5DIII + 580EX II = Under exposed

Started Jun 18, 2012 | Discussions thread
qianp2k Forum Pro • Posts: 10,350
Re: 5DIII + 580EX II = Under exposed

guy schlacter wrote:

Regarding Phil's comment:

However all your compositions are right in Canon's sweet spots. It's a long thread but my recollection of the early examples were full flash illumination not fill.

IF you look at the image info on that first car show image (ISO 400 1/200 f2.8), I would esitimate it at 2-4 stops below ambient (estimated ambient ISO 1600-6400 1/200 f2.8 in television quality - avg auditorium)

I believe the fix is related to the mode that you have the camera in.

You will always get some blend of fill flash using Av and Tv mode as the settings (ss/ aperture/ IOS) will be set for ambient, and flash will simply brighten the subject. the relationship will be relative to the shutter drag / EC setting.

Flash becomes the primary light when in P and M modes as far as I can tell.

That is what by default or on what we have been told.  But actually regardless under what mode ETTL checks ambient light and your camera metering (aperture, shutter and ISO), it will still use ambient light as much as possible, and use flash when ambient light is not enough.  In another words, even under Av/Tv mode, when ETTL sees there is not enough ambient light such as in evening or indoor, it will emit necessary flash power to make sure your subject will be exposed correctly.

Let us know what you sort out.


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