{"id":1350,"date":"2019-06-30T15:40:42","date_gmt":"2019-06-30T13:40:42","guid":{"rendered":"https:\/\/koustrup.com\/?page_id=1350"},"modified":"2022-09-01T15:44:00","modified_gmt":"2022-09-01T13:44:00","slug":"eksponeringsvaerdi-ev","status":"publish","type":"page","link":"https:\/\/foto-video.dk\/?page_id=1350","title":{"rendered":"3.2: Eksponeringsv\u00e6rdi (EV)"},"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<div style=\"color: black;\">\n<p>Eksponeringsv\u00e6rdi er et begreb, som fort\u00e6ller noget om sammenh\u00e6ngen mellem bl\u00e6nde og lukker i forhold til, hvor meget lys der er og &#8216;filmens&#8217; (sensorens) f\u00f8lsomhed over for lys (ISO-v\u00e6rdi).<\/p>\n<p><!-- Tabel inden i tabellen -->Man kan udregne eksponeringsv\u00e6rdien (EV) for lys og ISO-v\u00e6rdien (se nedenfor), og man kan udregne eksponeringsv\u00e6rdien (EV) for bl\u00e6nde-lukker kombinationer (se nedenfor).<\/p>\n<p>De to v\u00e6rdier skal v\u00e6re lig med hinanden, for at man f\u00e5r et korrekt eksponeret billede.<\/p>\n<p>EV skal ikke opfattes som en absolut v\u00e6rdi, men mere som en form for &#8216;mellemregning&#8217; eller relativt resultat.<\/p>\n<hr \/>\n<h3 style=\"text-align: center;\">Eksponeringsv\u00e6rdi af Lysm\u00e6ngde og ISO-v\u00e6rdi.<\/h3>\n<table style=\"width: 100%; float: center; border: 0; padding: 5px; margin-right: auto; margin-left: auto;\">\n<tbody>\n<tr>\n<td style=\"vertical-align: top; border: 0; padding: 2px; text-align: center;\" colspan=\"2\"><a href=\"https:\/\/koustrup.com\/wp-content\/uploads\/2019\/08\/Eksponering06.png\"><img decoding=\"async\" class=\"aligncenter wp-image-1432 size-full\" src=\"https:\/\/koustrup.com\/wp-content\/uploads\/2019\/08\/Eksponering06.png\" alt=\"\" width=\"1214\" height=\"660\" \/><\/a><\/p>\n<p style=\"text-align: left;\">N\u00e5r man udregner ovenst\u00e5ende v\u00e6rdi vil man f\u00e5 et tal, der er uden enheder.<\/p>\n<p>&nbsp;<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left; vertical-align: top; width: 50%; border: 0; padding: 2px;\"><a href=\"https:\/\/koustrup.com\/wp-content\/uploads\/2019\/08\/eksponering07.png\"><br \/>\n<img decoding=\"async\" class=\"wp-image-1434 aligncenter\" src=\"https:\/\/koustrup.com\/wp-content\/uploads\/2019\/08\/eksponering07-263x300.png\" alt=\"\" width=\"320\" height=\"365\" \/><br \/>\n<\/a><\/td>\n<td style=\"text-align: left; vertical-align: top; border: 0; padding: 2px;\">N\u00e5r vi <strong>fordobler<\/strong> lysf\u00f8lsomheden (fx g\u00e5r fra ISO 100 til ISO 200), svarer det til, at vi l\u00e6gger en (<strong>+1<\/strong>) til eksponeringsv\u00e6rdien (<strong>EV<\/strong>).<\/p>\n<p>Man siger ogs\u00e5, at man g\u00e5r <strong>et stop op<\/strong> for hvert trin man <strong>fordobler f\u00f8lsomheden<\/strong>.<\/p>\n<p>N\u00e5r man fordobler lysf\u00f8lsomheden, skal der halvt s\u00e5 meget lys til at eksponere sensoren korrekt.<\/p>\n<p>Tilsvarende, hvis vi <strong>halverer lysf\u00f8lsomheden<\/strong> (fx g\u00e5r fra\u00a0 ISO 400 til ISO 200), skal man tr\u00e6kke en (<strong>-1<\/strong>) fra eksponeringsv\u00e6rdien (<strong>EV<\/strong>).<\/p>\n<p>Man siger da, at man g\u00e5r <strong>et stop ned<\/strong> for hvert trin vi <strong>halverer lysf\u00f8lsomheden<\/strong>.<\/p>\n<p>N\u00e5r man halverer lysf\u00f8lsomheden, skal man bruge dobbelt s\u00e5 meget lys til eksponere sensoren korrekt.