Canon Speedlite 550EX as a dumb optical slave

[Doug Kerr]

We often have questions about using the Speedlite 550EX flash unit as a "dumb slave", optically triggered by, for example, a studio flash system. A common motivation is to use it as a background light or hair light.

If we try to do this with a widely-owned optical slave trigger unit, the basic Wein hot shoe type (type HS), we find it won't work. The 550EX is fired by the first burst from the studio lights, but then the system "locks up", and subsequent bursts will not fire the 550EX.

I presume that the E-I (voltage-current) curve of the sync input of the 550EX, after triggering, does not allow the SCR that is probably used in the Wein unit to "extinguish".

[Note to those who may wish to verify this by testing (I did after it had first been reported to me): with the system "locked up", if we give the Wein a "close range" burst from another flash, it will trigger the 550EX.]

I recently bought two of the Wein Micro Slave ("Peanut") trigger units (Type PN) for various uses in my studio configuration. It occurred to me that these doubtless have different components, and perhaps different circuitry, than the familiar HS unit, and perhaps they would not be susceptible to this "lockup" phenomenon.

I rigged up a test (I didn't have the proper adapter for the flash end so I had to be creative) and sure enough, the Peanut will reliably trigger my 550EX repeatedly.

So if you want to try this (no guarantee it will work on your 550EX, of course), what you would need is:

1. Wein "Peanut" optical slave unit:

http://www.bhphotovideo.com/bnh/con...ls&Q=&sku=63118&is=REG&addedTroughType=search

2. "Flash end" PC cord to hot shoe adapter:

http://www.bhphotovideo.com/bnh/con...ls&Q=&sku=95414&is=REG&addedTroughType=search

The Peanut slave has a prong that is functionally equivalent to the camera's PC terminal. It should plug into the PC plug on Item 2 above.

I have no idea how all this applies to the 580EX.

 

[Kevin Bjorke]

Sounds like you need to lay a stripe of gaffer tape over the Canon strobe's IR receiver window, to ensure that the Peanut is "master"

 

[Doug Kerr]

Hi, Kevin,

Sounds like you need to lay a stripe of gaffer tape over the Canon strobe's IR receiver window, to ensure that the Peanut is "master"

Well, for one thing, the 550EX will not be set to Slave mode, so its command receiver wouldn't be active.

And in any case, that receiver will not respond to a non-coded burst (one not coming from a 550EX or 580EX in Master mode or an ST-E2).

Best regards,

Doug

 

[Kevin Bjorke]

Oops! And here I thought gaffer tape could fix anything.

As an aside, I've noticed that in slave mode I can use the 550EX set to manual exposure with the ST-E2 controller on non-EOS cameras. In bizarro world, I suppose you could have the Canon trigger a slave on your studio units, rather than the other way 'round.

 

[Sean DeMerchant]

Using a radio slave rather than optical slave firing mechanism will solve it. I use this for macros in the field with a 550-EX plus umbrella on a tripod (light stands fall over in the slightest breeze and break umbrellas) without absolutely no lockup issues.

 

[Tim Armes]

Can someone please tell me where I can buy a hot shoe adapter with 3.5mm socket in Europe (prefereable UK or France)?

Thanks,

Tim

 

[Bart_van_der_Wolf]

I suppose you could have the Canon trigger a slave on your studio units, rather than the other way 'round.

Yes, the camera flash will trigger the studio flash, or the ST-E2 will if the studio flash has IR slave sensors. So one could use an ST-E2 to trigger the lot, studio gear + Speedlite used as accent lights, all together.

Bart

 

[Doug Kerr]

Hi, Bart,

. . .or the ST-E2 will if the studio flash has IR slave sensors.

Are we sure the coded signals the ST-E2 sends will be accepted by a studio flash with what ever kind of IR sensors you are speaking of? I have always assumed that the studio flash IR control systems used a proprietary protcol, or else the receivers just responded to a dumb pulse.

Best regards,

Doug

 

[Bart_van_der_Wolf]

Are we sure the coded signals the ST-E2 sends will be accepted by a studio flash with what ever kind of IR sensors you are speaking of?

Apparently not reliably so. On my Multiblitz monoblocks their slave sensors respond to visible flash and to IR flash. This afternoon things worked flawlessly, with the ST-E2 triggering both the Speedlite and the studio flash in sync, tonight it didn't ...

Now all I can get to sync with the studio flash is an on camera 550EX on manual. Now the ST-E2 only triggers the 550s (slave mode) in sync, and the studio flash out of sync. bummer.

I have always assumed that the studio flash IR control systems used a proprietary protcol, or else the receivers just responded to a dumb pulse.

That may be different between brands/models, so I could only verify it for my own setup.

Bart

 

[Sid Jervis]

Can someone please tell me where I can buy a hot shoe adapter with 3.5mm socket in Europe (prefereable UK or France)?

Thanks,

Tim

Tim I do not know if you have sorted this yet.
You can buy these units from, www.theflashcentre.com

For a Canon 580ex you need a Kaiser 1301 hotshoe adapter which is £13 ex vat, from TFC.
There may be other companies.

Cheers

 

[Ben Rubinstein]

Tim, I'm using simple adaptors from Staples in the UK for my radio slaves, I'm sure with enough cobbling together.....

 

[Ben Rubinstein]

Not staples, my bad, um what the hell is that high street electronic componets place called?

 

[Tim Armes]

Tim I do not know if you have sorted this yet.
You can buy these units from, www.theflashcentre.com

For a Canon 580ex you need a Kaiser 1301 hotshoe adapter which is £13 ex vat, from TFC.
There may be other companies.

Cheers

Hi,

Sorry, I've only just seen this.

TFC tell me that they'll only sell them to people who buy radio triggers from themselves.

I'll make no further comment, because it might be rude.

Tim

 

[Tim Armes]

Tim I do not know if you have sorted this yet.
You can buy these units from, www.theflashcentre.com

For a Canon 580ex you need a Kaiser 1301 hotshoe adapter which is £13 ex vat, from TFC.
There may be other companies.

Cheers

Hi Sid,

I've finally found another supplier of this component, thank you. The Pro Center has them in stock for £6.80 ex VAT:

http://www.procentre.co.uk/consumables_prices.html

I've ordered a couple. They tell me that they come with a little cord ending in a PC plug. I'll either need a PC plug to 3.5mmjack plug converter, or else I'll chop off the plug and put on a 3.5mm jack socket.

The base of the adapter is metal. I remember reading that this can cause problems with Canon flashes - is this true?

Thanks,

Tim