How do i edit this

Started Jan 28, 2014 | Discussions thread
Victor Engel Forum Pro • Posts: 18,151
Re: How do i edit this

Dareshooter wrote:

The only possibility is to stop down AND increase ISO. This cuts down the ambient light, thus reducing the power requirement of the flash (does not increase the power of the flash). That would work, but it requires a smaller aperture.

Yes the aperture for would have to be stopped down to achieve the sync speed but the higher ISO of 400 would mean that the GN would increase from 13 to around 26 providing enough power for fill light.

Guide number is not a unit of power. There is no more power when the guide number is increased by increasing the ISO. The guide number increases because less power is needed at a higher ISO because less light is needed for a proper exposure since the signal is amplified by the higher ISO setting. The signal is amplified at the sensor reading step, not at the flash production step.

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Victor Engel

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