Question about Canon EOS 40D Digital Camera

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Flash exposure does not work in Av and Tv mode

My EOS40D does not seem to account for the flash when calculating exposure in Av and Tv mode. In program mode, the flash works fine, but when I enter for example aperture priority and set the aperture to F4.0 or F5.6 and turn the flash on, I still get exposure times like 1/15 indoor. The flash fire anyway, and it is even used when I press the button down do meter the exposure, but the shutter speed is not set correct. In shutter speed priority I get the same problem. If I set shutter speed to 1/60, the aperture flashes to indicate under-exposure.
In short, it seem to calculate exposure as if the flash should not fire. It does however fire...
I have checked my settings over and over and cannot find anything but standard settings, and yes, the flash is activated.

Any idea what is wrong?

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  • ottopaul Sep 11, 2008

    Thanks! I have begun to realize that it is supposed to work this way.

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There is nothing wrong here - the camera computes the exposure as the flash is not firing. The flash will fire and it will adapt the power to the received light. You must go into M ot AV, fix your parameters and shoot. The flash will adapt to your whishes - only take care to not choose a shooting time to small (1/200 or 1/60 - you have settings for it).

This is not a bug, but a feature.

Posted on Sep 11, 2008

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