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emes Jan 28, 2008 6:46 PM

Auto ISO is not working with slow sync flash.
I set auto ISO on, with max of 400. With or without flash in dim condition ISO goes to 400. I change flash to slow sync flash and ISO stays fixed on 100. Is it normal or I set something wrong?

Nagasaki Jan 29, 2008 6:33 AM

Sounds about right. With slow sync you want a long exposure for the background ambient light exposure. Since you've opted for a long exposure why increase the ISO to reduce the exposure time?

emes Jan 29, 2008 10:03 AM

Slow sync allowes to capture background. "slow" means slower than sync for flash. With ISO 100 background was blured, but with ISO 400 wasnt. Actually I have been shooting pics without flash and ISO 400 was fine, I tried some pics with flash on and was fine as well. Finally I tried slow sync flash and was surprised why ISO is reduced and shooter speed was slowed and pic is done blured.

Nagasaki Jan 29, 2008 5:45 PM

Your camera is working the way I'd expect it to. I experimented with my D80 and found that the ISO is not increased when I turn on the flash regardless of the flash setting. What does change is the shutter speed and it's a lot slower with slow flash selected but that's to be expected as it's exposing for the ambient light. It could be that you've specified a higher value for the minimum shutter speed which is why the ISO is increased when you don't set the camera to slow.

As for the bluring I'd use a tripod in the sort of situtation you describe or manually up the ISO. At least you now know how the camera operates and can select the settings that best achieve what you intend.


emes Jan 29, 2008 7:02 PM

Thanks for help, I have expected same auto ISo mechanism, but everything is ok , now I will have it on my mind.

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