- \n
- Barlow = \u00ab\u00a0Doubleur\u00a0\u00bb de focale – inventeur: Peter Barlow (1776-1862)<\/li>\n\n\n\n
- Meilleure d\u00e9finition: compl\u00e9ment optique qui modifie la longueur focale d’un instrument –> perte de luminosit\u00e9<\/li>\n<\/ul>\n\n\n\n
BARLOW: 2 lentilles trait\u00e9es MC –> faisceau divergent<\/strong> (risque de d\u00e9formation et vignettage)<\/p>\n\n\n\n
![\"\"](\"http:\/\/astroriom.net\/v2\/wp-content\/uploads\/2023\/11\/barlow_faisceau_divergent.png\")
<\/figure>\n\n\n\nFaisceau transmis par un simple doublet achromatique A (ligne rouge) et par une lentille de Barlow B (ligne verte)<\/em><\/strong><\/strong><\/p>\n\n\n\n
- \n
- Se place entre le t\u00e9lescope et l’oculaire (observation visuelle) ou entre l’instrument et la cam\u00e9ra (plan\u00e9taire) –> imagerie HR<\/li>\n\n\n\n
- Tr\u00e8s recommand\u00e9 pour l’astrophotographie<\/li>\n\n\n\n
- G = 1 + T\/f T: tirage (Si T augmente –> G augmente)<\/strong><\/li>\n\n\n\n
- Gamme de grossissement: 1,3 \u00e0 5x<\/strong><\/li>\n<\/ul>\n\n\n\n
![\"\"](\"http:\/\/astroriom.net\/v2\/wp-content\/uploads\/2023\/11\/barlow_focus.png\")
<\/figure>\n\n\n\n- \n
- Existe aux coulants de 31,75 et 50,6mm (stabilit\u00e9 du montage)<\/li>\n\n\n\n
- Qualit\u00e9 d\u00e9pend du verre utilis\u00e9 (achromatique; ED; triplet apo)<\/li>\n<\/ul>\n\n\n\n
2. T\u00e9l\u00e9convertisseurs<\/u><\/strong><\/p>\n\n\n\n
POWERMATE (Televue): 4 lentilles trait\u00e9es MC –> transmission parall\u00e8le<\/strong><\/p>\n\n\n\n
- \n
- D\u00e9veloppement de la formule optique Barlow –> t\u00e9l\u00e9centriques<\/li>\n\n\n\n
- Contraste renforc\u00e9 (verre \u00e0 index \u00e9lev\u00e9)<\/li>\n\n\n\n
- R\u00e9duction du vignettage<\/li>\n\n\n\n
- Bien adapt\u00e9 aux lunettes en H\u03b1 pour observation solaire<\/li>\n\n\n\n
- Recommand\u00e9 en montage sur les t\u00eates binoculaires<\/li>\n\n\n\n
- Astrophoto: Grandissement \u03b3 respect\u00e9 m\u00eame avec ajout d’accessoires sur train optique (Powermate 2x reste \u00e0 2x quelque soit le tirage final)<\/li>\n<\/ul>\n\n\n\n
![\"\"](\"http:\/\/astroriom.net\/v2\/wp-content\/uploads\/2023\/11\/barlow_focus_2.png\")
<\/figure>\n\n\n\n![\"\"](\"http:\/\/astroriom.net\/v2\/wp-content\/uploads\/2023\/11\/barlow_visuels.png\")
<\/figure>\n\n\n\n– – – – – – – – – –<\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"
Multiplicateur de focale, les lentilles Barlow doublent ou triplent la focale de votre instrument, permettant de grossir plus avec le m\u00eame jeux d’occulaires. Attention, il y a plusieurs limites physiques qui font qu’il n’est pas possible de grossir infiniment :– maximum 2.4 fois le diam\u00eatre de votre lunette ou t\u00e9lescope– plus raisonnablement 1.5 fois le … Lire la suite de Barlow et t\u00e9l\u00e9convertisseurs<\/span><\/a><\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10],"tags":[],"class_list":["post-1205","post","type-post","status-publish","format-standard","hentry","category-premierspas","no-featured-image"],"_links":{"self":[{"href":"https:\/\/astroriom.net\/v2\/index.php?rest_route=\/wp\/v2\/posts\/1205","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/astroriom.net\/v2\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/astroriom.net\/v2\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/astroriom.net\/v2\/index.php?rest_route=\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/astroriom.net\/v2\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1205"}],"version-history":[{"count":1,"href":"https:\/\/astroriom.net\/v2\/index.php?rest_route=\/wp\/v2\/posts\/1205\/revisions"}],"predecessor-version":[{"id":1211,"href":"https:\/\/astroriom.net\/v2\/index.php?rest_route=\/wp\/v2\/posts\/1205\/revisions\/1211"}],"wp:attachment":[{"href":"https:\/\/astroriom.net\/v2\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1205"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/astroriom.net\/v2\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1205"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/astroriom.net\/v2\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1205"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
- Gamme de grossissement: 1,3 \u00e0 5x<\/strong><\/li>\n<\/ul>\n\n\n\n