(1dx) Best way to use flash in Av mode?

Started Aug 18, 2013 | Discussions thread
rbarta
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Re: (1dx) Best way to use flash in Av mode?
In reply to keithop, Aug 19, 2013

keithop wrote:

Hi

Apologies if this is a simple (atupid) question but it's confusing me at the moment.

1DX on Av mode. Aperture set to 1.4, fine, 580exII in ettl mode.

Just experimenting indoors to get familiar with the flash system and with the flash direct, all I get are hopelessly over exposed images.

I'd simply have expected the camera to work the shutter speed, iso and flash output to get the exposure reasonably ok but it seems to put the iso at 400, shutter speed not particularly fast (sometimes 1/25) and over expose :/

I've reset all camera settings to make sure I'm not doing something silly so I must be missing something ?

Thanks for any ideas

RTM.

Actually you have 2 problems.

p.125 You have Auto-ISO set. With Flash it goes to 400 (unless that will cause overexposure, then it will be set lower). BTW, it sets it to this because it will prob be able to pick up some background and won't use tons of flash energy, it is a general setting for people who are not in manual.

I highly suggest you don't use Av for flash as it will set exposure to normal and use flash for fill only. This is why the overexposure is happening.  It sets exposure to normal because you are making the depth of field as the #1 priority.

Time to step up to Manual mode and set your ISO manually too. With a flash you actually are dealing with 2 exposures, one for the scene and one for what the flash is illuminating. This might help http://www.youtube.com/watch?v=vEnAhkL0i38

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