Using multiple wireless speedlites

You can use the 430EX or 580EX II wirelessly to create a multilighting effect much like you would have in a professional studio lighting setup. To do so, you need to set a single flash attached to your camera as the master unit and set the receiving flash(es) as slave units. The master flash utilizes ETTL to obtain the best-possible image. This capability should help you be able to extend flash range, and, if configured properly, overcome some of the limitations caused by the Inverse Square law.

The 580EX II is the only unit that can be used as a master or slave device, while the 430EX can be used as a slave only. The 270EX cannot be used as either. The Macro Ring Lite MR-14EX, Macro Twin Lite MT-24EX, and Speedlite Transmitter ST-E2 can also be used as master devices.

You can use virtually any flash exposure capability in this manner, including FP flash, FE lock, FEB, manual flash, and even the stroboscopic settings. All settings are automatically transmitted from the master to the slave units, meaning you only have to change settings on your master.

To turn a Speedlite into a master unit, you either flip a switch at the base of the flash that you manually switch from normal to master or slave settings, or in the case of the 580EX II, you use the Speedlite’s LCD panel by holding down the Zoom button for two seconds for access. In all cases, you need to have your master flash set to the ETTL setting.

If for any reason there are multiple Canon wireless flash systems operating in close proximity to one another, you can also change the wireless channel on which yours operate so they aren’t on the same channel as others in a different system.

To be able to set the slave flashes in the proper location, you can either use the stand that comes with the flash (it slips onto the hot-shoe mount), or you can set the flash onto a tripod using the tripod socket on the stand. You need to position the lower body of a slave flash facing toward the master unit so that it can receive the transmission; any obstacles between master and slave can interrupt the signal and prevent the slave flash from firing.

If you have two or more slave units, you may want to fire them only and not the master unit, which is possible because you can set the master unit flash to Off using the LCD panel. This may provide a better simulation of standard studio lighting for you, where you would typically not be using a camera-mounted flash. Note, however, that the master unit will still fire a preflash signal to be able to transmit the wireless information.

With the current units, you can set multiple slave units using flash ratios, which simply means different units can fire at different flash power settings. This ratio number is what appears in the LCD panel where you can select your setting. The numbers on the bottom are the 1/2-stop increments, which are settable by selecting the dot that appears in the LCD panel.

You can have up to three groups of slave units, each containing one or several flashes, indicated as groups A, B, and C. You can control the ratios in all three groups, although C is used only for background light; you set the flash ratio output for each slave unit group from the master.

If your camera has a depth-of-field (modeling flash) preview button, you can use this to fire your entire flash configuration to see how your flashes will fire when you actually take a photo.


In some cases, you may be able to bounce the signal off of a reflective surface, such as a white wall.


You can test your flash configuration with the master unit off of the camera by pressing the Pilot button (the red light). The slave unit(s) will still fire, but after a momentary delay.

Category: Flashes

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