Shutterstock Photographer Forum :: View topic

dubassy · Joined: 27 Jan 2006 Posts: 106

im normally over on the video side of this forum, but has a flash setup question i hoped someone with more experience might be able to help me with...

i make a lot of my videos, for instance dancers and people moving by firing the canon 7d in continuous mode, or 1 every second over a long exposure to make a kind of robotic jumpy movement..

i sometimes fire 1 flash in his setup, or use continuous lighting.

i was wondering about this setup with 2 flashes. i currently have the 430ex, and thought about adding the 580ex as master.

what i would like to know ( and i searched online a bit for this ) is can i use the the 580 on the camera as master which fires first and then the 430 firing as second curtain as slave, or does the slave have to fire at the same time??... i would like to have 2 different flashes from different positions during a long exposed shot ...

or could the slave be made to fire first and then the master fires the second curtain???

from what i was reading the master has to fire a pre- flash to make the slave fire this extra flash might ruin my idea..

i hope this makes a little bit of sense and someone might have some assistance!!

many thanks!

Mike Price · Joined: 06 Jun 2008 Posts: 2919 Location: South Wales

You can use a 580EX as a master, but the canon 7D has a built in controller whcih uses the built in flash as a master. So you could control two external flashes from the built in controller on the 7D. Alternatively you can set the 580Ex as a master and the 430Ex as a slave. The 7D manual fully explains both methods. If you det the slave on second curtain sync on the flash it should fire as you want.

Mike

markrhiggins · Joined: 28 Jan 2008 Posts: 2003 Location: Australia

Agree with whats been said. Also your 430 fires a pre flash anyway. The first flash is for exposure measurement. It just looks like one flash. This creates problems for people with canon trying to use the flash to set off optical slaves - usually the preflash triggers it not the main flash (the shutter is not open during preflash).