u00e8re, elle donne satisfaction.<\/p>\n

– A F\/D 55, une sorte de barlow est introduite dans le circuit. On d\u00e9vie certainement du sch\u00e9ma id\u00e9al.<\/p>\n

Il faudrait recommencer ce test avec deux t\u00e9l\u00e9centriques \u00ab\u00a0pures\u00a0\u00bb.
\nPour le fun, voici l’image captur\u00e9e \u00e0 F\/D55, apr\u00e8s traitement:<\/p>\n

\"\"<\/a>

IDL TIFF file<\/p><\/div>\n

———————————————————————————————————————————–
\nIn Ha imaging with rear etalon, the higher the F\/D ratio at the entry of the Fabry-Perrot, the beter.<\/p>\n

Here, a test. The distance between the focal reducer and the CCD is adjusted to have an equivalent field in both cases.<\/p>\n

On the left, the F\/D at the entry of the etalon is about 32 (f8 x 4)
\nOn the right, the F\/D at the entry of the etalon is about 55 (f8 X1.7 x 4)<\/p>\n

The result is not the one expected. I had already made a similar test with a modified PST. The result was in the same direction \ud83d\ude41 .<\/p>\n

The two optical circuits are not the same, and it’s not really comparable.
\n – At F\/D 32, a telecentric, the ideal optical magnification lens for Ha, is used. Although this telecentric is not calculated for this particular optic, it gives satisfaction.<\/p>\n

– At F\/D 55, a sort of barlow is introduced into the circuit. We certainly deviate from the ideal scheme, not being purely telecentric at the etalon.<\/p>\n

This test should be repeated with two \u2018pure\u2019 telecentric systems.<\/p>\n

For the fun, here is the pic captured at F\/D55, after treatment.
\n<\/em><\/p>\n

\"\"<\/a>

IDL TIFF file<\/p><\/div>
\n———————————————————————————————————————————–
\nAlexandre
\n2015-Apr-08
\nFrance-South
\nERF
\nTaka FS128 f8
\nBaader Glaspath-Corrector x1.7 (Optional)
\nBaader TZ4
\nSolar Spectrum 0.3A
\nFocal reducer
\nExtension (Optional)
\nBasler ACA1300 <\/p>\n\n\n

\n \n
\n \n
\n
\n \n\n
<\/div>\n <\/div>\n
\n \n\n
<\/div>\n <\/div>\n
\n \n\n
<\/div>\n <\/div>\n
\n \n\n
<\/div>\n <\/div>\n
\n \n\n
<\/div>\n <\/div>\n
\n \n\n
<\/div>\n <\/div>\n
\n \n\n
<\/div>\n <\/div>\n
\n \n\n
<\/div>\n <\/div>\n
\n \n\n
<\/div>\n <\/div>\n
\n \n\n
<\/div>\n <\/div>\n <\/div>\n \n
\n
\n \n\n
<\/div>\n <\/div>\n
\n \n\n
<\/div>\n <\/div>\n
\n \n\n
<\/div>\n <\/div>\n
\n \n\n
<\/div>\n <\/div>\n
\n \n\n
<\/div>\n <\/div>\n
\n \n\n
<\/div>\n <\/div>\n
\n \n\n
<\/div>\n <\/div>\n
\n \n\n
<\/div>\n <\/div>\n
\n \n\n
<\/div>\n <\/div>\n
\n \n\n
<\/div>\n <\/div>\n <\/div>\n<\/div>\n \n\n
\n Veuillez voter<\/span>\n <\/div>\n <\/div>\n","protected":false},"excerpt":{"rendered":"

English test later in italic En imagerie Ha avec \u00e9talon arri\u00e8re, au plus le rapport F\/D est \u00e9lev\u00e9 \u00e0 l’entr\u00e9e du Fabry-Perrot, au mieux. Voici un test. Le tirage du r\u00e9ducteur de focale est adapt\u00e9 de mani\u00e8re \u00e0 avoir un champ \u00e9quivalent. A gauche, le rapport F\/D \u00e0 l’entr\u00e9e de l’\u00e9talon est d’environ 32 (f8 […]<\/p>\n","protected":false},"author":16,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[3],"tags":[],"class_list":["post-9710","post","type-post","status-publish","format-standard","hentry","category-astrobricolage"],"_links":{"self":[{"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/posts\/9710","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/users\/16"}],"replies":[{"embeddable":true,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/comments?post=9710"}],"version-history":[{"count":3,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/posts\/9710\/revisions"}],"predecessor-version":[{"id":14826,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/posts\/9710\/revisions\/14826"}],"wp:attachment":[{"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/media?parent=9710"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/categories?post=9710"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/groupeastronomiespa.be\/astrogas\/wp-json\/wp\/v2\/tags?post=9710"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}