Was reading an article the other day talking about high speed sync (HSS), can't remember the link. The author was explaining HSS and I found it answered many questions I had. Basically what I got out of it was that he has his flash permanently set to HSS. If you're shooting at speeds below the critical speed (1/250s for my setup), the camera/flash just behave as is HSS is not set. But if you shoot over that speed, HSS kicks in.
So I'm interested to hear what others have their flashes set to.
[edit]
Found the link to the article - http://www.rpphoto.com/howto/view.asp?articleID=1026![]()
I have my flash set with HSS on always


