{"id":159,"date":"2006-04-29T20:17:37","date_gmt":"2006-04-29T19:17:37","guid":{"rendered":"http:\/\/www.roumazeilles.net\/news\/en\/wordpress\/2006\/04\/29\/only-f56-for-auto-focus\/"},"modified":"2006-04-29T11:27:57","modified_gmt":"2006-04-29T10:27:57","slug":"only-f56-for-auto-focus","status":"publish","type":"post","link":"https:\/\/www.roumazeilles.net\/news\/en\/wordpress\/2006\/04\/29\/only-f56-for-auto-focus\/","title":{"rendered":"Only f\/5.6 for auto-focus"},"content":{"rendered":"<p>People keep asking a simple question: &#8220;why do my expensive camera fail to auto-focus when I plug my tele-lens into a 2x converter?&#8221;. Unfortunately, the answer is pretty simple. Most auto-focus cameras (digital or not) have a AF sensor limited to f\/5.6 detection. If your lens is not opening more than that, the AF is technically impossible (the AF sensor does not see enough to separate details).<\/p>\n<p>So, the f\/8 mirror lenses are out of AF. But also, reasonably priced tele-lenses (like a Sigma 400mm\/5.6 lens) are just at the limit and if you had a tele-converter (1.4x or 2x) you loose some more and lo! it will no longer focus.<\/p>\n<p>Known exceptions:<\/p>\n<ul>\n<li>Canon 1D up to f\/8.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>People keep asking a simple question: &#8220;why do my expensive camera fail to auto-focus when I plug my tele-lens into a 2x converter?&#8221;. Unfortunately, the answer is pretty simple. Most auto-focus cameras (digital or not) have a AF sensor limited to f\/5.6 detection. If your lens is not opening more than that, the AF is [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[32,34,8],"tags":[],"class_list":["post-159","post","type-post","status-publish","format-standard","hentry","category-photo","category-tech","category-use-your-dslr"],"_links":{"self":[{"href":"https:\/\/www.roumazeilles.net\/news\/en\/wordpress\/wp-json\/wp\/v2\/posts\/159","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.roumazeilles.net\/news\/en\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.roumazeilles.net\/news\/en\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.roumazeilles.net\/news\/en\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.roumazeilles.net\/news\/en\/wordpress\/wp-json\/wp\/v2\/comments?post=159"}],"version-history":[{"count":0,"href":"https:\/\/www.roumazeilles.net\/news\/en\/wordpress\/wp-json\/wp\/v2\/posts\/159\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.roumazeilles.net\/news\/en\/wordpress\/wp-json\/wp\/v2\/media?parent=159"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.roumazeilles.net\/news\/en\/wordpress\/wp-json\/wp\/v2\/categories?post=159"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.roumazeilles.net\/news\/en\/wordpress\/wp-json\/wp\/v2\/tags?post=159"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}