Canon flash heads (master/slave)

Moonhawk

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Hi

I have two canon flash heads - a 580EX and a 430EX.

I have set the 580EX as master and the 430EX as slave and with the 580EX on camera and the 430EX off camera - they both fire in sync, no problem.

However - I have just bought a radio trigger set (1 transmitter and 1 reciever - a second reciever is on backorder). I was experimenting with them tonight. If I hook up the radio reciever to the 580EX acting as master and set the 430EX to slave - the 580EX flashes when I activate the radio trigger - then the 430EX flashes about 1/2 a second later (triggered presumably by the 580EX's infra red). I dont understand why there is a delay though :shrug:

Does anyone have any ideas.
 
Stab in the dark but it is something to do with the fact that the IR the 580 uses is generated when the flash in on camera and when you are firing it via radio trigger the IR is not working correctly?
 
Yeh - that was my guess - but i'm having a hard time understanding why that would be the case. If it hadnt fired at all, it would make sense - but to fire with a delay is a little weird.
 
may be that the flash itself from the 580 is triggering the 430 and there is a fraction of a second delay in this rather than the IR doing the job if it were on camera?

I am sure there is someone here who will pop along shortly with the knowhow to answer this :)
 
It wont cause me too much of a problem once I have my second reciever in hand - i'm just interested in knowing what causes this (and I was looking forward to having a play with both flashes :D )
 
How are you activating the radio trigger?
 
generic flash triggers do not have the required coding to work with ETTL... If you use flash triggers you must work in manual mode, and have one on every flash head ... you must not set master and slave.
 
How are you activating the radio trigger off the camera?
 
Terrywoodenpic said:
generic flash triggers do not have the required coding to work with ETTL... If you use flash triggers you must work in manual mode, and have one on every flash head ... you must not set master and slave.
Click to expand...

Like Terry says, unless you are using high-end dedicated Pocket Wizards or something, you must switch everything to manual.

And of course, you lose all that wonderful functionality and automation that those nice Canon people have given you. With your IR equipped flashes, the only reason to consider radio triggers is if you run out of range.

(I have heard that the 430EX (Mk1) emits radio frequencies that can upset some radio triggers. Not sure of the details - google?)
 
LOL - have you still got the 580 as master? The trigger now acts as the master and you have to put the 580 and 430 as slaves.

I have a ST-E2 that I use to trigger my 580 and 420 just fine.
 
Byker28i said:
LOL - have you still got the 580 as master? The trigger now acts as the master and you have to put the 580 and 430 as slaves.
Click to expand...

Not sure I totally understand. If I set the 580EX to slave - it wouldnt trigger the 430EX via the infra red.

This is how I figured it would work.

The radio reciever is plugged into the pc sync port of the 580 EX, with the transmitter on the cameras hotshoe. I assumed that this would work just like having the flash on an off camera hot shoe with a PC cable running between the camera and the flash.

At this moment in time I only have the one radio reciever (the second being on back order) so I was thinking I could turn the 580EX on as master and trigger the 430EX as a slave unit via the 580EX's infra red trigger - thereby allowing me to use both flash units off camera (so far I dont see anything wrong with this theory). Camera triggers 580EX via radio , 580EX triggers 430EX via infra red.

It almost works as I had intended - both flashes do fire, but there is a delay between the 580EX and 430EX firing - probably 1/2 a second.

I know the ETTL function wont work with these triggers. I was aware of that before I bought them and always intended to use the flash units in manual mode off camera. However the in-built infra red trigger of the 580EX isnt dependent on the ETTL function and works just fine in manual mode.

Having googled a bit last night - it has been suggested that this problem is in fact due to the radio triggers pulse length being too short to trigger the infra red of the 580EX. There is a workaround involving soldering a capacitor onto a hotshoe in order to lengthen it.

http://www.flickr.com/groups/strobist/discuss/72157604646801907/

TBH - I think i'll just wait until my second reciever turns up - I was just eager to have a play with both units off camera.
 
Hi,

I replied to a similar question on another forum a while ago which may be of use here ...



"I didn't know the answer to this so I've had a bit of a play with the kit I have to hand, which is similar but not identical to yours. I used a 580EXII and a 430EX (Always set to their lowest power settings in manual mode).

I tried the following combinations and took photographs of the flash heads facing the camera:


#1 - 580EXII, set as master, attached via OC-E3 and 430EX set as slave

This worked just as if the 580EXII was on camera, as you'd expect. I could sync up to 1/250th of a second and beyond that I could use high speed sync for shutter speeds up to 1/8000th of a second. I did notice that the brightness of the flashes appeared to reduce when using HSS (As I have read about before), presumably so they can fire multiple times over the very short exposure time, so I don't think this is the magic bullet required to overpower the sun on bright days.


