{"id":140,"date":"2019-04-05T15:00:04","date_gmt":"2019-04-05T13:00:04","guid":{"rendered":"https:\/\/koustrup.com\/?page_id=140"},"modified":"2021-10-09T16:06:49","modified_gmt":"2021-10-09T14:06:49","slug":"objektivet","status":"publish","type":"page","link":"https:\/\/foto-video.dk\/?page_id=140","title":{"rendered":"2.1: Objektivet"},"content":{"rendered":"<nav aria-label=\"breadcrumbs\">\n            <div class=\"breadcrumb-container theme1\">\n                <ol>\n                    <li><a title=\"Du er her\" href=\"#\"><span>Du er her<\/span><\/a><span class=\"separator\">&gt;&gt;<\/span><\/li>\n                    <\/ol>\n            <\/div>\n        <\/nav>    <script type=\"application\/ld+json\">\n        {\n            \"@context\": \"http:\/\/schema.org\",\n            \"@type\": \"BreadcrumbList\",\n            \"itemListElement\": [\n                 {\n                            \"@type\": \"ListItem\",\n                            \"position\": 1,\n                            \"item\": {\n                                \"@id\": \"#\",\n                                \"name\": \"Du er her\"\n                            }\n                        }\n                                                    ]\n        }\n    <\/script>\n   \n    <script>\n            <\/script>\n\n<hr \/>\n<table style=\"width: 99%; float: center; border: 0px; padding: 5px; margin-right: auto; margin-left: auto;\">\n<tbody>\n<tr>\n<td style=\"text-align: left; vertical-align: middle; width: 36%; border: 0px; padding: 2px;\"><img decoding=\"async\" class=\"size-full wp-image-2661 alignleft\" src=\"https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/objektivet-1-300x207-1.png\" alt=\"\" width=\"300\" height=\"207\" \/><\/td>\n<td style=\"text-align: left; vertical-align: middle; width: 64%; border: 0px; padding: 2px;\" colspan=\"2\">Inden det reflekterede lys fra et objekt danner et billede p\u00e5 sensoren, skal det passere igennem en r\u00e6kke <b>linser<\/b> i objektivet.<br \/>\nVed hj\u00e6lp af linserne <b>samler<\/b> og <b>fokuserer<\/b> objektivet lyset der kommer til sensoren.<br \/>\nLinserne har forskellige funktioner, fx fokusering, kompensere for optiske afvigelser \/ forvr\u00e6ngninger, optisk billedstabilisering o. lign.<br \/>\n<b><\/b><b><\/b><b>Bl\u00e6nden<\/b> (som kan sidde foran\/bag\/mellem linserne) bestemmer <b>hvor meget lys <\/b>der kommer ind i kameraet.<br \/>\nBilledets kvalitet (skarphed, farver og dynamik) afh\u00e6nger af objektivets kvalitet. Et d\u00e5rligt objektiv kan medf\u00f8re uskarpheder, forvr\u00e6ngning, reduceret farvedynamik og i det hele taget en d\u00e5rlig billedkvalitet.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left; vertical-align: middle; border: 0px; padding: 2px;\" colspan=\"3\">\n<hr \/>\n<h3 style=\"text-align: left;\">Br\u00e6ndvidde og billedvinkel:<\/h3>\n<p>Objektivet siges at have en <strong>br\u00e6ndvidde<\/strong> (focal length), som er et udtryk for hvordan objektivet <strong>samler lyset<\/strong> og <strong>fokuserer dette<\/strong>.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left; vertical-align: middle; width: 36%; border: 0px; padding: 2px;\"><img decoding=\"async\" class=\"size-full wp-image-2662 alignleft\" src=\"https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/braendvidde-1-150x150-1.png\" alt=\"\" width=\"150\" height=\"150\" \/><\/td>\n<td style=\"text-align: left; vertical-align: middle; width: 64%; border: 0px; padding: 2px;\" colspan=\"2\">\n<ul>\n<li>I <u>simple<\/u> linse systemer (1-3 linser), vil br\u00e6ndvidden v\u00e6re distancen fra yderste linse til billedplanet (sensoren).<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left; vertical-align: middle; width: 36%; border: 0px; padding: 2px;\"><img decoding=\"async\" class=\"size-medium wp-image-2663 alignleft\" src=\"https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/braendvidde-2-300x150.jpg\" alt=\"\" width=\"300\" height=\"150\" srcset=\"https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/braendvidde-2-300x150.jpg 300w, https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/braendvidde-2.jpg 376w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/td>\n<td style=\"text-align: left; vertical-align: middle; width: 64%; border: 0px; padding: 2px;\" colspan=\"2\">\n<ul>\n<li>N\u00e5r objektivet bliver mere komplekst kan denne definition ikke bruges.