{"id":1137,"date":"2009-02-08T00:44:33","date_gmt":"2009-02-07T15:44:33","guid":{"rendered":"https:\/\/regex.info\/blog\/2009-02-08\/1137"},"modified":"2013-08-28T14:26:33","modified_gmt":"2013-08-28T05:26:33","slug":"spot-on-camera-metering-basics","status":"publish","type":"post","link":"https:\/\/regex.info\/blog\/2009-02-08\/1137","title":{"rendered":"Spot On: Camera Metering Basics"},"content":{"rendered":"\n\n\n<div class='resize_warning' id='arw1137'>\n<b>NOTE<\/b>: Images with an <img class='raw' width='19' height='18' src='\/i\/s\/red_zoomup.gif'\/> icon next to them have been artificially shrunk to better fit your screen; click the icon to restore them, in place, to their regular size.\n<\/div>\n\n\n<p class='subtle'>(This post is enhanced with JavaScript interaction that is likely lost\nif you're reading this in <span class='nobr'>a news<\/span> aggregator; visit <a class='quiet'  style='color:#666'\nhref=\"\/blog\/2009-02-08\/1137\">the original post<\/a> on my site for the\nproper experience.)<\/p>\n\n<div class='ic tight' style='position:relative; width:702px; margin-bottom:0'>\n\n  <div id='p1137a0'><a name='010859' href=\"\/i\/JF7_010859.jpg\"\n  ><img loading=\"lazy\" decoding=\"async\" src=\"\/i\/JF7_010859_sm.jpg\" width=\"690\" height=\"459\"\nalt=\"Spot Metering For Lowlights target was the head of the guy at left -- Shogunzuka -- Kyoto, Japan -- Copyright 2009 Jeffrey Friedl, https:\/\/regex.info\/blog\/\"\nid=\"i010859\"\ntitle=\"Spot Metering For Lowlights target was the head of the guy at left -- Shogunzuka -- Kyoto, Japan -- Copyright 2009 Jeffrey Friedl, https:\/\/regex.info\/blog\/\"\/><\/a>\n  <br\/><span class=\"camera-info robots-nocontent\"><sup>1<\/sup><big>\/<\/big>160 sec, <span class='f'>f<\/span>\/6.3, ISO 1400 &mdash;\n  <a href=\"\/imageinfo.cgi?url=http%3A%2F%2Fregex.info%2Fi%2FJF7_010859.jpg\">map &amp; image data<\/a> &mdash; <a href=\"\/blog\/proximity\/i\/JF7_010859.jpg\">nearby photos<\/a><\/span>\n  <br\/><span class='caption'>Spot Metering For Lowlights<\/span>\n  <br\/>target was the head of the guy at left\n  <\/div>\n\n  <div id='p1137a1' style='visibility:hidden; position:absolute; top:0; left:0'><a name='010860' href=\"\/i\/JF7_010860.jpg\"\n  ><img loading=\"lazy\" decoding=\"async\" src=\"\/i\/JF7_010860_sm.jpg\" width=\"690\" height=\"459\"\nalt=\"\"\nid=\"i010860\"\/><\/a>\n  <br\/><span class=\"camera-info robots-nocontent\"><sup>1<\/sup><big>\/<\/big>640 sec, <span class='f'>f<\/span>\/6.3, ISO 200 &mdash;\n  <a href=\"\/imageinfo.cgi?url=http%3A%2F%2Fregex.info%2Fi%2FJF7_010860.jpg\">map &amp; image data<\/a> &mdash; <a href=\"\/blog\/proximity\/i\/JF7_010860.jpg\">nearby photos<\/a><\/span>\n  <br\/><span class='caption'>Spot Metering For Highlights<\/span>\n  <br\/>target was the clouds to the right of the sun\n  <\/div>\n<\/div>\n<style type=\"text\/css\">\n.b1137 { padding: 3px 20px; border: solid 2px #333 }\n<\/style>\n<center style='margin-top:10px' class='subtle-less'>Two shots, taken four seconds apart<\/center>\n<center style='margin-top: 10px; margin-bottom:6px'>\n<span id='b1137a0' class='b1137' onmouseover='show1137(\"a\", 0)'>Lowlights<\/span>\n&nbsp;&nbsp;&nbsp;&nbsp;\n<span id='b1137a1'  class='b1137' onmouseover='show1137(\"a\", 1)'>Highlights<\/span>\n<\/center>\n<center>( mouse over <span class='nobr'>a button<\/span> to select the shot )<\/center>\n\n<script type='text\/javascript'>\nfunction show1137(which, num)\n{\n    if (num == 0) {\n       document.getElementById(\"p1137\" + which + \"0\").style.visibility = 'visible';\n       document.getElementById(\"p1137\" + which + \"1\").style.visibility = 'hidden';\n       document.getElementById(\"b1137\" + which + \"0\").style.borderColor = 'red';\n       document.getElementById(\"b1137\" + which + \"1\").style.borderColor = '#333';\n    } else {\n       