There was an earlier poster who wanted to know how one flash would compare to another.


I often wonder how my 580EX at full power (manual) compares to my speed light at full power.


Sure I can talk about stops of light, but I would like to measure the output in lumens or something


and directly compare it.


I have a sekonic light meter but I would like to know my strength of flash in my arsenal as I plan


my shots.


Ie. What manual power on my 580 EX II equals 1/2 power on my speed light.


Ideas? Certainly there is a meter than measures ambient light and could also measure the flash


output.