# Canon 90EX Speedlight functions as a Master



## oneguywithacamera (Jul 24, 2012)

As I was reading some info on the new Canon M, I came across a claim that the 90EX can in-fact function as a master unit for Canon&#8217;s _*optical*_ driven ETTL-II system. Well, of course I had to double check that fact, since it&#8217;s MSRP is only $149. Previously the only way to get master functionality was to buy a ST-E2 (~$250) or a 508EX II (~$450). Sure enough, Canon USA states &#8220;&#8230;and can control multiple flash units for advanced, creative lighting effects.&#8221; That&#8217;s pretty cool, and can start to give off-camera speedlighters a much lower cost of entry for a multiple flash master.


I haven&#8217;t found a link to the manual for the 90EX, but judging by the only control being on the unit is the power switch, the 90EX can only be an on-camera flash or master controller and not a slave itself. This isn&#8217;t a big deal really, as the guide number of the 90EX is a diminutive 30&#8242; &#8211; compared to a 430EX II&#8217;s 141&#8242;. I&#8217;m also not sure if the master function is only controllable via a 2012 camera&#8217;s menu system or if it will work on pre-2012 bodies.


In any case the 90EX is a bargain master controller for IR ETTL-II control if that's the way you want to go.


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