document.getElementById(\"p1137\" + which + \"1\").style.visibility = 'visible';\n       document.getElementById(\"p1137\" + which + \"0\").style.visibility = 'hidden';\n       document.getElementById(\"b1137\" + which + \"1\").style.borderColor = 'red';\n       document.getElementById(\"b1137\" + which + \"0\").style.borderColor = '#333';\n    }\n}\nshow1137(\"a\", 0);\n<\/script>\n\n<p>Cameras are not nearly as good at capturing <span class='nobr'>a wide<\/span> range of brightnesses\nas our eyes, so <span class='nobr'>a high<\/span> contrast scene that appears fine to our eyes often\nends up with either washed-out highlights or dark, muddy lowlights, like\nthe two shots above.<\/p>\n\n<p>When using automatic exposure metering, most cameras default to trying\nto achieve <span class='nobr'>a balance<\/span> between the two extremes, often by sampling the scene\nacross large areas of the frame. <span class='nobr'>The simplest<\/span> mode is for it to pick an\nexposure that averages the brightness levels seen throughout the frame, but\nthis is apparently not very useful because it's been hidden deep in the\nmenu structure on my camera (Nikon D700).<\/p>\n\n<p>More useful, but still simple, is to balance across the whole frame, but\ngive added weight to the center of the frame. That's what <span class='nobr'>I used<\/span> when\nmaking <a href=\"\/blog\/2009-02-06\/1136\">yesterday's\nshot<\/a>. Frankly, with that scene, <span class='nobr'>I'd expect<\/span> that the center weighting\ndidn't have that much impact compared to an overall averaging, but that's\njust speculation.<\/p>\n\n<p>The most specific kind of exposure metering is <i>spot<\/i>, where you\ntell the camera to calculate the exposure from one small area of the frame.\nThis is useful when you want to ensure the proper exposure for the thing\nyou're spotting, but it's at the expense of caring what the rest of the\nframe ends up as.<\/p>\n\n<p style='margin-top:30px'>Here's another example where for the lowlights <span class='nobr'>I put<\/span> the spot marker on\nthe lady's black coat. Black is dark to begin with (duh!), and facing away from\nthe sunset, all the more so, so the camera really amped up the exposure to\ntry to make the coat bright, and as <span class='nobr'>a result<\/span> everything else is washed out...<\/p>\n\n<div class='ic tight' style='position:relative; width:702px;\nmargin-bottom:0'> <div id='p1137b0'><a name='010893'\nhref=\"\/i\/JF7_010893.jpg\" ><img loading=\"lazy\" decoding=\"async\" src=\"\/i\/JF7_010893_sm.jpg\" width=\"690\" height=\"459\"\nalt=\"Nikon D700 + Nikkor 24 -70mm f\/2.8 @ 38 mm &amp;mdash; 1 \/ 160 sec, f\/5, ISO 5000 &amp;mdash; full exif &amp; map &amp;mdash; nearby photos Spot Metering for Lowlights -- Shogunzuka -- Kyoto, Japan -- Copyright 2009 Jeffrey Friedl, https:\/\/regex.info\/blog\/\"\nid=\"i010893\"\ntitle=\"Nikon D700 + Nikkor 24 -70mm f\/2.8 @ 38 mm &amp;mdash; 1 \/ 160 sec, f\/5, ISO 5000 &amp;mdash; full exif &amp; map &amp;mdash; nearby photos Spot Metering for Lowlights -- Shogunzuka -- Kyoto, Japan -- Copyright 2009 Jeffrey Friedl, https:\/\/regex.info\/blog\/\"\/><\/a> <br\/><span\nclass=\"camera-info robots-nocontent\"><sup>1<\/sup><big>\/<\/big>160 sec, <span class='f'>f<\/span>\/5, ISO\n5000 &mdash; <a\nhref=\"\/imageinfo.cgi?url=http%3A%2F%2Fregex.info%2Fi%2FJF7_010893.jpg\">full\nexif &amp; map<\/a> &mdash; <a\nhref=\"\/blog\/proximity\/i\/JF7_010893.jpg\">nearby\nphotos<\/a><\/span> <br\/><span class='caption'>Spot Metering for Lowlights<\/span>\n<\/div>\n\n<div id='p1137b1' style='visibility:hidden; position:absolute; top:0; left:0'><a name='010894' href=\"\/i\/JF7_010894.jpg\"\n><img loading=\"lazy\" decoding=\"async\" src=\"\/i\/JF7_010894_sm.jpg\" width=\"690\" height=\"459\"\nalt=\"\"\nid=\"i010894\"\/><\/a>\n<br\/><span class=\"camera-info