Although this video is based around using E-TTL with the new PWs ... it gives a very easy to understand explanation on how your shutter works in relation to flash exposure, sync speeds etc .. Thought it might be handy for people just getting into flash and that may have stumbled across the dreaded black verticals in their shots and may not have known why ..

http://www.pocketwizard.com/inspirat...roltl_optimiz/