Having a blond moment - flash power

[cymruchris]

Where I am it's late - and I'm pretty sure I'm right (aren't we always?) - but would like a confirmation on a thought.

I'm going somewhere tomorrow where I will be using two x 580EX2 flashguns - If set to manual - and say at 1/64 power on both units - if they were next to each other pointing in the same direction - would that be the equivalent of 1/32 power from a single head? (Roughly)

Are my brains working? Or am I missing the obvious?

Please put my mind at rest

(I'm using the flashes in sealed bags - so thinking I might put both in one bag at a lower power, rather than use one at a time at a higher power - then fire them both off at a lower intensity so that the batteries last longer, and I don't have to open the bag so often..... )

 

[Terrywoodenpic]

Two manual flashes at the same power = twice the output= + one stop of power.

But it is hard to tell about the power usage factor.

 

[cymruchris]

Two manual flashes at the same power = twice the output= + one stop of power.

But it is hard to tell about the power usage factor.

Good point - the batteries may not last twice as long by firing off at half the power...

 

[HoppyUK]

Where I am it's late - and I'm pretty sure I'm right (aren't we always?) - but would like a confirmation on a thought.

I'm going somewhere tomorrow where I will be using two x 580EX2 flashguns - If set to manual - and say at 1/64 power on both units - if they were next to each other pointing in the same direction - would that be the equivalent of 1/32 power from a single head? (Roughly)

Are my brains working? Or am I missing the obvious?

Please put my mind at rest

(I'm using the flashes in sealed bags - so thinking I might put both in one bag at a lower power, rather than use one at a time at a higher power - then fire them both off at a lower intensity so that the batteries last longer, and I don't have to open the bag so often..... )

Yes.

Good point - the batteries may not last twice as long by firing off at half the power...

Maybe not exactly twice as long, but there or thereabouts. Very broadly these things work pro-rata, so when you halve the power you'll get twice as many flashes, recycle time will be twice as fast, and the flash duration will be about half, too.