High Speed Sync (HSS) with a single speed light

Recently picked up the Yongnuo 622c and having a 6D that has a sync speed limit of 180 before getting those 'black bars', I was looking forward to testing it out. The goal really for me was to be able to shoot with a pretty wide open aperture like F/2.8 to get a nice DOF while still using off camera lighting in the daylight. You can also get this effect with a ND filter but I wanted to go with speed lights. Below are a few examples from some recent shoots..all shot at least an hour before sunset so the light was actually still pretty bright out (and all shot with the sun behind the model)

 f/3.5, 1/500, ISO 250

f/3.5, 1/500, ISO 250

 f/2.8, 1/350, ISO 160

f/2.8, 1/350, ISO 160

 F/2.8, 1/350, ISO 100

F/2.8, 1/350, ISO 100