{"id":3769,"date":"2020-08-26T00:30:13","date_gmt":"2020-08-25T22:30:13","guid":{"rendered":"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/?page_id=3769"},"modified":"2020-11-02T15:13:55","modified_gmt":"2020-11-02T14:13:55","slug":"la-collimation-dun-schmidt-cassegrain-au-moyen-de-sharpcap-puis-de-metaguide","status":"publish","type":"page","link":"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/dossiers-pratiques\/dossiers-materiels\/la-collimation-dun-schmidt-cassegrain-au-moyen-de-sharpcap-puis-de-metaguide","title":{"rendered":"La collimation d\u2019un Schmidt-Cassegrain au moyen de SharpCap puis de Metaguide"},"content":{"rendered":"<p><strong>La collimation d\u2019un Schmidt-Cassegrain au moyen de SharpCap puis de Metaguide<\/strong><\/p>\n<pre><em><span style=\"color: #808080;\">\u00a9 AXEL VINCENT \/ AVEX 2020<\/span><\/em><\/pre>\n<p>Le grand int\u00e9r\u00eat de Metaguide pour la collimation est sa capacit\u00e9 \u00e0 moyenner en temps r\u00e9el l\u2019image d\u2019une \u00e9toile sur plusieurs secondes. Cela permet de lisser les effets de la turbulence atmosph\u00e9rique et fait apparaitre la figure de diffraction (figure d\u2019Airy) pour finaliser la collimation.<\/p>\n<p>1 \u2013 Utiliser SharpCap pour centrer l\u2019ombre du miroir secondaire sur l\u2019image d\u2019une \u00e9toile fortement d\u00e9focalis\u00e9e\u00a0:<\/p>\n<ul>\n<li>\u2013 Lancer SharpCap et ouvrir la cam\u00e9ra principale (celle qui est au foyer de l\u2019instrument)<\/li>\n<li>\u2013 Centrer une \u00e9toile brillante de pr\u00e9f\u00e9rence proche du zenith pour limiter les effets de la r\u00e9fraction atmosph\u00e9rique et la d\u00e9focaliser fortement. Un cercle noir apparait en son centre\u00a0: c\u2019est l\u2019ombre du miroir secondaire qui doit \u00eatre parfaitement concentrique avec le diam\u00e8tre externe de l\u2019image.<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<p><a href=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Extrafocal_222949-2.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignleft wp-image-3771\" src=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Extrafocal_222949-2.png\" alt=\"\" width=\"500\" height=\"500\" srcset=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Extrafocal_222949-2.png 800w, https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Extrafocal_222949-2-500x500.png 500w, https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Extrafocal_222949-2-768x768.png 768w, https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Extrafocal_222949-2-150x150.png 150w\" sizes=\"auto, (max-width: 500px) 100vw, 500px\" \/><\/a><\/p>\n<ul>\n<li>\u2013 Afficher le r\u00e9ticule qui comporte plusieurs cercles concentriques (\u201ccircle\u201d) et le centrer sur l\u2019\u00e9toile dont on ajuste la d\u00e9focalisation pour que son diam\u00e8tre ext\u00e9rieur co\u00efncide avec un des cercles du r\u00e9ticule (le 4<sup>\u00e8me<\/sup> ou le 5<sup>\u00e8me<\/sup>)<\/li>\n<\/ul>\n<p><a href=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Collimation_SharpCap-2.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignleft size-full wp-image-3770\" src=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Collimation_SharpCap-2.png\" alt=\"\" width=\"1366\" height=\"708\" srcset=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Collimation_SharpCap-2.png 1366w, https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Collimation_SharpCap-2-600x311.png 600w, https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Collimation_SharpCap-2-1200x622.png 1200w, https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Collimation_SharpCap-2-768x398.png 768w\" sizes=\"auto, (max-width: 1366px) 100vw, 1366px\" \/><\/a><\/p>\n<ul>\n<li>\u2013 Si l\u2019ombre du secondaire n\u2019est pas centr\u00e9e, agir sur une des vis de r\u00e9glage du miroir secondaire puis recentrer le r\u00e9ticule sur l\u2019\u00e9toile. R\u00e9p\u00e9ter cette \u00e9tape autant que n\u00e9cessaire jusqu\u2019\u00e0 obtention d\u2019une image concentrique.<\/li>\n<li>\u2013 Utiliser Metaguide pour affiner la collimation\u00a0:\n<ul>\n<li>\u2013 Mettre au point l\u2019image de l\u2019\u00e9toile et r\u00e9gler le gain et le temps d\u2019exposition pour obtenir une luminosit\u00e9 \u00e9lev\u00e9e mais une \u00e9toile non satur\u00e9e. Moyenner sur 5 s (Stack Time). V\u00e9rifier sur la courbe repr\u00e9sentant le profil de luminosit\u00e9 de l\u2019\u00e9toile (en bas \u00e0 gauche de la fen\u00eatre principale).<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p><a href=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Collimation-224200.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignleft size-full wp-image-3777\" src=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Collimation-224200.png\" alt=\"\" width=\"1006\" height=\"609\" srcset=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Collimation-224200.png 1006w, https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Collimation-224200-600x363.png 600w, https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Collimation-224200-768x465.png 768w\" sizes=\"auto, (max-width: 1006px) 100vw, 1006px\" \/><\/a><\/p>\n<ul>\n<li style=\"list-style-type: none;\">\n<ul>\n<li style=\"list-style-type: none;\">\n<ul>\n<li>\u2013 Utiliser un filtre rouge ou mieux un filtre H-alpha pour une obtenir image de diffraction plus lisible. Un zoom de l\u2019\u00e9toile s\u2019affiche en fausses couleurs en bas \u00e0 droite de la fen\u00eatre principale. La ligne rouge du dessus indique que la luminosit\u00e9 de l\u2019\u00e9toile est satur\u00e9e ou trop \u00e9lev\u00e9e. Le point rouge d\u00e9signe la direction du d\u00e9faut de collimation.