robots-nocontent\"><sup>1<\/sup><big>\/<\/big>800 sec, <span class='f'>f<\/span>\/5, ISO 200 &mdash;\n<a href=\"\/imageinfo.cgi?url=http%3A%2F%2Fregex.info%2Fi%2FJF7_010894.jpg\">map &amp; image data<\/a> &mdash; <a href=\"\/blog\/proximity\/i\/JF7_010894.jpg\">nearby photos<\/a><\/span>\n<br\/><span class='caption'>Spot Metering for Highlights<\/span>\n<\/div>\n\n<\/div>\n<center style='margin-top:10px' class='subtle-less'>Two shots, taken half <span class='nobr'>a second<\/span> apart<\/center>\n<center style='margin-top: 10px; margin-bottom:6px'>\n<span id='b1137b0' class='b1137' onmouseover='show1137(\"b\",0)'>Lowlights<\/span>\n&nbsp;&nbsp;&nbsp;&nbsp;\n<span id='b1137b1'  class='b1137' onmouseover='show1137(\"b\",1)'>Highlights<\/span>\n<\/center>\n<center>( mouse over <span class='nobr'>a button<\/span> to select the shot )<\/center>\n\n<script type='text\/javascript'>\nshow1137(\"b\", 0);\n<\/script>\n\n\n<p>There's no fundamental reason that any of this is required, it's just\nthat technology can't currently deal with these scenes very well. <span class='nobr'>It's just counting<\/span> photons, so how hard can it be? \ud83d\ude42 I'm sure that years from now\nthis dynamic-range problem will all be <span class='nobr'>a quaint<\/span> footnote in the history\nbooks, but until then it's <span class='nobr'>a real,<\/span> practical, problem you face pretty much\nevery time you pick up <span class='nobr'>a camera.<\/span><\/p>\n\n<p>Some people try to use <a\nhref=\"\/blog\/2008-06-18\/840\">HDR techniques<\/a> to combine\nthe detail from multiple shots, but that often ends up looking horribly\nfake because in the end, you still have to squeeze all that dynamic range\nback into the highly-limiting data container called the image file.\nTechnology is just not up to par with our eyes.<\/p>\n\n<p>None of the metering modes I've mentioned so far are the default mode\nfor Nikon cameras. Their default metering mode is called &#8220;Color Matrix II&#8221;,\nand it involves sampling the brightness, color, and subject distance at <span class='nobr'>a\nbazillion<\/span> points across the frame, then comparing that data to <span class='nobr'>a database<\/span>\nof 30,000+ real-world scenes that Nikon must have built up by hand over\nyears. <span class='nobr'>It often<\/span> works pretty well... at least for definitions of &#8220;pretty\nwell&#8221; that have been tempered by the aforementioned limitations in current\ntechnologies.<\/p>\n\n<p>I used that for this shot of the sun heading toward the horizon...<\/p>\n\n<div class='ic'><a name='010896' href=\"\/i\/JF7_010896.jpg\"\n><img loading=\"lazy\" decoding=\"async\" src=\"\/i\/JF7_010896_sm.jpg\" width=\"690\" height=\"459\"\nalt=\"Shogunzuka -- Kyoto, Japan -- Copyright 2009 Jeffrey Friedl, https:\/\/regex.info\/blog\/\"\nid=\"i010896\"\ntitle=\"Shogunzuka -- Kyoto, Japan -- Copyright 2009 Jeffrey Friedl, https:\/\/regex.info\/blog\/\"\/><\/a>\n<br\/><span class=\"camera-info robots-nocontent\">Nikon D700 + Nikkor 70-200mm f\/2.8 @ 200 mm &mdash; <sup>1<\/sup><big>\/<\/big>640 sec, <span class='f'>f<\/span>\/10, ISO 200 &mdash;\n<a href=\"\/imageinfo.cgi?url=http%3A%2F%2Fregex.info%2Fi%2FJF7_010896.jpg\">map &amp; image data<\/a> &mdash; <a href=\"\/blog\/proximity\/i\/JF7_010896.jpg\">nearby photos<\/a><\/span>\n<\/div>\n\n<p id='bugsme'>The thing that perhaps bugs me the most about current limitations in\ntechnology is what happens when things are &#8220;too bright&#8221;. Let's take <span class='nobr'>a look<\/span>\nat the sun as it dipped closer to the mountains, in two heavily-cropped\nshots taken 14 seconds apart...