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A poll about Auto ISO action with hot shoe TTL flash
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<blockquote data-quote="WayneF" data-source="post: 536256" data-attributes="member: 12496"><p>Thanks Walt. I do think both the D7100 and D5300 are indicating as being in the recent group C (since 2012), with 4x Minimum ISO as a limit with TTL flash. </p><p></p><p>But you have pointed out that there is a little mystery, for two new reasons actually, and this would be my fault, because I failed to specify the problem well enough. You did your job, but I think my part may be a bit shabby. But in my defense, certainly the fact that the flash did not use ISO 3200 like group B does seems like stand alone evidence of Group C.</p><p> </p><p>To me, your D5300 situation does not cause attention, it sounds just like it ought to be, as expected, in a normal routine situation.</p><p></p><p></p><p></p><p>I am a little afraid to ask, but I did not understand that part about the D7100. What was the Minimum ISO before? Hopefully ISO 500? (4x500 = 2000).</p><p></p><p></p><p>The D7100 only going to ISO 250 would mean TTL did not need more (like if at a close distance) if it didn't need to. Do you remember an approximate distance then? Without the flash, it needed ISO 3200, so the room was properly dim, but if the TTL flash was pretty close to subject, then it may only need ISO 250 at f/4.5. Which was surely right, and I can duplicate that situation here if at a close distance. That is Effect #1 we discovered. It uses only enough ISO that the TTL flash actually needs, less than 4x Minimum. I had seen that before, but did not stop to think (it is sort of wondrous actually). But that does not show that ISO 400 is a limit. </p><p></p><p>And so as yet, I don't know what a clear specific complete test situation would be. (arguing with myself here, sane readers could stop here <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" /> ). I think that it did not use ISO 3200 with flash is pretty strong evidence of Group C, but close range could override. However, it does seem clear that if we said camera A mode and say f/22 to be impossible, then any normal distance would need more than ISO 400, so then it would be meaningful if it stopped at a ISO 400 limit (and the picture would be dark too). But it doesn't happen that way.</p><p></p><p>I've had my D800 nearly 4 years, and I know it does limit at ISO 400 with TTL flash, and in any normal situation, it certainly does, ISO 400 is all I ever see if Auto ISO is used. But just playing with it now with f/22 at 20 feet in a dark room, which would be impossible for the flash power and ISO 400 (and the picture would be dark at ISO 400), I see that the ISO will go even higher with TTL flash, to ISO 1000 in my test (20 feet at f/22), to deliver a halfway reasonable picture anyway (power was still insufficient). That is Effect #2 that we just discovered. The viewfinder shows ISO 400 then, but the data shows it used ISO 1000. The old group A did that too, and I didn't realize they still did that. I suppose #1 and #2 are actually the same thing in different situations.</p><p></p><p>So IMO, it sounds like it should still be worded that Group C cameras do stop Auto ISO at ISO 400 if with a TTL flash. But if does not need ISO 400, it may stop sooner, your 250, and I saw it too, by playing with a close distance. And there is a detail or two, but stopping at ISO 400 still leaves a wide range of TTL flash power to handle different situations. But also, when the situation does need more that ISO 400 can provide (meaning the flash power level capacity was insufficient for ISO 400), then it will use whatever ISO it needs, like ISO 1000. </p><p></p><p>So you just caused a need for a rewrite about Group C. <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>I'm not sure what a complete test situation should be, but it still seems fair to say that in most normal routine situations, Group C does stop advancing at ISO 400. Certainly it does not still go to ISO 3200 like Group B did. But there are additional ifs and buts about it too. <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: 536256, member: 12496"] Thanks Walt. I do think both the D7100 and D5300 are indicating as being in the recent group C (since 2012), with 4x Minimum ISO as a limit with TTL flash. But you have pointed out that there is a little mystery, for two new reasons actually, and this would be my fault, because I failed to specify the problem well enough. You did your job, but I think my part may be a bit shabby. But in my defense, certainly the fact that the flash did not use ISO 3200 like group B does seems like stand alone evidence of Group C. To me, your D5300 situation does not cause attention, it sounds just like it ought to be, as expected, in a normal routine situation. I am a little afraid to ask, but I did not understand that part about the D7100. What was the Minimum ISO before? Hopefully ISO 500? (4x500 = 2000). The D7100 only going to ISO 250 would mean TTL did not need more (like if at a close distance) if it didn't need to. Do you remember an approximate distance then? Without the flash, it needed ISO 3200, so the room was properly dim, but if the TTL flash was pretty close to subject, then it may only need ISO 250 at f/4.5. Which was surely right, and I can duplicate that situation here if at a close distance. That is Effect #1 we discovered. It uses only enough ISO that the TTL flash actually needs, less than 4x Minimum. I had seen that before, but did not stop to think (it is sort of wondrous actually). But that does not show that ISO 400 is a limit. And so as yet, I don't know what a clear specific complete test situation would be. (arguing with myself here, sane readers could stop here :) ). I think that it did not use ISO 3200 with flash is pretty strong evidence of Group C, but close range could override. However, it does seem clear that if we said camera A mode and say f/22 to be impossible, then any normal distance would need more than ISO 400, so then it would be meaningful if it stopped at a ISO 400 limit (and the picture would be dark too). But it doesn't happen that way. I've had my D800 nearly 4 years, and I know it does limit at ISO 400 with TTL flash, and in any normal situation, it certainly does, ISO 400 is all I ever see if Auto ISO is used. But just playing with it now with f/22 at 20 feet in a dark room, which would be impossible for the flash power and ISO 400 (and the picture would be dark at ISO 400), I see that the ISO will go even higher with TTL flash, to ISO 1000 in my test (20 feet at f/22), to deliver a halfway reasonable picture anyway (power was still insufficient). That is Effect #2 that we just discovered. The viewfinder shows ISO 400 then, but the data shows it used ISO 1000. The old group A did that too, and I didn't realize they still did that. I suppose #1 and #2 are actually the same thing in different situations. So IMO, it sounds like it should still be worded that Group C cameras do stop Auto ISO at ISO 400 if with a TTL flash. But if does not need ISO 400, it may stop sooner, your 250, and I saw it too, by playing with a close distance. And there is a detail or two, but stopping at ISO 400 still leaves a wide range of TTL flash power to handle different situations. But also, when the situation does need more that ISO 400 can provide (meaning the flash power level capacity was insufficient for ISO 400), then it will use whatever ISO it needs, like ISO 1000. So you just caused a need for a rewrite about Group C. :) I'm not sure what a complete test situation should be, but it still seems fair to say that in most normal routine situations, Group C does stop advancing at ISO 400. Certainly it does not still go to ISO 3200 like Group B did. But there are additional ifs and buts about it too. :) [/QUOTE]
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