<\/li>\n<li>Man bruger da <b>afstanden<\/b> fra det <b>optiske center <\/b>(Point of Convergence \/ Optical Center) til <b>billedplanet<\/b>.<\/li>\n<li>Det optiske center er der hvor lysstr\u00e5lerne krydser hinanden n\u00e5r objektivet er sat til uendelig fokus.<\/li>\n<li>Man kan derfor godt opleve, at et 35 mm objektiv er l\u00e6ngere end et standard 50 mm objektiv.<\/li>\n<\/ul>\n<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left; vertical-align: middle; width: 36%; border: 0px; padding: 2px;\"><img decoding=\"async\" class=\"size-full wp-image-2664 alignleft\" src=\"https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/billedvinkel-1-300x150-1.jpg\" alt=\"\" width=\"300\" height=\"150\" \/><\/td>\n<td style=\"text-align: left; vertical-align: middle; width: 8%; border: 0px; padding: 2px;\"><\/td>\n<td style=\"text-align: left; vertical-align: middle; width: 56%; border: 0px; padding: 2px;\"><b>Billedvinklen<\/b> afh\u00e6nger af <b>objektivet br\u00e6ndvidde <\/b>og <b>sensorens<\/b> fysiske <b>dimension<\/b>.<br \/>\nBem\u00e6rk det er billedvinklen og ikke br\u00e6ndvidden der afh\u00e6nger af sensor st\u00f8rrelse.<br \/>\nEn br\u00e6ndvidde p\u00e5 <strong>50 mm<\/strong> ved en <strong>fuldformat sensor<\/strong> (24mm x 36mm) svarer til <strong>\u00f8jets billedvinkel<\/strong>.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<hr \/>\n<h3 style=\"text-align: left;\">Sammenh\u00e6ngen mellem br\u00e6ndvidde og billedvinkel:<\/h3>\n<p><img decoding=\"async\" class=\"alignnone size-full wp-image-2669\" src=\"https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/Braendvidde-3-1024x731-1.png\" alt=\"\" width=\"1024\" height=\"731\" srcset=\"https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/Braendvidde-3-1024x731-1.png 1024w, https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/Braendvidde-3-1024x731-1-300x214.png 300w, https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/Braendvidde-3-1024x731-1-768x548.png 768w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/p>\n<table style=\"width: 99%; float: center; border: 0px; padding: 5px; margin-right: auto; margin-left: auto;\">\n<tbody>\n<tr>\n<td style=\"text-align: left; vertical-align: middle; border: 0px; padding: 2px;\" colspan=\"3\">\n<hr \/>\n<h3 style=\"text-align: left;\"><b>Crop Factor (besk\u00e6ring \u2013 sensor st\u00f8rrelse):<\/b><\/h3>\n<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left; vertical-align: top; width: 40%; border: 0px; padding: 2px;\"><img decoding=\"async\" class=\"size-full wp-image-2671 alignleft\" src=\"https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/Crop-factor-1-300x150-1.jpg\" alt=\"\" width=\"300\" height=\"150\" \/><\/td>\n<td style=\"text-align: left; vertical-align: top; width: 60%; border: 0px; padding: 2px;\" colspan=\"2\">Med en <b>mindre sensor <\/b>(fx DX &#8211; venstre billede) i billedplanet, vil det kun v\u00e6re en <b>del af <\/b>det dannede <b>billede<\/b> som optages af sensoren.<br \/>\nEn fuldformat (h\u00f8jre billede) sensor g\u00e5r helt ud til kanten, og optager derfor mere af billedfeltet.<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left; vertical-align: top; width: 60%; border: 0px; padding: 2px;\" colspan=\"2\">N\u00e5r man forst\u00f8rrer billedet til, fx 9 x 12 cm \u2013 vil det se ud som DX sensoren har zoomet l\u00e6ngere ind end FX sensoren.Men det er ikke tilf\u00e6ldet \u2013 vi har blot <b>forst\u00f8rret<\/b> DX billedet <b>mere<\/b> end FX billedet \u2013 med (et lille) tab i opl\u00f8sning til f\u00f8lge.