{"id":1088,"date":"2009-05-28T03:47:04","date_gmt":"2009-05-28T07:47:04","guid":{"rendered":"http:\/\/www.planetneil.com\/tangents\/?p=1088"},"modified":"2020-06-13T19:22:44","modified_gmt":"2020-06-13T23:22:44","slug":"shutter-speed-controls-background-exposure","status":"publish","type":"post","link":"https:\/\/neilvn.com\/tangents\/shutter-speed-controls-background-exposure\/","title":{"rendered":"Shutter speed controls background exposure?"},"content":{"rendered":"<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone\" src=\"https:\/\/neilvn.com\/tangents\/images\/flash\/Danielle-219.jpg\" alt=\"\" width=\"500\" height=\"750\" \/><\/p>\n<h1>Shutter speed controls background exposure?\u00a0Usually &#8230;<\/h1>\n<p>Something\u00a0I kick against when I try to teach others about flash photography, is the use of short-cut phrases. Those axioms\u00a0that are supposed to help the\u00a0understanding of how to mix flash with ambient light, can often mislead you since\u00a0they don&#8217;t give you all the information.<\/p>\n<p><a href=\"https:\/\/neilvn.com\/tangents\/flash-exposure-is-controlled-by-aperture-for-manual-flash\/\">Two of those phrases were recently discussed here:<\/a><\/p>\n<ul>\n<li>aperture controls flash exposure,<\/li>\n<li>shutter speed controls available light.<\/li>\n<\/ul>\n<p>These are merely <strong>reductions<\/strong> of the way that shutter speed, aperture and ISO inter-relate with available light and flash. With those simplifications,\u00a0those two phrases then become misleading.\u00a0 On top of that, they become meaningless when you work with <a href=\"https:\/\/neilvn.com\/tangents\/when-aperture-does-not-control-flash-exposure\/\">TTL flash<\/a>.<\/p>\n<p>Instead, I would really urge anyone who wants to come to grips with understanding how flash and available light correlate via your camera settings, to try and get the wider view on all of this, and <a href=\"https:\/\/neilvn.com\/tangents\/manual-flash-ttl-flash\/\">understand how manual flash and TTL flash differ<\/a>.<\/p>\n<p>I encountered another one of those misleading phrases recently while teaching someone. When I showed a sequence of images as part of the explanation of balancing manual flash with available light, the reply was &#8230; &#8220;<em>shutter speed controls the background exposure&#8221;<\/em>.\u00a0 Except,\u00a0in this case, the automatic response\u00a0was the\u00a0wrong answer.<\/p>\n<p>So let&#8217;s look at the photo above, which is the photo in question:<br \/>\nMy settings\u00a0were:\u00a0\u00a01\/40th @ f2.8 @ 400 ISO<\/p>\n<p>The setup was as follows ..<\/p>\n<p><!--more--><\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>On this wedding day, it was raining hard outside, so I had to come up with all kinds of ideas for interesting portraits indoors in this house.\u00a0 Outside the main bedroom on the first floor, was the landing of the steps leading up from the living room.\u00a0 There was a blue mural with dolphins painted on it, and you can see this as the out-of-focus blue area in this photo.<\/p>\n<p>Inside the bedroom where three large incandescent lamps.\u00a0 (Tungsten light).<\/p>\n<p>To light the blue mural, I placed a flashgun on a light-stand on the ground floor.\u00a0 The flashgun (a Q-flash) was set to 1\/8th power (or there-abouts).\u00a0 It was set to manual output, and the flashgun was pointed straight up into the stairwell leading to the bedrooms.<\/p>\n<p>So looking at this photo, the blue background (the mural), is lit entirely by manual flash.\u00a0 The bride in the foreground is lit mostly by the incandescent lamps inside the bedroom.<\/p>\n<p>So let&#8217;s break this down into two parts .. the <strong>flash exposure<\/strong> and the <strong>ambient exposure.<\/strong><\/p>\n<p><strong>Manual flash exposure<\/strong>\u00a0is controlled by 4 settings:<br \/>\n&#8211; aperture,<br \/>\n&#8211; ISO,<br \/>\n&#8211; distance between subject and light source,<br \/>\n&#8211; power setting on the flashgun \/ power-pack.<\/p>\n<p>In this specific scenario, the distance is a fixed value, since the light-stand can&#8217;t really be moved from its position.\u00a0 Similarly, the power setting of the flashgun is fixed, since I can&#8217;t run like a lunatic up and down the stairs to adjust the power.\u00a0 That would just destroy my cool professional demeanor that I was trying to maintain in front of my client\u00a0.. while actually sweating trying to come up with fresh ideas.<\/p>\n<p>Okay, so distance is fixed, and power is fixed.\u00a0 That leaves aperture and ISO as my two controls that I have available to me to control how bright the blue background will appear.<\/p>\n<p>In other words, from where I stand inside the bedroom, I can control whether the blue background will be washed out (over-exposed to an extent), or saturated (under-exposed to an extent) &#8230; simply by dialing my aperture and ISO.<\/p>\n<p>In this case I liked how it appeared with my aperture at f2.8 and my ISO at 400.<\/p>\n<p>&nbsp;<\/p>\n<h2>Next up, let&#8217;s consider the available light<\/h2>\n<p>Available light is controlled by aperture, ISO and shutter speed. Always has been, and probably always will be.<\/p>\n<p>In this scenario, our aperture and ISO is fixed for my particular liking of how the blue appears in the image as I saw it on the back of my LCD screen.