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Favor to ask of owners with SB-700 or SB-910
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<blockquote data-quote="WayneF" data-source="post: 413324" data-attributes="member: 12496"><p>Any method will take the picture, but yes, the test has to use the cord, with camera closer than the TTL BL direct flash, for the test to be meaningful.</p><p></p><p>The system knows that the commander remote flashes are off camera, so are at an unknown different distance than the camera.</p><p></p><p>The hot shoe cord is on the camera, so to speak, no difference in the hot shoe itself. No way to know the cord is even being used. It is just a hot shoe extension cord.</p><p></p><p>The idea is that direct flash pictures are often overexposed, due to metering being affected by the dark background behind the direct subject. Black or dark subjects increase exposure. So the metering might be trying to light the dark background, when that is not the pictures goal about subject.</p><p></p><p>So TTL BL (direct flash) assumes a hot shoe flash on camera, and uses the D lens distance to compute a guide number, and if the metered TTL BL exposure seems too much for the guide number distance (due to dark background, etc), it backs the flash down, to agree with the safe guide number that it knows for the D lens distance. Good in theory, for a hot shoe flash (except zoom D lens distances are rather inaccurate, and can cause similar problems as in the test). </p><p></p><p> But in practice, if the flash is not at the same distance as the camera (specifically if the camera is closer than the flash), then it doesn't know where the flash is, doesn't even know there is an issue, and it may back off flash power when it should not. We can get severely underexposed pictures (the test case).</p><p></p><p>Switching to TTL (instead of TTL BL) overrides, and it forgets about D lens distance, and just takes the picture metered.</p><p>Spot metering forces TTL mode.</p><p>Also tilting the flash head tells it that is not direct flash, so again it forgets about D lens distance.</p><p></p><p>Or the Commander expects off camera flashes, and it forgets D lens distance too.</p><p></p><p>I see that the third party flashes (Yongnuo, etc) do not have the head tilt switch, and they also cause the metering to forget the D-lens distance, and we get good results in this test case. So which is a good thing when camera is closer than the flash. I was just wondering if the latest Nikons might have changed too? I suspect not, but don't know.</p></blockquote><p></p>
[QUOTE="WayneF, post: 413324, member: 12496"] Any method will take the picture, but yes, the test has to use the cord, with camera closer than the TTL BL direct flash, for the test to be meaningful. The system knows that the commander remote flashes are off camera, so are at an unknown different distance than the camera. The hot shoe cord is on the camera, so to speak, no difference in the hot shoe itself. No way to know the cord is even being used. It is just a hot shoe extension cord. The idea is that direct flash pictures are often overexposed, due to metering being affected by the dark background behind the direct subject. Black or dark subjects increase exposure. So the metering might be trying to light the dark background, when that is not the pictures goal about subject. So TTL BL (direct flash) assumes a hot shoe flash on camera, and uses the D lens distance to compute a guide number, and if the metered TTL BL exposure seems too much for the guide number distance (due to dark background, etc), it backs the flash down, to agree with the safe guide number that it knows for the D lens distance. Good in theory, for a hot shoe flash (except zoom D lens distances are rather inaccurate, and can cause similar problems as in the test). But in practice, if the flash is not at the same distance as the camera (specifically if the camera is closer than the flash), then it doesn't know where the flash is, doesn't even know there is an issue, and it may back off flash power when it should not. We can get severely underexposed pictures (the test case). Switching to TTL (instead of TTL BL) overrides, and it forgets about D lens distance, and just takes the picture metered. Spot metering forces TTL mode. Also tilting the flash head tells it that is not direct flash, so again it forgets about D lens distance. Or the Commander expects off camera flashes, and it forgets D lens distance too. I see that the third party flashes (Yongnuo, etc) do not have the head tilt switch, and they also cause the metering to forget the D-lens distance, and we get good results in this test case. So which is a good thing when camera is closer than the flash. I was just wondering if the latest Nikons might have changed too? I suspect not, but don't know. [/QUOTE]
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