<\/p>\n\n<div class='ic tight' style='position:relative; width:702px; margin-bottom:0'>\n\n  <div id='p1137c0'><a name='010913' href=\"\/i\/JF7_010913.jpg\"\n><img loading=\"lazy\" decoding=\"async\" src=\"\/i\/JF7_010913_sm.jpg\" width=\"690\" height=\"500\"\nalt=\"Shogunzuka -- Kyoto, Japan -- Copyright 2009 Jeffrey Friedl, https:\/\/regex.info\/blog\/\"\nid=\"i010913\"\ntitle=\"Shogunzuka -- Kyoto, Japan -- Copyright 2009 Jeffrey Friedl, https:\/\/regex.info\/blog\/\"\/><\/a>\n<br\/><span class=\"camera-info robots-nocontent\"><sup>1<\/sup><big>\/<\/big>160 sec, <span class='f'>f<\/span>\/10, ISO 280 &mdash;\n<a href=\"\/imageinfo.cgi?url=http%3A%2F%2Fregex.info%2Fi%2FJF7_010913.jpg\">map &amp; image data<\/a> &mdash; <a href=\"\/blog\/proximity\/i\/JF7_010913.jpg\">nearby photos<\/a><\/span>\n  <\/div>\n\n  <div id='p1137c1' style='visibility:hidden; position:absolute; top:0; left:0'><a name='010914' href=\"\/i\/JF7_010914.jpg\"\n><img loading=\"lazy\" decoding=\"async\" src=\"\/i\/JF7_010914_sm.jpg\" width=\"690\" height=\"500\"\nalt=\"\"\nid=\"i010914\"\/><\/a>\n<br\/><span class=\"camera-info robots-nocontent\"><sup>1<\/sup><big>\/<\/big>5000 sec, <span class='f'>f<\/span>\/10, ISO 200 &mdash;\n<a href=\"\/imageinfo.cgi?url=http%3A%2F%2Fregex.info%2Fi%2FJF7_010914.jpg\">map &amp; image data<\/a> &mdash; <a href=\"\/blog\/proximity\/i\/JF7_010914.jpg\">nearby photos<\/a><\/span>\n<\/div><\/div>\n\n<center style='margin-top:10px' class='subtle-less'>Two shots, taken 14 seconds apart<\/center>\n<center style='margin-top: 10px; margin-bottom:6px'>\n<span id='b1137c0' class='b1137' onmouseover='show1137(\"c\",0)'>Standard but Unreal<\/span>\n&nbsp;&nbsp;&nbsp;&nbsp;\n<span id='b1137c1'  class='b1137' onmouseover='show1137(\"c\",1)'>Closer to Real: -5.5EV<\/span>\n<\/center>\n<center>( mouse over <span class='nobr'>a button<\/span> to select the shot )<\/center>\n\n<script type='text\/javascript'>\nshow1137(\"c\", 0);\n<\/script>\n\n<p>The setting sun was not yellow or white, but it ends up yellow and white\nin the picture because its photons totally overwhelm the camera sensor. <span class='nobr'>But just as<\/span> three blades of grass end up at the same height after being run\nover with <span class='nobr'>a mower<\/span> &ndash; even if one might have been short, one tall, and\none very tall &ndash; the parts of the sun that end up white do so because\nall three color channels on the sensor (red, green, and blue &ndash; RGB)\nare overwhelmed. Having, therefor, lost all information about the relative\nstrengths among the color channels, we end up with full-on color in each\nchannel: the digital-image definition of &#8220;white&#8221;.<\/p>\n\n<p>The parts of the sun that are yellowish were less bright, such that only\ntwo channels were overwhelmed (red and green). <span class='nobr'>It's as if<\/span> you have three\nblades of grass, one of which is actually shorter than the mower deck, and\nthus after the two taller ones are cut, you still have no idea about the\nrelative brightness except that the one was shorter than the three. <span class='nobr'>In this case<\/span>, &#8220;blue&#8221; being shorter than &#8220;red\/green&#8221; ends up as &#8220;yellow&#8221;.<\/p>\n\n<p>In an attempt to capture the actual color of the sun, <span class='nobr'>I told the<\/span> camera\nto underexpose the image by 5.5 stops. That means that after it decided\nwhat exposure it though would give it <span class='nobr'>a nice<\/span> result, <span class='nobr'>I instructed<\/span> it to\npick an exposure that registered 45&times; <i>less<\/i> light. When you're\ntalking about photons from the sun, &#8220;less&#8221; is definitely <span class='nobr'>a relative<\/span> term,\nwhich is why it still comes out quite well in the second shot. <span class='nobr'>The point<\/span> of\ndoing this was to end the exposure before the photons overwhelmed all the\ncolor channels, and to at least some extent <span class='nobr'>I succeeded.