Hi, I have a 5DII and a 580 EXII flash. It was my first time using it extensively this weekend outdoors shooting a wedding and when I was shooting in AV mode wide open, if the shutter speed was faster than 1/180 sec, the shot was overexposed. I did a little research and learned about my shutter sync speed. I switched it to High Speed in the camera functions just playing around outdoors and shooting wide open is now possible with really fast shutter speeds. Is there any disadvantages to keeping it on High Speed shutter sync?
Thanks 

