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Topic: why doesn't TTL metering take flash into consideration? (Read 6537 times)
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emanresu
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On my Rebel XSi the in-camera exposure meter does not seem to know about the built-in flash at all, so that even when I pop up the flash, it would still say some scenes are too dark. I found it a bit confusing to use whenever I use flash to shoot in a dark environment. Am I using it wrong? There is a function called flash exposure compensation, but the manual doesn't really explain it well. Maybe this is what I need to use? Thanks
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KeithB
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What mode are you in? Square, P, A...? Usually when I turn on the flash the shutter speed switches from 0.3 seconds (or whatever) to 1/60th or so. Here is a good explanation of canon flash modes: http://photonotes.org/articles/eos-flash/ |
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emanresu
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Thanks for the link, Keith. I haven't read it in detail yet but it does look containing a lot of good information.
I was in Manual mode when I had this question. I popped the flash and point it to the scene, and the exposure meter said it was too dark. However, when I took the picture, it came out okay, and if I had gone with the recommendation given by the meter, the picture would be way too bright. So does it mean that the meter didn't take the flash into consideration? (I will probably have a much better idea after I have read the link...)
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KeithB
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The meter never takes flash into consideration, it is not a flash meter! I don't know what happens in manual mode. After all, it is "manual mode", you are supposed to be in control of everything.
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Bob Atkins
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Well, the meter can take flash into consideration if you use FEL (flash exposure lock), and the meter does actually read the pre-flash signal put out by the speedlite to calculate flash exposure.
However what you were seeing is the background exposure. In manual mode you get what you dial in of course. In AV mode there's a custom function which allows exposure to either take the background light level into account and expose properly for it, using the flash for the main subject illumination (low sync), or you can chose to have exposure set only for the flash illumination and let the background go dark.
If you read the manual you'll find the description on page 74 might help.
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emanresu
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Thanks Keith and Bob! I will read the manual when I get home. FAQ#7 from the link Keith posted also answers this question.
I have read the manual at least 3 times already, but quite frankly, some of these advanced features didn't register with me. Funny story - the other day, my AEB range seemed to be possessed because it went from -1 to +3 instead of the normal -2 to +2. I flipped through almost every page of the manual but didn't find any answer. Finally I realized that it was because I jacked up the exposure compensation to +1.
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