600EX-RT AF Assist light

I don't use the 600EX-RT but users complain that the ST-E3 doesn't have a focus assist and they can find no way to enable the off camera focus assist on remote flashes.

I think you have a faulty system/flash.

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Ian.
http://www.commercialphotographer.co.uk
Theres only one sun. Why do I need more than one light to get a natural result?