High-speed-sync flash is a feature on both the 430EX and 580EXii speedlights. However, I seem to only be able to get high-speed-sync flash to work when it’s sitting in the hotshoe. As soon as the 430EX or 580EXii are triggered remotely as slaves, high-speed-sync longer seems to be an option. I’ve read the manuals and scoured the Internet, but I can’t find anything that confirms this. Can anyone confirm this for me?
To explain the problem from a more practical perspective, with the speedlight sitting in the hotshoe with high-speed-sync on (on a Canon 7D II in Manual mode with shutter speed set to 1/800) the speedlight fires and the photo is taken at 1/800. As soon as I take the speedlight off the hotshoe, however, and set it to work as a slave, high-speed-sync is no longer an option, and (on the Canon 7D II in Manual mode with the shutter speed set to 1/800, with the popup flash set as the trigger for the slave) the sleedlight fires and the photo is taken at 1/250, the default max flash sync speed.
So I’d like to know two things:
1. Can anyone confirm that off-camera high-speed-sync is not generally possible (without a more special trigger)?
2. What special trigger should I buy that would allow the off-camera high-speed-sync to work on either of these two speedlights (preferably the 430EX)?