Zack is famous for his OneLight portraits. I read about Zack in someone’s blog a long time ago and followed his blog for quite a while.
In this video from Creative Live, Zack discusses the relationship between flash power and aperture.
Zack and Creative Live have produced a series of videos that can be purchased based on his 3 day workshop. Almost like being there, but you get the added flexibility to repeat any portion of the workshop that you didn’t quite catch, or that you are having difficulty grasping.