Canon's latest flash the 600EX-RT with built in radio-based wireless triggering that gives you full E-TTL  and allows you to control 15 600EX-RT slave units (NO MORE LINE OF SIGHT).  In my opinion this is a huge leapfrog over the competition.  Yes everybody is talking about the 5D Mark III but this is the best new product – wow Canon!!! – you did listen to your customers and what an awesome response.To get the most out of these units you will need to marry the unit with either the %D Mk III or the new 1DX.  You can arrange the remote flash units in groups for a total of five and have total control over each group.  What is even more impressive is a flash head zoom range from 20mm to 200mm.Also impressive is Canon's ST-E3-RT wireless transmitter, which offers all the triggering functions built into the flash without the need for one unit on the camera.I am providing a link to Syl Arena’s blog where he provides his first impressions of these fabulous units.  Click here.