Dark Alley way...1 slave!

[Matt30D]

I want to take a really cool picture of a person in a dark alley way, with a slave strobe (430ex) as my light sourse...off to the side. I will sync it to my 580 EX....can I trip the 430 without the 580 going off to ruin the affect?

[Dermit]

Yes and no... You can tell the 580 to not fire and just trip the slave... but a little bit of the preflash from the 580 will go off while the shutter is open. So depending on your settings this preflash might be too weak to effectively be a part of the exposure... but it might be if your settings are such that it can 'see' it.