<\/li>\n<li>\u2013 Agir de nouveau sur les vis de r\u00e9glage du miroir secondaire pour obtenir une figure de diffraction avec des anneaux d\u2019Airy r\u00e9guliers.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p><a href=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/20200630_Collimation.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignleft size-full wp-image-3772\" src=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/20200630_Collimation.png\" alt=\"\" width=\"1050\" height=\"609\" srcset=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/20200630_Collimation.png 1050w, https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/20200630_Collimation-600x348.png 600w, https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/20200630_Collimation-768x445.png 768w\" sizes=\"auto, (max-width: 1050px) 100vw, 1050px\" \/><\/a><\/p>\n<p>Remarque\u00a0: l\u2019aspect de la figure de diffraction varie avec la longueur d\u2019onde de la lumi\u00e8re, l\u2019obstruction ou le F\/D.<\/p>\n<p>Effet de l\u2019obstruction\u00a0:<\/p>\n<p><a href=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Airy_Obstruction.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignleft wp-image-3776\" src=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Airy_Obstruction.png\" alt=\"\" width=\"700\" height=\"554\" srcset=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Airy_Obstruction.png 957w, https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Airy_Obstruction-600x475.png 600w, https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Airy_Obstruction-768x608.png 768w\" sizes=\"auto, (max-width: 700px) 100vw, 700px\" \/><\/a><\/p>\n<p>Effet du F\/D\u00a0:<\/p>\n<p><a href=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Airy_FD.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignleft wp-image-3775\" src=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Airy_FD.png\" alt=\"\" width=\"700\" height=\"554\" srcset=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Airy_FD.png 957w, https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Airy_FD-600x475.png 600w, https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Airy_FD-768x608.png 768w\" sizes=\"auto, (max-width: 700px) 100vw, 700px\" \/><\/a><\/p>\n<p>Effet de la longueur d\u2019onde de la lumi\u00e8re<\/p>\n<p><a href=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Airy_couleur.png\">\u00a0<\/a><a href=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Airy_couleur.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignleft wp-image-3774\" src=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Airy_couleur.png\" alt=\"\" width=\"700\" height=\"554\" srcset=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Airy_couleur.png 957w, https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Airy_couleur-600x475.png 600w, https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Airy_couleur-768x608.png 768w\" sizes=\"auto, (max-width: 700px) 100vw, 700px\" \/><\/a><\/p>\n<p><a href=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Airy_400-650nm-2.png\"><img loading=\"lazy\" decoding=\"async\" class=\"alignleft wp-image-3773\" src=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Airy_400-650nm-2.png\" alt=\"\" width=\"700\" height=\"554\" srcset=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Airy_400-650nm-2.png 957w, https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Airy_400-650nm-2-600x475.png 600w, https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-content\/uploads\/2020\/08\/Airy_400-650nm-2-768x608.png 768w\" sizes=\"auto, (max-width: 700px) 100vw, 700px\" \/><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>La collimation d\u2019un Schmidt-Cassegrain au moyen de SharpCap puis de Metaguide \u00a9 AXEL VINCENT \/ AVEX 2020 Le grand int\u00e9r\u00eat<\/p>\n<p><a href=\"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/dossiers-pratiques\/dossiers-materiels\/la-collimation-dun-schmidt-cassegrain-au-moyen-de-sharpcap-puis-de-metaguide\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\">La collimation d\u2019un Schmidt-Cassegrain au moyen de SharpCap puis de Metaguide<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":47,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-3769","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-json\/wp\/v2\/pages\/3769","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-json\/wp\/v2\/comments?post=3769"}],"version-history":[{"count":3,"href":"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-json\/wp\/v2\/pages\/3769\/revisions"}],"predecessor-version":[{"id":3781,"href":"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-json\/wp\/v2\/pages\/3769\/revisions\/3781"}],"up":[{"embeddable":true,"href":"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-json\/wp\/v2\/pages\/47"}],"wp:attachment":[{"href":"https:\/\/www.avex-asso.org\/dossiers\/wordpress\/wp-json\/wp\/v2\/media?parent=3769"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}