<\/span> <span class='nobr'>It's as if<\/span> <span class='nobr'>I\nraised<\/span> the mower deck to five feet off the ground: <span class='nobr'>a blade<\/span> of grass 10 feet\nhigh is still chopped down considerably, but even after that, relatively\nspeaking, it's still <span class='nobr'>a lot<\/span> taller than <span class='nobr'>a two<\/span>-inch blade of grass.<\/p>\n\n<p style='margin-top:40px'>Finally, I'll end with <span class='nobr'>a shot<\/span> that has nothing\nto do with the rest of these, except that it was taken at the same time. <span class='nobr'>It's the guy<\/span> silhouetted at the left of <a class='quiet'\nhref=\"\/blog\/2009-02-06\/1136\">yesterday's shot<\/a>.<\/p>\n\n<div class='ic tight'><a name='010924' href=\"\/i\/JF7_010924.jpg\"\n><img loading=\"lazy\" decoding=\"async\" src=\"\/i\/JF7_010924_sm.jpg\" width=\"690\" height=\"459\"\nalt=\"like me, Hoping for a Nice Sunset -- Shogunzuka -- Kyoto, Japan -- Copyright 2009 Jeffrey Friedl, https:\/\/regex.info\/blog\/\"\nid=\"i010924\"\ntitle=\"like me, Hoping for a Nice Sunset -- Shogunzuka -- Kyoto, Japan -- Copyright 2009 Jeffrey Friedl, https:\/\/regex.info\/blog\/\"\/><\/a>\n<br\/><span class=\"camera-info robots-nocontent\">Nikon D700 + Nikkor 24-70mm f\/2.8 @ 62 mm &mdash; <sup>1<\/sup><big>\/<\/big>160 sec, <span class='f'>f<\/span>\/2.8, ISO 2000 &mdash;\n<a href=\"\/imageinfo.cgi?url=http%3A%2F%2Fregex.info%2Fi%2FJF7_010924.jpg\">map &amp; image data<\/a> &mdash; <a href=\"\/blog\/proximity\/i\/JF7_010924.jpg\">nearby photos<\/a><\/span>\n<br\/>like me,\n<br\/><span class='caption'>Hoping for <span class='nobr'>a Nice<\/span> Sunset<\/span>\n<\/div>\n\n<p>I find something oddly appealing about this shot. <span class='nobr'>I think<\/span> it's due to\nthe blurred background and almost complete lack of shadows, it makes it\nlook as if <span class='nobr'>I pasted<\/span> the guy into the empty scene from <span class='nobr'>a different<\/span> shot. <span class='nobr'>But I didn<\/span>'t do anything in post-processing. Nothing. <span class='nobr'>All the shots<\/span> on this\npage are rendered out of Lightroom with all default settings, except for\nshrinking to fit my blog, and for the sun-closeup shots, normalizing the\nwhite balance and then cropping.<\/p>\n\n\n\n<p><i><a href='\/blog\/2009-02-08\/1138'>Continued here...<\/a><\/i><\/p>\n\n","protected":false},"excerpt":{"rendered":"<p>Cameras are not nearly as good at capturing a wide range of brightnesses as our eyes, so a high contrast scene that appears fine to our eyes often ends up with either washed-out highlights or dark, muddy lowlights, like the two shots above.<\/p> <p>When using automatic exposure metering, most cameras default to trying to achieve a balance between the two extremes, often by sampling the scene across large areas of the frame. The simplest mode is for it to pick an exposure that averages the brightness levels seen throughout the frame, but this is apparently not very useful because it's [...]","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7,29],"tags":[],"_links":{"self":[{"href":"https:\/\/regex.info\/blog\/wp-json\/wp\/v2\/posts\/1137"}],"collection":[{"href":"https:\/\/regex.info\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/regex.info\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/regex.info\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/regex.info\/blog\/wp-json\/wp\/v2\/comments?post=1137"}],"version-history":[{"count":0,"href":"https:\/\/regex.info\/blog\/wp-json\/wp\/v2\/posts\/1137\/revisions"}],"wp:attachment":[{"href":"https:\/\/regex.info\/blog\/wp-json\/wp\/v2\/media?parent=1137"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/regex.info\/blog\/wp-json\/wp\/v2\/categories?post=1137"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/regex.info\/blog\/wp-json\/wp\/v2\/tags?post=1137"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}