5d mk3 overiding auto iso setting at 400 with flash

Has anyone found a way to stop the 5D mk3 from defaulting to ISO400 when in Auto ISO mode and you use a flash.
It is a total pain when in Av mode using flash indoors. The flashgun starts using all it's power and the shutter speed slows to camera shack levels.

sounds like getting out of autoiso mode would be the quickest fix for this

I'm trying to figure out why you would want auto ISO, auto Flash, and AV mode all at once. Surely you want to exhibit some control over some elements of your image.

gonzogolf wrote in post #16066410
I'm trying to figure out why you would want auto ISO, auto Flash, and AV mode all at once. Surely you want to exhibit some control over some elements of your image.

Once you learn how the evaluative meter works- it is idiosyncratic- you can get great consistency.
So why not use Av- Canon have invested huge money( I expect) in trying to get their metering system to be a reasonable judge of scene and lighting. So in normal lighting when you just want to record the scene with fewer, less deep shadows- let the camera do the thinking- especially in a fast flowing event scenario.
If you have a moment to change from backlit to top lit to unlit where the action is - manual adjustments are not fast enough- you've missed the shot.
That's why even cameras like 1D range have P,Av, & Tv- because you sometimes/often need it.

john5189 wrote in post #16066446
Once you learn how the evaluative meter works- it is idiosyncratic- you can get great consistency.
So why not use Av- Canon have invested huge money( I expect) in trying to get their metering system to be a reasonable judge of scene and lighting. So in normal lighting when you just want to record the scene with fewer, less deep shadows- let the camera do the thinking- especially in a fast flowing event scenario.
If you have a moment to change from backlit to top lit to unlit where the action is - manual adjustments are not fast enough- you've missed the shot.
That's why even cameras like 1D range have P,Av, & Tv- because you sometimes/often need it.

I think Gonzogolf was just saying why auto ISO and Av. You already have the auto adjustments that you want with the AV, so just set the ISO that you want to use.

I don't see the problem here. The camera isn't setting the ISO you want it to, so just set it yourself.

sandpiper wrote in post #16066524
I think Gonzogolf was just saying why auto ISO and Av. You already have the auto adjustments that you want with the AV, so just set the ISO that you want to use.

I don't see the problem here. The camera isn't setting the ISO you want it to, so just set it yourself.

Exactly. Too many moving targets for my taste.

gonzogolf wrote in post #16066528
Exactly. Too many moving targets for my taste.

With the 5D mk3 you can set a minimum shutter speed in Av when in auto ISO- so the camera raises the ISO in stead of slowing the shutter speed to camera shake levels. Very useful in a dynamic situation.

The flash restricts the ISO range to 100-400, instead of 100-12800(my set limit) without flash.

Once the camera has assessed the EV range to target- everything else is just a simple lookup chart of aperture, shutter speed and ISO- with EComp adjustment- just the same number of variable the camera always has to use.

So I dont know my shutter speed, but a range, I dont know my ISO, but a range, And then I add the delightfully quirky nature of ETTL. My point stands.

gonzogolf wrote in post #16066590
So I dont know my shutter speed, but a range, I dont know my ISO, but a range, And then I add the delightfully quirky nature of ETTL. My point stands.

You may not know, but the camera does or at least a close approximation.

As for ETTL-II once you have learnt how to use it it is quite predictable.

But it would be useful if you could supply info in regard to OP question.

That's already given. Set the ISO manually. That's the only way. Some cameras default to ISO 1600 if you bounce the flash and use P mode, but that's not what the OP wanted.
I also agree that in most cases, M mode is easier to work with than Av, when using a flash as well.

Yeah, I much prefer to set my ISO manually.

I generally also know how much ambient I want to have present, so I set my shutter speed. I also set my aperture based on the DoF that I want.

... which means I shoot with the camera in manual mode and make all those adjustments myself and let ETTL take care of the flash.

That said, there are times that I shoot with the camera in Av too (e.g. events), but I still choose an ISO setting manually.

Yes but auto ISO is brilliant when you can set a minimum shutter speed when in Av- I agree AutoISO is useless in any other mode because you are giving away too much control.

If I set
Av mode- aperture f/4, min shutter speed should never go below 1/125th second
The camera will always set the ISO to the lowest possible setting according to these above settings and the light reading from the built in metering system. Hence minimising noise.

But when you are indoors with reasonable light levels that say ISO8000 would be selected and you want to use fill-in flash, you have to manually set the ISO because the camera wont Auto ISO with flash on, which is odd that it doesn't and a shame too.

So Canon have restricted the performance envelope of the 5D mk3 for no discernible reason, which is irritating.

how could the camera possibly know what ISO you want to use?

john5189 wrote in post #16067262
Yes but auto ISO is brilliant when you can set a minimum shutter speed when in Av- I agree AutoISO is useless in any other mode because you are giving away too much control.

If I set
Av mode- aperture f/4, min shutter speed should never go below 1/125th second
The camera will always set the ISO to the lowest possible setting according to these above settings and the light reading from the built in metering system. Hence minimising noise.

But when you are indoors with reasonable light levels that say ISO8000 would be selected and you want to use fill-in flash, you have to manually set the ISO because the camera wont Auto ISO with flash on, which is odd that it doesn't and a shame too.

So Canon have restricted the performance envelope of the 5D mk3 for no discernible reason, which is irritating.

John, I'm in agreement with you on this. Is there any practical reason that we can't get higher ISOs with a flash mounted? Granted, 400 is a good compromise.