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Nikon DSLR Cameras
D800/D800E
Damn Auto-ISO and speedlight
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<blockquote data-quote="WayneF" data-source="post: 662826" data-attributes="member: 12496"><p>ISO 2200 is a half stop setting. The Auto ISO does frequently do 1/6 stops though, and 3/6 is a half. So the half stop is not any puzzle, but higher than 2 EV is the puzzle, at least as I originally stated it. There is a little more though.</p><p></p><p>The way that you can repeat that 2200-2500 result (intentionally cause it again) is to set either or both your flash compensations, the one in the camera menu, and/or the flash compensation set directly on the SB-800 body, either or both set to bit of positive flash compensation. If One of them is set to + 1/3 EV, then your ISO 400 Minimum might see ISO 2200. If both are set to + 1/3 EV, you might see the total of ISO 2500 (which is + 2/3 EV total compensation). They add.</p><p></p><p>Apparently this "only 2 EV above Minimum ISO with TTL flash" notion is Not limited by requests for additional flash compensation, which does seem reasonable. </p><p></p><p> A quick way to check if all things are actually as you believe them to be is to check the Info button (or top LCD) to notice the +/- compensation icon. This result will also show in the Rear LCD results (on screen that shows ISO settings). The icon will be on if any of the three comp sources (Exp comp, flash comp on camera, flash comp on flash) are not zero, and if that's a surprise, then we ought to find out which is on. They all add to the final exposure.</p><p></p><p>Surprising (to me), adding Exposure compensation (in contrast with Flash Compensation) does Not increase Auto ISO more than 2 EV above minimum, but it does cause additional TTL flash that performs the requested compensation. Because Exposure Comp does affect both ambient and flash exposure goals.</p><p>Adding additional Flash compensation can increase Auto ISO more than 2 EV above minimum. I'm puzzled how that could be explained rationally. <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 way it seems is that Auto ISO will Not expose the ambient reading more than the 2 EV (but then TTL will honor the Exposure Compensation anyway).</p><p></p><p>But as is the nature of flash, we do need to examine our result and decide if it needs retry with correction. <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" /></p></blockquote><p></p>
[QUOTE="WayneF, post: 662826, member: 12496"] ISO 2200 is a half stop setting. The Auto ISO does frequently do 1/6 stops though, and 3/6 is a half. So the half stop is not any puzzle, but higher than 2 EV is the puzzle, at least as I originally stated it. There is a little more though. The way that you can repeat that 2200-2500 result (intentionally cause it again) is to set either or both your flash compensations, the one in the camera menu, and/or the flash compensation set directly on the SB-800 body, either or both set to bit of positive flash compensation. If One of them is set to + 1/3 EV, then your ISO 400 Minimum might see ISO 2200. If both are set to + 1/3 EV, you might see the total of ISO 2500 (which is + 2/3 EV total compensation). They add. Apparently this "only 2 EV above Minimum ISO with TTL flash" notion is Not limited by requests for additional flash compensation, which does seem reasonable. A quick way to check if all things are actually as you believe them to be is to check the Info button (or top LCD) to notice the +/- compensation icon. This result will also show in the Rear LCD results (on screen that shows ISO settings). The icon will be on if any of the three comp sources (Exp comp, flash comp on camera, flash comp on flash) are not zero, and if that's a surprise, then we ought to find out which is on. They all add to the final exposure. Surprising (to me), adding Exposure compensation (in contrast with Flash Compensation) does Not increase Auto ISO more than 2 EV above minimum, but it does cause additional TTL flash that performs the requested compensation. Because Exposure Comp does affect both ambient and flash exposure goals. Adding additional Flash compensation can increase Auto ISO more than 2 EV above minimum. I'm puzzled how that could be explained rationally. :) The way it seems is that Auto ISO will Not expose the ambient reading more than the 2 EV (but then TTL will honor the Exposure Compensation anyway). But as is the nature of flash, we do need to examine our result and decide if it needs retry with correction. :) [/QUOTE]
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Nikon DSLR Cameras
D800/D800E
Damn Auto-ISO and speedlight
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