Canon Presents Syl Arena's Primer on ETTL Flash Triggering

From the Canon USA YouTube Channel:

A quick primer on the differences between traditional optical-based wireless E-TTL, the exciting radio-based system in the 600EX-RT and how to control the 600EX-RT in a multi-flash set-up.

B&H carries the Canon Speedlite 600EX-RT Flash which currently qualifies for an $80.00 instant savings.