\u00a0 This leaves <strong>shutter speed<\/strong> as my only <strong>independent<\/strong>\u00a0control for available light.<\/p>\n<p>And now with my shutter speed, I can control how bright my subject (which is lit only with ambient light), appears in relation to the background (which is lit by flash).<\/p>\n<p>&nbsp;<\/p>\n<h2>Bringing it all together<\/h2>\n<p>So for <em>this<\/em> particular example, the usual idiom that we hear that shutter speed controls the <strong>background exposure<\/strong>, is thrown upside down. For this specific\u00a0scenario, shutter speed was the independent control for my <strong>foreground exposure<\/strong>.<\/p>\n<p>Note that I didn&#8217;t say that &#8220;shutter speed now controls the foreground exposure&#8221;.\u00a0 That would be an incomplete description, since aperture and ISO <strong>also<\/strong> control the ambient exposure for my subject in the foreground. It is simpler however with <strong>manual flash<\/strong>, to change the shutter speed as the <strong>independent<\/strong> control for available light.\u00a0 And note, I mention manual flash specifically.\u00a0 <a href=\"https:\/\/neilvn.com\/tangents\/manual-flash-ttl-flash\/\">TTL flash<\/a> is an entirely different beast.<\/p>\n<p>So here is how I controlled my foreground exposure in this scenario. I changed my shutter speed from 1\/40th to 1\/100th, and the bride was near-silhouetted against the background. There is a change in the exact colour of the blue background, because I played with the WB of the raw image, so don&#8217;t let that mislead you. And yes, I know there is some subject movement\u00a0in that shot. But the image works. ; )<\/p>\n<p>&nbsp;<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone\" src=\"https:\/\/neilvn.com\/tangents\/images\/flash\/Danielle-220.jpg\" alt=\"\" width=\"500\" height=\"750\" \/><\/p>\n<p>&nbsp;<\/p>\n<h2>Summary<\/h2>\n<p>A clear understanding of how shutter speed, aperture and ISO inter-relate for ambient light and manual\u00a0flash and TTL flash, is far more useful than learning shortcut phrases. When you&#8217;re in an unusual situation, you&#8217;ll be better of with real knowledge, rather\u00a0than\u00a0memorized phrases that don&#8217;t give you the entire story.<\/p>\n<p>&nbsp;<\/p>\n<h2>Related articles<\/h2>\n<ul>\n<li><a href=\"https:\/\/neilvn.com\/tangents\/photography-tutorial-balancing-flash-and-ambient-exposure\/\">Balancing flash and ambient exposure<\/a>\u00a0 (model: Anelisa)<\/li>\n<li><a href=\"https:\/\/neilvn.com\/tangents\/when-aperture-does-not-control-flash-exposure\/\">When aperture does NOT control flash exposure<\/a><\/li>\n<li><a href=\"https:\/\/neilvn.com\/tangents\/flash-exposure-is-controlled-by-aperture-for-manual-flash\/\">Flash exposure is controlled by aperture \u2013 but only for manual flash<\/a><\/li>\n<li><a href=\"https:\/\/neilvn.com\/tangents\/flash-photography-tutorial\/\">Tutorial \u2013 balancing flash and ambient<\/a>\u00a0 (model:\u00a0Camille)<\/li>\n<li>Tutorials:\u00a0<a href=\"https:\/\/neilvn.com\/tangents\/flash-photography-techniques\/\">Flash Photography Techniques<\/a><\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Shutter speed controls background exposure?\u00a0Usually &#8230; Something\u00a0I kick against when I try to teach others about flash photography, is the use of short-cut phrases. Those axioms\u00a0that are supposed to help the\u00a0understanding of how to mix flash with ambient light, can often mislead you since\u00a0they don&#8217;t give you all the information. Two of those phrases were&nbsp;<a class=\"more-link\" href=\"https:\/\/neilvn.com\/tangents\/shutter-speed-controls-background-exposure\/\" rel=\"nofollow\">Read more inside&#8230;<\/a><\/p>\n","protected":false},"author":1,"featured_media":30418,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[15,22,42],"tags":[56],"yst_prominent_words":[3364,9799,1393,9809,9804,1421,9806,9807,9796,1417,8126,8048,1198,1215,9714,9792,1216,9789,9801,9795],"class_list":{"0":"post-1088","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-flash-photography","8":"category-lighting","9":"category-technique","10":"tag-flash-photography-tips","11":"entry"},"_links":{"self":[{"href":"https:\/\/neilvn.com\/tangents\/wp-json\/wp\/v2\/posts\/1088"}],"collection":[{"href":"https:\/\/neilvn.com\/tangents\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/neilvn.com\/tangents\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/neilvn.com\/tangents\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/neilvn.com\/tangents\/wp-json\/wp\/v2\/comments?post=1088"}],"version-history":[{"count":7,"href":"https:\/\/neilvn.com\/tangents\/wp-json\/wp\/v2\/posts\/1088\/revisions"}],"predecessor-version":[{"id":49015,"href":"https:\/\/neilvn.com\/tangents\/wp-json\/wp\/v2\/posts\/1088\/revisions\/49015"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/neilvn.com\/tangents\/wp-json\/wp\/v2\/media\/30418"}],"wp:attachment":[{"href":"https:\/\/neilvn.com\/tangents\/wp-json\/wp\/v2\/media?parent=1088"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/neilvn.com\/tangents\/wp-json\/wp\/v2\/categories?post=1088"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/neilvn.com\/tangents\/wp-json\/wp\/v2\/tags?post=1088"},{"taxonomy":"yst_prominent_words","embeddable":true,"href":"https:\/\/neilvn.com\/tangents\/wp-json\/wp\/v2\/yst_prominent_words?post=1088"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}