<\/p>\n<p>&nbsp;<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left; vertical-align: top; border: 0; padding: 2px;\" colspan=\"2\">\n<table style=\"width: 100%; float: center; border: 0; padding: 5px; margin-right: auto; margin-left: auto;\">\n<tbody>\n<tr>\n<td style=\"text-align: left; vertical-align: top; width: 75%; border: 0; padding: 2px;\"><a href=\"https:\/\/koustrup.com\/wp-content\/uploads\/2019\/08\/eksponering08.png\"><img decoding=\"async\" class=\" wp-image-1440 aligncenter\" src=\"https:\/\/koustrup.com\/wp-content\/uploads\/2019\/08\/eksponering08-300x191.png\" alt=\"\" width=\"504\" height=\"321\" \/><\/a><\/td>\n<td style=\"text-align: left; vertical-align: top; border: 0; padding: 2px;\"><a href=\"https:\/\/koustrup.com\/wp-content\/uploads\/2019\/08\/eksponering09.png\"><img decoding=\"async\" class=\"alignleft size-medium wp-image-1442\" src=\"https:\/\/koustrup.com\/wp-content\/uploads\/2019\/08\/eksponering09-194x300.png\" alt=\"\" width=\"194\" height=\"300\" \/><br \/>\n<\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>P\u00e5 grafen (udregnet efter formlen) kan man se, at en <strong>fordobling<\/strong> af <strong>lysf\u00f8lsomheden<\/strong> ved <strong>samme lysstyrke<\/strong> vil betyde at EV for\u00f8ges med en (<strong>+1 EV<\/strong>).<\/p>\n<p>&nbsp;<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left; vertical-align: top; width: 50%; border: 0; padding: 2px;\"><a href=\"https:\/\/koustrup.com\/wp-content\/uploads\/2019\/08\/eksponering10.png\"><img decoding=\"async\" class=\" wp-image-1452 aligncenter\" src=\"https:\/\/koustrup.com\/wp-content\/uploads\/2019\/08\/eksponering10-300x202.png\" alt=\"\" \/><\/a><\/td>\n<td style=\"text-align: left; vertical-align: top; border: 0; padding: 2px;\"><strong>Typiske eksponeringsv\u00e6rdier ved ISO 100<\/strong><\/p>\n<p>V\u00e6lges en h\u00f8jere lysf\u00f8lsomhed (fx ISO 400), skal man l\u00e6gge det tilsvarende antal trin (stop op) til de opgivne tal<\/p>\n<p>Fx ISO 100 -&gt; ISO 400 (to stop op \u2013 to trin op)<\/p>\n<p>Gadebelysning, indend\u00f8rs normal belysning, kontorbelysning EV(100) = 6 \u2013 8 bliver til EV(400) = EV(100) + 2 eller EV = 8 &#8211; 10<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>&nbsp;<\/p>\n<hr \/>\n<h3 style=\"text-align: center;\">Justering af lyset til sensorens f\u00f8lsomhed<\/h3>\n<p><!-- Tabel inden i tabellen --><\/p>\n<table style=\"width: 95%; float: center; border: 0; padding: 10px; margin-right: auto; margin-left: auto;\">\n<tbody>\n<tr>\n<td style=\"text-align: left; vertical-align: middle; border: 0; padding: 5px;\" colspan=\"2\">Lysm\u00e6ngden der kommer ind til sensoren, skal <strong>justeres<\/strong> til <strong>sensorens f\u00f8lsomhed<\/strong>. Det anvender man<strong> bl\u00e6nde<\/strong> og <strong>lukkerhastighed<\/strong> til.<\/p>\n<p><strong>Samspillet<\/strong> mellem <strong>lukker<\/strong> og <strong>bl\u00e6nde<\/strong>, kan ogs\u00e5 stilles op i formel der beregner en eksponeringsv\u00e6rdi\u00a0<strong>EV<\/strong>.<\/p>\n<p><a href=\"https:\/\/koustrup.com\/wp-content\/uploads\/2019\/08\/eksponering11.png\"><img decoding=\"async\" class=\"aligncenter size-large wp-image-1462\" src=\"https:\/\/koustrup.com\/wp-content\/uploads\/2019\/08\/eksponering11-1024x570.png\" alt=\"\" width=\"1024\" height=\"570\" \/><\/a><\/p>\n<p>For at f\u00e5 den <strong>korrekte eksponering<\/strong>, skal <strong>EV (lys, ISO) <\/strong>v\u00e6re<strong> lig <\/strong>med<strong> EV (bl\u00e6nde, lukker)<\/strong>.<\/p>\n<p>&nbsp;<\/td>\n<\/tr>\n<tr>\n<td style=\"text-align: left; vertical-align: middle; border: 0; padding: 5px;\" colspan=\"2\"><strong>Beregner<\/strong> man <strong>eksponeringsv\u00e6rdien<\/strong> af forskellige <strong>kombinationer bl\u00e6nde<\/strong> og <strong>lukkerhastigheder<\/strong>, f\u00e5r man nedenst\u00e5ende diagram.