580exII and 430ex same power?

[sinitry23]

Let say I set both flash to the same settings.

1/4 power, 70mm, same distance and fresh batteries. Does both flash output the same amount of light or does the 580 output more?

[René Damkot]

580 puts out about a stop more.
1/1 is GN 43 on a 430EX, and GN 58 on a 580EX.
(in meters, ISO 100, 105mm zoom, IIRC ;))

[msowsun]

Let say I set both flash to the same settings.

1/4 power, 70mm, same distance and fresh batteries. Does both flash output the same amount of light or does the 580 output more?

At a 70mm setting the GN for the 430 drops from 43 to 37 and the 580 drops from 58 to 46.

With both at 1/4 power, there may not be much of a difference.

http://www.kjsl.com/~dave/speedlites.html

[PacAce]

At a 70mm setting the GN for the 430 drops from 43 to 37 and the 580 drops from 58 to 46.

With both at 1/4 power, there may not be much of a difference.

http://www.kjsl.com/~dave/speedlites.html

Based on your figures, the 580EX would be 2/3 stop brighter than the 430EX at the 70mm position at full power. And it would be the same even at 1/4 power. Even though absolute light intensity-wise there may not be much of a difference, relative to each other, the difference would still be 2/3 of a stop.

[sinitry23]

What about the Vivta 285HV flash compare to the 430ex flash. Are they about equal in power to each other?

[msowsun]

Both the Vivitar 285 and Canon 430 are about the same power with a guide number of 140 feet or 43 meters.

[DoomMan]

The 540 is almost on par with the 580ex? huh?

[msowsun]

Yes, except the 540EZ will not do ETTL and will only work in Manual mode with DSLR's.

The 550EX is ETTL compatible with DSLR's.