<\/td>\n<td style=\"text-align: left; vertical-align: top; width: 40%; border: 0px; padding: 2px;\"><img decoding=\"async\" class=\"wp-image-2726 size-medium alignright\" src=\"https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/Crop-factor-2-300x300.jpg\" alt=\"\" width=\"300\" height=\"300\" srcset=\"https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/Crop-factor-2-300x300.jpg 300w, https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/Crop-factor-2-150x150.jpg 150w, https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/Crop-factor-2.jpg 445w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<table style=\"width: 95%; float: center; border: 0; padding: 15px; margin-right: auto; margin-left: auto;\">\n<tbody>\n<tr>\n<td style=\"width: 50%; border: 0px; padding: 10px; text-align: center;\"><img decoding=\"async\" class=\"wp-image-2676 size-full aligncenter\" src=\"https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/DSC1034-1024x680-1.jpg\" alt=\"\" width=\"1024\" height=\"680\" srcset=\"https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/DSC1034-1024x680-1.jpg 1024w, https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/DSC1034-1024x680-1-300x199.jpg 300w, https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/DSC1034-1024x680-1-768x510.jpg 768w, https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/DSC1034-1024x680-1-272x182.jpg 272w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/>Billede taget med APS-C sensor og 70 mm objektiv<\/td>\n<td style=\"width: 50%; border: 0px; padding: 10px; text-align: center;\"><img decoding=\"async\" class=\"size-full wp-image-2677 aligncenter\" src=\"https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/DSC0502-1024x683-1.jpg\" alt=\"\" width=\"1024\" height=\"683\" srcset=\"https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/DSC0502-1024x683-1.jpg 1024w, https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/DSC0502-1024x683-1-300x200.jpg 300w, https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/DSC0502-1024x683-1-768x512.jpg 768w, https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/DSC0502-1024x683-1-272x182.jpg 272w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/>Billede taget med fuldformat sensor og 70 mm objektiv<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<hr \/>\n<h3 style=\"text-align: left;\">Br\u00e6ndvidde (fokal l\u00e6ngde):<\/h3>\n<p><img decoding=\"async\" class=\"size-full wp-image-2679 aligncenter\" src=\"https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/braendvidde-4.jpg\" alt=\"\" width=\"762\" height=\"534\" srcset=\"https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/braendvidde-4.jpg 762w, https:\/\/foto-video.dk\/wp-content\/uploads\/2021\/10\/braendvidde-4-300x210.jpg 300w\" sizes=\"(max-width: 762px) 100vw, 762px\" \/><\/p>\n<p style=\"text-align: center;\">Objektivets br\u00e6ndvidde vil bestemme, hvor t\u00e6t billedet er p\u00e5 motivet (zoom) og billedvinkel.<\/p>\n<p style=\"text-align: center;\">\u00d8jets billedvinkel svarer nogenlunde til et 50 mm objektiv monteret p\u00e5 et FX format kamera.<\/p>\n<hr \/>\n<table style=\"width: 95%; float: center; border: 2px solid black; padding: 15px; margin-right: auto; margin-left: auto;\">\n<tbody>\n<tr>\n<th style=\"text-align: center; vertical-align: middle; width: 50%; border: 1px solid black; padding: 15px;\">\n<h3>Br\u00e6ndvidder<\/h3>\n<\/th>\n<th style=\"text-align: center; vertical-align: middle; width: 50%; border: 1px solid black; padding: 15px;\">\n<h3>billedvinkel<\/h3>\n<p><strong>(svarer til fuldformat sensor)<\/strong><\/th>\n<\/tr>\n<tr>\n<td style=\"text-align: left; vertical-align: middle; width: 50%; border: 1px solid black; padding: 15px;\">Under 14 mm<\/td>\n<td style=\"text-align: left; vertical-align: middle; width: 50%; border: 1px solid black; padding: 15px;\">Ekstrem vidvinkel (fiske\u00f8je)<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left; vertical-align: middle; width: 50%; border: 1px solid black; padding: 15px;\">14-35 mm<\/td>\n<td style=\"text-align: left; vertical-align: middle; width: 50%; border: 1px solid black; padding: 15px;\">Vidvinkel<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left; vertical-align: middle; width: 50%; border: 1px solid black; padding: 15px;\">35-70 mm (50 mm)<\/td>\n<td style=\"text-align: left; vertical-align: middle; width: 50%; border: 1px solid black; padding: 15px;\">Normalobjektiv<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left; vertical-align: middle; width: 50%; border: 1px solid black; padding: 15px;\">70-150 mm<\/td>\n<td style=\"text-align: left; vertical-align: middle; width: 50%; border: 1px solid black; padding: 15px;\">Medium tele<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left; vertical-align: middle; width: 50%; border: 1px solid black; padding: 15px;\">150-600 mm<\/td>\n<td style=\"text-align: left; vertical-align: middle; width: 50%; border: 1px solid black; padding: 15px;\">Tele<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left; vertical-align: middle; width: 50%; border: 1px solid black; padding: 15px;\">600+ mm<\/td>\n<td style=\"text-align: left; vertical-align: middle; width: 50%; border: 1px solid black; padding: 15px;\">Ekstrem tele<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>P\u00e5 kompakt kameraer kan man v\u00e6lge W for vidvinkel og T for tele. Alternativt er der en zoom funktion.