#2 - 580EXII, set as master, triggered via Cactus V2 and 430EX set as slave

This wasn't quite as successful, but the results were interesting. I found that I could sync the 580EXII up to 1/250th of a second but at this speed the 430EX didn't appear to light up. I found that I needed to extended the exposure time to 1/125th of a second before I could see the 430EX flash too. I can only assume that the longer exposure is required due to the time taken for the Cactus trigger to talk to the receiver and then for the 580EXII to tell the slave 430EX to fire.

This is worth the OP thinking about as he may well be limited to syncing at 1/125th of a second if he chooses this method.


#3 - 430EX and 580EXII both triggered via Cactus V2 (Neither flash was a master / slave)

This worked better than the previous method as both receivers could respond to the trigger quickly enough to sync at 1/250th of a second. If I went to 1/320th of a second (Which is beyond my 30D's sync speed) I found that approximately the bottom quarter of the image was not exposed to the flash.

I read about this actually being useful on David Ziser's blog (Digital Pro Talk) recently. He showed that if the area being lit by flash was in the foreground, at the bottom of the image, he could push the shutter speed beyond the sync speed of his camera by turning the camera upside down. This effectively moved the "dark region" of the sensor, that is not exposed to the flash, to an area of the scene that would not be exposed to the flash anyway (E.g. the sky). This was useful when trying to control the sun on a bright day as he could go to 1/320th or 1/400th if the scene allowed for it.

Thinking about it, there is nothing stopping the OP's 420EX being set to slave mode, as he says that's the only way he can set the power manually, and still being fired by the Cactus receiver - so this may be the best (In terms of sync speed) and cheapest solution (Relative to the ST-E2, pocket wizards etc).


#4 - 430EX and 580EXII both triggered via ST-E2 (Both flashes were set to slave)

Obviously, this worked fine to 1/250th and again I could use HSS to go up to 1/8000th (At the expense of apparently reduced power output from both flashes).


So, my recommendation is probably to go for a Cactus V2 trigger and buy two receivers. It's a wireless solution which would always be my preference. I was still able to sync at 1/250th (Although I was only working the length of a dining room table so maybe longer distances will affect this) and the 420EX can probably still be set to slave mode to give access to the manual power settings (Although I can't guarantee it, it worked on my 430EX).

Hopefully the OP finds this useful."



So, if I understand correctly, #3 is what you'll have when the second trigger arrives and #2 is what you're trying at the moment. The only difference between what you're doing and what I did was that you are triggering the 580EX via PC Sync whereas I connected the cactus receiver to the 580EXII via the hotshoe. I don't know if this is an important difference but it may be worth you trying it out via the hotshoe.

Finally, the only time I have seen a slave flash fire approximately 1/2 second after the master flash is when I'm test firing the master flash and the flashes in the group A fire and then group B fire shortly afterwards. A possibility is that your setup is acting as if the 580EX is firing a test shot and your slave is in group B? That's just a guess but you might try making sure your 580 and 430 are both in group A?

Let us know how you get on.

Cheers
 
Curiosity got the better of me so I've copied your setup and found that I get exactly what you are getting if both the 580EXII and 430EX are in ETTL mode.

If you hold the mode button down for a few seconds on the 430EX, it puts it into manual mode and then there isn't the 1/2 second delay.

If you put the 580EXII into manual mode then it doesn't fire at all. However, if you use the cactus receiver on the 580EXII hotshoe (rather than via the pc sync), then it does fire and correctly fires the 430EX slave.

I could only manage to get a sync speed of 1/100th today which I can only put down to flatter batteries since I did the test last time around.

Hope this helps.

Cheers.
 
ksten said:
Curiosity got the better of me so I've copied your setup and found that I get exactly what you are getting if both the 580EXII and 430EX are in ETTL mode.

If you hold the mode button down for a few seconds on the 430EX, it puts it into manual mode and then there isn't the 1/2 second delay.

If you put the 580EXII into manual mode then it doesn't fire at all. However, if you use the cactus receiver on the 580EXII hotshoe (rather than via the pc sync), then it does fire and correctly fires the 430EX slave.

I could only manage to get a sync speed of 1/100th today which I can only put down to flatter batteries since I did the test last time around.

Hope this helps.

Cheers.
Click to expand...

Yep - that works a treat - both flashes fire in sync. After metering the light output - the 580EX on ETTL mode set to 0EV seems to be firing at at the same intensity as the 430EX set to manual at 1/16.
 
I'd put both flashes in manual to give you full control of the light output and then attach the cactus receiver to the 580EX hotshoe so that it still fires.

Cheers.
 
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