<\/p>\n<p><a href=\"https:\/\/koustrup.com\/wp-content\/uploads\/2019\/08\/eksponering12.png\"><img decoding=\"async\" class=\"aligncenter size-full wp-image-1466\" src=\"https:\/\/koustrup.com\/wp-content\/uploads\/2019\/08\/eksponering12.png\" alt=\"\" width=\"974\" height=\"635\" \/><\/a><strong>Bem\u00e6rk<\/strong> n\u00e5r vi g\u00e5r et <strong>stop ned<\/strong> (fx f2.8 -&gt; f4 eller 1\/125 -&gt; 1\/250), <strong>for\u00f8ges EV<\/strong> med en (<strong>EV+1<\/strong>).<\/p>\n<p>Dette er et udtryk for at vi <strong>halverer lysm\u00e6ngden<\/strong> der kommer <strong>gennem bl\u00e6nde\/lukker<\/strong> og derfor m\u00e5 <strong>kompensere<\/strong> ved at <strong>fordoble<\/strong> den <strong>omgivende lysm\u00e6ngde<\/strong> eller <strong>fordoble<\/strong> sensorens <strong>f\u00f8lsomhed<\/strong> for at opn\u00e5 <strong>korrekt eksponering<\/strong>.<\/p>\n<p>Ofte er det omgivende <strong>lys konstant<\/strong> og vi kan ikke \u00e6ndre p\u00e5 m\u00e6ngden af lys der er reflekteret fra motivet. <strong>Derimod<\/strong> har vi mulighed for at \u00e6ndre p\u00e5 parametrene <strong>ISO<\/strong> (f\u00f8lsomhed), <strong>bl\u00e6nde<\/strong> og <strong>lukkerhastighed<\/strong>.<\/p>\n<p><strong>Sammenh\u00e6ngen<\/strong> mellem disse tre kan illustreres ved hj\u00e6lp af\u00a0<strong>eksponeringstrekanten<\/strong>.<\/p>\n<p>N\u00e5r vi anvender kameraet p\u00e5 automatisk, beregner kameraets computer alle disse ting for os og indstiller ISO, bl\u00e6nde og lukker til, den efter kamerafabrikantens synspunkt, bedste indstilling af bl\u00e6nde, lukker og ISO.<\/p>\n<p>N\u00e5r vi selv tager kontrol af billedets eksponering, skal vi begynde at arbejde med ovenst\u00e5ende formler og grafer.\u00a0 Selv om vi i dag har avancerede og effektive lommeregnere, vil det jo nok v\u00e6re lidt for meget, at hive den frem, hver gang vi skal skyde en stribe billeder.<\/p>\n<p>S\u00e5 derfor er der udarbejdet en r\u00e6kke hj\u00e6lpemidler vi vil se n\u00e6rmere p\u00e5 (se under relevante menupunkter).<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>Eksponeringsv\u00e6rdi er et begreb, som fort\u00e6ller noget om sammenh\u00e6ngen mellem bl\u00e6nde og lukker i forhold til, hvor meget lys der er og &#8216;filmens&#8217; (sensorens) f\u00f8lsomhed over for lys (ISO-v\u00e6rdi). Man kan udregne eksponeringsv\u00e6rdien (EV) for lys og ISO-v\u00e6rdien (se nedenfor), og man kan udregne eksponeringsv\u00e6rdien (EV) for bl\u00e6nde-lukker kombinationer (se nedenfor). De to v\u00e6rdier skal [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":1264,"menu_order":20,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-1350","page","type-page","status-publish","hentry","post"],"_links":{"self":[{"href":"https:\/\/foto-video.dk\/index.php?rest_route=\/wp\/v2\/pages\/1350","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=1350"}],"version-history":[{"count":3,"href":"https:\/\/foto-video.dk\/index.php?rest_route=\/wp\/v2\/pages\/1350\/revisions"}],"predecessor-version":[{"id":2864,"href":"https:\/\/foto-video.dk\/index.php?rest_route=\/wp\/v2\/pages\/1350\/revisions\/2864"}],"up":[{"embeddable":true,"href":"https:\/\/foto-video.dk\/index.php?rest_route=\/wp\/v2\/pages\/1264"}],"wp:attachment":[{"href":"https:\/\/foto-video.dk\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1350"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}