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<blockquote data-quote="WayneF" data-source="post: 398698" data-attributes="member: 12496"><p>Sorry, clearly the technical term is not about ISO. <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" /></p><p></p><p>The very first sentence on the Wikipedia page you quoted from says:</p><p></p><p>In <a href="http://en.wikipedia.org/wiki/Photography" target="_blank">photography</a>, <strong>exposure value</strong> (<strong>EV</strong>) <strong>is a number that represents a combination of a <a href="http://en.wikipedia.org/wiki/Camera" target="_blank">camera</a>'s <a href="http://en.wikipedia.org/wiki/Shutter_speed" target="_blank">shutter speed</a> and <a href="http://en.wikipedia.org/wiki/F-number" target="_blank">f-number</a>, such that all combinations that yield the same <a href="http://en.wikipedia.org/wiki/Exposure_%28photography%29" target="_blank">exposure</a> have the same EV value </strong>(for any fixed scene <a href="http://en.wikipedia.org/wiki/Luminance" target="_blank">luminance</a>).</p><p></p><p>That seems clear.</p><p></p><p>Next top section, about FORMAL DEFINITION: EV = N squared/t. No ISO.</p><p></p><p>That seems clear.</p><p></p><p>If you take a light meter outdoors to meter the sun, it will meter EV 15 at ISO 100 (maybe f/16 1/125), and same sun will meter EV 18 at ISO 800 (maybe f/16 1/1000). EV is not about the ISO, and it is not about the light. It is about the shutter speed and f/stop numerical combination (which do change with ISO, if we imagine a proper exposure is involved). </p><p></p><p>f/16 1/125 is EV 15 in the huge chart on that same page.</p><p></p><p>f/16 1/1000 is EV 18 on the same huge chart.</p><p></p><p>Chart only involves shutter speed and f/stop, it does not mention ISO.</p><p></p><p>These two sun readings are NOT equivalent exposure values, but all shutter/aperture combinations on one EV row are Equivalent.</p><p>EV is the name of that equivalent row.</p><p></p><p>EV is about the camera settings, regardless of any ISO or light value, or even the lens cap.</p><p></p><p></p><p>Adding ISO to the EV concept does make that new combination be a light value then, but EV alone is not.</p></blockquote><p></p>
[QUOTE="WayneF, post: 398698, member: 12496"] Sorry, clearly the technical term is not about ISO. :) The very first sentence on the Wikipedia page you quoted from says: In [URL="http://en.wikipedia.org/wiki/Photography"]photography[/URL], [B]exposure value[/B] ([B]EV[/B]) [B]is a number that represents a combination of a [URL="http://en.wikipedia.org/wiki/Camera"]camera[/URL]'s [URL="http://en.wikipedia.org/wiki/Shutter_speed"]shutter speed[/URL] and [URL="http://en.wikipedia.org/wiki/F-number"]f-number[/URL], such that all combinations that yield the same [URL="http://en.wikipedia.org/wiki/Exposure_%28photography%29"]exposure[/URL] have the same EV value [/B](for any fixed scene [URL="http://en.wikipedia.org/wiki/Luminance"]luminance[/URL]). That seems clear. Next top section, about FORMAL DEFINITION: EV = N squared/t. No ISO. That seems clear. If you take a light meter outdoors to meter the sun, it will meter EV 15 at ISO 100 (maybe f/16 1/125), and same sun will meter EV 18 at ISO 800 (maybe f/16 1/1000). EV is not about the ISO, and it is not about the light. It is about the shutter speed and f/stop numerical combination (which do change with ISO, if we imagine a proper exposure is involved). f/16 1/125 is EV 15 in the huge chart on that same page. f/16 1/1000 is EV 18 on the same huge chart. Chart only involves shutter speed and f/stop, it does not mention ISO. These two sun readings are NOT equivalent exposure values, but all shutter/aperture combinations on one EV row are Equivalent. EV is the name of that equivalent row. EV is about the camera settings, regardless of any ISO or light value, or even the lens cap. Adding ISO to the EV concept does make that new combination be a light value then, but EV alone is not. [/QUOTE]
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