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New Contributor
Posts: 3
Registered: ‎06-13-2013
Accepted Solution

Can I wirelessly use a 430 EX II as a slave with the built in flash of the EOS T3i?

I have a Rebel EOS T3i.  According to its manual, pp 191 ff, I can fire a remote speedlite wirelessly from the camera.  I get an error message that the speedlite can't be found even though I have set up my speedlite 430 EX II according to its manual directions, pp25 ff.  Thanks for your help

Esteemed Contributor
Posts: 3,800
Registered: ‎06-11-2013

Re: Can I wirelessly use a 430 EX II as a slave with the built in flash of the EOS T3i?

Yes - the 430EX II will function as a slave and the T3i (but not the T2i or earlier) can remotely trigger the speedlite.


It's a bit tricky and can be confusing.


First... set the 430EX II in the right mode.  Press-and-HOLD the "Zoom" button for about 2 seconds or so.  This activates a menu that lets you put the flash in either a single-fash mode vs. remote "slave" mode.  Use half-circle buttons to toggle it to read "slave".  Press the "set" button (in the middle of those half-circle shape buttons.)  I don't happen to have my 430EX II handy, but it should default to Slave "A" and Channel "1".  


Now for the camera.


On your camera menu, the left-most tab (which we'll call "Red Camera #1" to distinguish it from other tabs) has the "Flash Control" as the last option on that screen.  Incidentally for cameras with a built-in popup flash, the menu is labeled "Flash Control".  For cameras that do NOT have built-in pop-up flash, that same menu is called "External speedlite control".


On that sub-menu (Flash Control), make sure "Flash Firing" (the top option) is set to "Enable" or  "CustWireless" -- it must NOT be set to "disable" or nothing will work.


You will see a menu options for "External Flash func. setting" (and also "External flash C.Fn setting".)  IGNORE THESE!  These are ONLY for flashes which are in the camera hot-shoe and do NOT control wireless remote flashes.  This is likely where you were getting confused.


Next go to "Built-in flash func. settings" where, ironically, you get to control how your camera communicates with your REMOTE flash (yes, I realize that's not the most intuitive place to put it.)  It turns out that it's your INTERNAL flash that is responsible for communicate with any REMOTE slave flashes.  The optical wireless actually uses visible light (a lot of people presume it's an infrared communication -- myself included -- I ultimately learned that was incorrect and it is actually the visible light of the flash itself.  It sends out communication to the remote by rapidly pulsing codes to tell the remote flash what to do.  All this happens before the image is exposed and you'd swear the flash only blinked once... but it turns out it's actually quite busy pulsing away to communicate.)


In the "Built-in flash func. settings" menu there are a number of things you need to set. 


If you set the Built-in flash mode to "EasyWireless" it will gray out many other settings... basically the camera will automatically decide what it wants to do.  I think the only setting not gray is the channel number (which needs to match the channel number on your flash.  The purpose of channel numbers is to allow you to shoot at events where other photographers are also using wireless flash and not have conflicts where they're triggering your flashes and vice versa.


If you set the Built-in flash mode to "CustWireless" it allows you to set many other options.  CustWireless offers the most control.  It is ultimately probably the mode you'll use the most once you get used to remote speedlites.


In CustWireless mode, the "Wireless Func." menu option becomes available.  This option lets you decide if you want (I'm taking these out of order for simplicity of explaining):

a)  both internal and external speedlites to fire as one group (external flash icon,  a PLUS sign (+) and the on-camera icon)

b)  both internal and external speedlites to fire but allowing you to control the power RATIO (external flash icon, a COLON symbol (Smiley Happy and the on-camera icon means "ratios" can be customized.)

c)  only external speedlites (only the external flash icon is on that option - no on-camera icon.)


I want to mention something about that external-only option because it confuses most people at first.  The camera communicates with the slave via the on-camera flash.  The on-camera flash pulses rapidly to send instructions to the remote flash units.  This means that in order to use slave-flashes, the on-camera flash must be raised (in the popped-up position).  If you ask for external flash only (no on-camera) the on-camera flash will only pulse instructions BEFORE the camera shutter opens to take the exposure.  When I first started learning about external speedlites, I saw the on-camera flash fire and thought my settings were being ignored.  Not to worry... when you check your images you will see that there was no light provided by the on-camera flash DURING the exposure... all that flashing happens before the shutter opens.   Everything happens so fast that you'd swear all the flashes only fired once... but in reality they actually do a lot of "talking" before taking the picture but this happens incredibly fast.


And one last comment... since the camera communicates via the optical (visible light) flash to talk to the remotes, it is important the the lower-body of your 430EX II can "see" the flash on the camera.  In small rooms it doesn't really matter where the lower-body is pointed... it'll notice the pulses of light from the on-camera flash.  But in large rooms or outdoors the lower-body of your 430EX II (where the receiver is located) wont get any reflection from walls, etc.  In these situations, just rotate the lower body of the 430EX II so that it is facing the on-camera flash.  You can then swivel the head of the 430EX II to point wherever you need it.  The 430EX II will fire even in full daylight as long as it can "see" that on-camera flash.


Here's a video that may help you:


Tim Campbell
5D III, 5D IV, 60Da
New Contributor
Posts: 3
Registered: ‎06-13-2013

Re: Can I wirelessly use a 430 EX II as a slave with the built in flash of the EOS T3i?

Many thanks for your help.



New Contributor
Posts: 1
Registered: ‎12-05-2015

Re: Can I wirelessly use a 430 EX II as a slave with the built in flash of the EOS T3i?

[ Edited ]

Very detailed explanation.  Thanks.


Can a G5X also connect to the 430exII as a slave flash?  The built-in flash in anemic and it has a hot-shoe.  Unfortunately, most of Canon's flashes are much larger and heavier than the camera itself-- it would be best to use the flash remotely.


But the menu on the G5X seems to be much more "Powershot" level than the cheaper, more capable T3i.  The manual suggests the 430EXii has very limited connectivity.

New Contributor
Posts: 1
Registered: ‎12-16-2015

Re: Can I wirelessly use a 430 EX II as a slave with the built in flash of the EOS T3i?

Thank you for the explanation about the external-only flash mode and the light pulsing PRIOR to shutter release.  Unfortunately, the manual that came with the camera is woefully lacking.  I am using a Speedlite 430 EX II with a newly purchased T6s.  When I saw the built-in flash fire, I thought I got a lemon.  

Product Expert
Product Expert
Posts: 810
Registered: ‎10-17-2012

Re: Can I wirelessly use a 430 EX II as a slave with the built in flash of the EOS T3i?

Hello jrseatown, 

The PowerShot G5 X can wirelessly control an off-camera Speedlite EX supporting Slave mode only when used with a Canon Speedlite Transmitter ST-E2 or ST-E3-RT.  The PowerShot G5 X wouldn't be able to use native control functions to operate an off-camera Speedlite remotely without the use of a Speedlite Transmitter.  

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New Contributor
Posts: 1
Registered: ‎08-27-2018

Re: Can I wirelessly use a 430 EX II as a slave with the built in flash of the EOS T3i?

your article is excellent and helpful. It addressed the same issue i had and was wondering why the internal flash fires together the external when only latter is selected.

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