580ex fire when master?

[IanWorthington]

The 580exii manual says the master has to be set to not fire to control slaves, but I'm being told this is not correct.

But how then do I control its power? Does it become a group A/B/C flash, or is its power controlled some other way?

i

[SeedyBee]

The Master can be set to fire to contribute to the actual exposure, or not. Either way, slaves can be controlled.

The Master can be set to use E-TTL and use a ratio between groups A and B. Optionally, a Group C can have its own FEC set in relation to the main exposure, to use for rim or backlights.

Or, the Master can be set to Manual and set Groups A, B and C to specific power levels.

In either case, the slaves will adopt the settings that the Master tells them to use. Start the slaves in ETTL mode, and see them change.

If your camera body has Flash Control menus, it is easy to see how this can all be set up simply.

[IanWorthington]

Thanks Seedy.

Looks like in ETTL mode the master is in the A group, yes?

In Group C, does the FEC for that need to be set on the slave itself or the master? If on the master, how then do I adjust the FEC for the image?

(30D here: no on-camera menus.)

Ian

[SeedyBee]

Yes, the Master is always in Group A, but if the main flash is turned off, it does not participate in the exposure for that group.

FEC for Group C is set on the Master. It involves holding the Zoom button and then pressing various other buttons, and you should follow the manual instructions. Timeouts can catch you, so be prepared for a learning curve.

FEC for overall A and B is set either on the flash by pressing the Set button and dialling a figure, or on the camera top buttons. Any value set on the camera will be ignored if a value is set on the flash. The flash provides 1 stop more either way.

[curtscamera]

It may be helpful to disable the auto power-off function on the speedlites. On my 5DII the first item on my custom menu is the flash control settings. It's pretty easy to manually control power to the Master 580Ex-II mounted on camera and to the slaves in group b and c through the menu on camera.

[IanWorthington]

Thanks guys.