30 March 2009

Speedlite masters and slaves

For some photographers, the concept and details of wireless Speedlite flashes is simple and they just get on with it. However for a large number it's a minefield designed to trap the unwary, and make photography with flash absolute hell.

Today we'll kick off with a short list of Canon flashes that can be used in a wireless Speedlite flash system. All kinds of wireless flash systems need a single leader to tell the rest of the flashes what to do, in Canon terminology this is the master. Following the obvious all the subservient flashes employed in the wireless flash setup are known as slave flashes.

All the following models can act as masters, controlling the slaves;
  • Speedlite 580EX II
  • Macro Ring Lite MR-14EX
  • Macro Twin Lite MT-24EX
  • Speedlite Transmitter ST-E2
  • Speedlite 580EX
  • Speedlite 550EX

All of the following models can act as a slave flash
  • Speedlite 580EX II
  • Speedlite 430EX II
  • Speedlite 580EX
  • Speedlite 430EX
  • Speedlite 420EX
  • Speedlite 550EX

Seems mostly typical that the current models of flash that are masters outnumber the slaves.

One question that some people ask is how many slaves can you control from one master. Generally Canon suggests the limit is seven slaves for each of the three groups that some of the masters can control. However in practice more than this is possible, and blabpictures have successfully managed to trigger 11 slave speedlites from a single master. Typically the limits are practical rather than system specific, think how much space you need to put up 21 lights and aim them at the photo subject and then add in the range of the pulsed light transmission and you can see that for most practical purposes the system will suffice.

You should also check out the previous post about using the MR-14EX and MT-24EX as a master with custom function 5 on blabpictures.

To set the master / slave function the older flashes have a nice easy to find switch, the latest generation 580EX II and 430EX II make it really tough and use a scheme where you press and hold the Zoom button for about five seconds - Canon please can we have the switch back?


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