guide number of flash 580ex, 550ex, 540ez?

[christence]

anyone here knows the guide number of the following flash? (580ex,550ex,540ez) thanks!

Chris

[coreypolis]

if you want to get technical, every one is different, and every individual flash is different aswell. Almost all are under the stated iso/gn, sometimes by more than a stops worth.

I thought my 550 tested to be GN 110 at iso 100. But its been a while since I've tested it.

[FlashZebra]

anyone here knows the guide number of the following flash? (580ex,550ex,540ez) thanks!

Chris
The guide numbers for all of those particular flash units are about the same. I suspect the 580EX has a very slight, but likely insignificant edge.

But this chart should do the job nicely:

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

Buy the way, all I did was type "Canon Flash Guide Number" into Google and the link above with the chart was the 5th listing.

Enjoy! Lon

[Curtis N]

anyone here knows the guide number of the following flash? (580ex,550ex,540ez)58, 55, 54 meters, respectively (at ISO 100). Notice a correlation between the model number and the GN? ;)

To convert to feet, multiply by 3.3

Also be aware that these GNs only refer to when the flash is zoomed to its longest setting. The GN drops off dramatically when you zoom it wider.

The second sticky at the top of this forum has a link to a web page where you can find detailed specs and features of all of these units.

Please note that the 540EZ is not compatible with EOS Digital cameras.

[christence]

thanks! I figured out also by searching and exact site was post too. I know the 540ez is not compatible with the digital camera by TTL or ETTL but rather to manual it.

Chris