Canon 580ex's Manual mode

I'm currently using the Canon 5D with the 580ex as the on-camera flash (as well

as 2 480ex's as slaves). I have a question in relation to the "Manual flash

mode" of the 580ex.

On page 22 of the 580ex manual it states: "You can set the flash output from

1/128 power to 1/1 full power in 1/3-stop increments. Use a hand-held flash

meter to determine the required flash output to obtain a correct flash exposure."

I have just recently acquired a flash meter (Sekonic L-308s). Having never used

a flash meter before, what is confusing about the instructions in the 580ex

manual (page 22 and 23) are that I do not know how to translate the vernacular

of the Manual flash mode with the readings produced by the flash meter.

In other words, when you get back values of shutter speeds and aperture settings

(from the meter) how is that supposed to translate to the Manual flash settings

of everything between 1/1 and 1/128?

Any and all comments would be most appreciated!

K.

Hello,

A flash meter tells you the aperture you'll need, at the current flash power, to correcly expose a mid-grey subject that's at the same position as the subject.

As an alternive to altering the aperture, you can change the flash power.

1) First, select a sensible flash compatible shutter speed such as 1/160.

2) Next, select the desired aperture that will give you the DOF you require.

3) Set you're flash to an arbitary power setting. Maybe 1/2 power. Take a flash meter reading.

4) If the require aperture bigger than you're using (smaller number), then increase the flash power. If the required aperture is smaller, then reduce the flash power.

5) Repeat 3) and 4) until the flash power gives you the desired aperture.

Tim