<br \/>\nDette er <b>KUN<\/b> g\u00e6ldende for <b>optisk zoom<\/b>, digital zoom er reelt en forst\u00f8rrelse af sensorens midterste omr\u00e5de og virker ikke s\u00e6rlig godt.<\/p>\n<p>P\u00e5 spejlrefleks og systemkameraer vil man normalt skulle dreje\/skubbe p\u00e5 selve objektive, for at \u00e6ndre br\u00e6ndvidde (zoom).<\/p>\n<hr \/>\n<h3 style=\"text-align: left;\">Objektivet \u2013 forvr\u00e6ngning \/ afvigelse:<\/h3>\n<p>I <strong>alle objektiver<\/strong> vil der forekomme forskellige former for <strong>optisk forvr\u00e6ngning eller afvigelse<\/strong> (optical aberration).<br \/>\nMan taler om \u2013<\/p>\n<ul>\n<li><strong><a href=\"https:\/\/foto-video.dk\/?page_id=197\">Sl\u00f8ring (Defocus) \u2013 ude af fokus<\/a><\/strong><\/li>\n<li><a href=\"https:\/\/foto-video.dk\/?page_id=204\"><strong>Styrtende linjer (Tilt)<\/strong><\/a><\/li>\n<li><a href=\"https:\/\/foto-video.dk\/?page_id=210\"><strong>Sf\u00e6risk forvr\u00e6ngning (Spherical aberration)<\/strong><\/a><\/li>\n<li><a href=\"https:\/\/foto-video.dk\/?page_id=216\"><strong>Astigmatisme (astigmatism)<\/strong><\/a><\/li>\n<li><a href=\"https:\/\/foto-video.dk\/?page_id=222\"><strong>Comatisk forvr\u00e6ngning (comatic aberration)<\/strong><\/a><\/li>\n<li><a href=\"https:\/\/foto-video.dk\/?page_id=227\"><strong>Optisk forvr\u00e6ngning (optical distortion)<\/strong><\/a><\/li>\n<li><a href=\"https:\/\/foto-video.dk\/?page_id=240\"><strong>Petzval feltkrumning (Petzval field curvature)<\/strong><\/a><\/li>\n<li><a href=\"https:\/\/foto-video.dk\/?page_id=244\"><strong>Kromatisk afvigelse (chromatic aberration)<\/strong><\/a><\/li>\n<li><a href=\"https:\/\/foto-video.dk\/?page_id=235\"><strong>Vignetter (Vignetting)<\/strong><\/a><\/li>\n<li><a href=\"https:\/\/foto-video.dk\/?page_id=255\"><strong>Blooming<\/strong><\/a><\/li>\n<\/ul>\n<p>De fleste af disse forvr\u00e6ngninger (optiske fejl) kan man kompensere for i opbygningen af objektivet.<br \/>\nI hvor stor udstr\u00e6kning det er lykkedes af kompensere kommer direkte til udtryk i objektivets kvalitet (og pris).<\/p>\n<hr \/>\n","protected":false},"excerpt":{"rendered":"<p>Inden det reflekterede lys fra et objekt danner et billede p\u00e5 sensoren, skal det passere igennem en r\u00e6kke linser i objektivet. Ved hj\u00e6lp af linserne samler og fokuserer objektivet lyset der kommer til sensoren. Linserne har forskellige funktioner, fx fokusering, kompensere for optiske afvigelser \/ forvr\u00e6ngninger, optisk billedstabilisering o. lign. Bl\u00e6nden (som kan sidde foran\/bag\/mellem [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":112,"menu_order":10,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-140","page","type-page","status-publish","hentry","post"],"_links":{"self":[{"href":"https:\/\/foto-video.dk\/index.php?rest_route=\/wp\/v2\/pages\/140","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/foto-video.dk\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/foto-video.dk\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/foto-video.dk\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/foto-video.dk\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=140"}],"version-history":[{"count":36,"href":"https:\/\/foto-video.dk\/index.php?rest_route=\/wp\/v2\/pages\/140\/revisions"}],"predecessor-version":[{"id":2729,"href":"https:\/\/foto-video.dk\/index.php?rest_route=\/wp\/v2\/pages\/140\/revisions\/2729"}],"up":[{"embeddable":true,"href":"https:\/\/foto-video.dk\/index.php?rest_route=\/wp\/v2\/pages\/112"}],"wp:attachment":[{"href":"https:\/\/foto-video.dk\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=140"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}