I have been looking at the instructions for the speedlite 580ex here for any idea how to fire the flash from the built in camera flash, but it has not helped.
Does anybody know if it is possible to fire it with a cameras in built flash?
edit
I'm not sure if this has been read incorrectly. If I am not mistaken the flashgun can recognise when a flash goes off (a peak in light) and fire its own flash also?
I was watching a video on youtube where a buzz lightyear camera fired a remote flash gun, by its own flash firing.