Canon 580EX wireless flash questions

photobug

I have a 580EX flash on my 20D and am using a 420EX s a wireless slave. A couple of quick questions:

1. I've read about setting up flash ratios. However, it only seems to talk about ratios between REMOTE flashes in two different groups. How can I control the flash ratio between the 580EX master and the 420EX slave?
   (assuming that I really want to control the relative output of the flashes, and don't have the option of adjusting their distances from the subject to obtain the desired effect)
2. A trivia question -- when setting the 580EX so that its own flash is disabled (and it will act more like an ST-E2 wireless master), why is the flash being disabled indicated by "FF" in its LCD display? What the heck does "FF" stand for? (there's no clue in the 580EX manual)

thanks!
= dave

Bodley

photobug wrote:

I have a 580EX flash on my 20D and am using a 420EX s a wireless slave. A couple of quick questions:

1. I've read about setting up flash ratios. However, it only seems to talk about ratios between REMOTE flashes in two different groups. How can I control the flash ratio between the 580EX master and the 420EX slave?
   (assuming that I really want to control the relative output of the flashes, and don't have the option of adjusting their distances from the subject to obtain the desired effect)

thanks!
= dave

The on camera flash is in group "A" by default. So to set ratio's between on camera and slave set the slave to group "B". In my testing this is how it works.

photobug wrote:

A trivia question -- when setting the 580EX so that its own flash is disabled (and it will act more like an ST-E2 wireless master), why is the flash being disabled indicated by "FF" in its LCD display? What the heck does "FF" stand for? (there's no clue in the 580EX manual)
thanks!
= dave

Look to the left of the "FF" and I believe you will see a funky shaped small "o"

photobug

The on camera flash is in group "A" by default. So to set ratio's between on camera and slave set the slave to group "B". In my testing this is how it works.

Thanks, that would "make sense" ... although I thought I tried that to no avail. Also, the diagrams in the Users Manual refer to remote groups A and B in the diagrams (never any group letter next to the 580EX master flash) -- perhaps that's a documentation bug. Maybe I need to try it again, using this advice, under "controlled conditions" .

Look to the left of the "FF" and I believe you will see a funky shaped small "o"

Oh. I thought it might be something silly like that. (you'd think they could do better than that nowadays, using a fully-custom LCD panel!) But that does explain it nicely :-}.

= Dave

Bodley

Here's a couple of links relating to Canon Flashes:
http://photonotes.org/articles/eos-flash/
http://eosdoc.com/manuals/?q=ETTLRx

photobug

Here's a couple of links relating to Canon Flashes:
http://photonotes.org/articles/eos-flash/
http://eosdoc.com/manuals/?q=ETTLRx

Thanks much, Greg -- these are very helpful Canon Speedlite reference articles!