7D AND SLAVE FLASH

+1

And with Light/IR Canon Wireless it's worth thinking about the detail of the Controller fresnel-to-Ex slave Sensor window in some detail.

What you might call environmental bounce can help get the signal 'through'. OTOH, with my 7D in portrait orientation (shutter button up), I frequently found that control & triggering of lights cam-right was less reliable than to those cam-left. It was the lens/lens hood getting partially in the light path.