Wireless Flash/Master Off?

[martcol]

Help me with this please?

I'm practising (still!) with two flashes (a 550 EX on camera and 420 EX slave). I can work out with the manual how to turn the 550 off (Master off) but it still flashes. Is this how it should be? I notice a difference with the shots i.e. with just the slave on the subject is definately lit from the side. However, it seems to me the Master should go right off? I thouhgt that all the info would be conveyed through the wireless signal or, does the 550 still need to flash to tip the 420 off?

I'm also shooting in Av with f5.6 and High speed sync set on the flash.

Thanks

Martin

[Littlebike]

I think if you turn the 550ex to TTL instead of ETTL you will get the result you are looking for.

Or, you could turn the 550ex down 3 stops by using flash compensation and it will then only act as a fill flash allowing the 420 to be the predominant light source.

[martcol]

I'll try that Littlebike, but what about the 550 turning off and is it not better with ETTL? As I said, there are differences in the shots with the 550 EX turned off (brighter on one side) and the manual indicates that the master should turn off. Is it cos I'm using a 420 to slave rather than another 550?

Cheers!

Martin

[DaveG]

martcol wrote:
I'll try that Littlebike, but what about the 550 turning off and is it not better with ETTL? As I said, there are differences in the shots with the 550 EX turned off (brighter on one side) and the manual indicates that the master should turn off. Is it cos I'm using a 420 to slave rather than another 550?

Cheers!

Martin

Turn on the 550EX. Push mode until ETTL comes up. Push SEL/SET. Keep pushing it until after "CH". At this point the icon of the flash on the LCD should be blinking. Use the minus (-) to turn off the 550's flash tube. The LCD should now show the lightning bolt blinking next to the flash icon. This means that the flash tube on the 550 is OFF. If the lightning bolt is constantly on then the 550's flash tube will fire.

Be careful to go past RATIO. You can turn the ratio to OFF and it may occur to you that now you've turned off the flash tube, but this isn't the case.

There is still going to be a flash pulse that comes out of the 550. This is the E-TTL pop that tells the other flash - the 420EX in this case - how to behave.

There is NO TTL setting on the 550EX or the 420EX only E-TTL.

[martcol]

So DaveG, thanks. I did exactly what you described and you must be psychic because I was getting the on/offs confused. What you seem to say is what I suspected, that the 550 will still flash. I haven't got a malfunction then? phew! :)

[leony]

Actually, there is a custom function on 550EX that lets you set the flash to TTL mode, instead of E-TTL. But all digital cameras only work with flash in E-TTL mode, so you're out of luck. I use mine when shooting in a studio turned down to lowest power in manual - to only get one flash - which trips the light slave on the studio strobes.

~ Leon.

[martcol]

I've just had an email from canon support on this - here's the meat of their reply:

Thank you for your recent enquiry regarding your Canon 550EX flashgun. If the 550EX has been set to 'Master Flash OFF', it should not fire a flash and simply trigger the slave unit. (In this instance the 420EX). If the 550EX is still flashing, we recommend you check that having set the master flash to 'OFF' you press the SEL/SET button afterwards to ensure it has been set. If it has been correctly set to 'OFF' then 'Z' will blink on the 550EX display. (As per p.104 of the 550EX user guide.)

what they say isn't what happens. Any ideas?
I did of course, RTFM and followed it's advice!

Thanks

Martin

[robertwgross]

Let's just make sure that we are absolutely clear on the controls.

On the 550EX, the bottom switch is OFF-MASTER-SLAVE. Above that on the right is Off-On-SE. Above that on the left is Mode.

You're trying to shoot E-TTL, right? And that is displayed?

How is the 420EX set?

---Bob Gross---

[martcol]

Thanks for your interest Bob, I'm sure that I did everything according to the manual. I'm pretty new to this so generally go for overkill on the research before trying things out. Your description of the switches is spot on. I'm going to go through it all again tomorrow and make a careful note of things.

What I imagine should happen is what Canon says: the on camera turns off and just fires the slave whilst the slave does all the work. What happens is that the master still pops a flash. However, it still gives a reduced flash because in test shots there is a bias to the side with the lighting.

Will report back later.

Martin

[daveh]

martcol wrote:
What I imagine should happen is what Canon says: the on camera turns off and just fires the slave whilst the slave does all the work.

Yes but since the communication system is optical, you're still going to see the main flash sending a signal to the slaves. However, this should be just before the shutter opens and shouldn't affect your exposure.

[robertwgross]

When you see the Master flash fire, maybe that is the pre-flash only (for metering purposes) and there is no main flash firing, because that is your intent.

Most of us can't tell the difference between a pre-flash and a main flash firing since they are so quick and so close together in the normal case.

---Bob Gross---

[scottbergerphoto]

leony wrote:
Actually, there is a custom function on 550EX that lets you set the flash to TTL mode, instead of E-TTL. But all digital cameras only work with flash in E-TTL mode, so you're out of luck. I use mine when shooting in a studio turned down to lowest power in manual - to only get one flash - which trips the light slave on the studio strobes.

~ Leon.
I think you are only referring to dedicated flash, correct?
I use studio flash and manual exposure with my G2 and 10D using a flash meter. I don't believe that this is any kind of E-TTL. I also use non-Canon flash ( Quantum Q Flash T2D) in Auto Mode (flash controls the exposure). This isn' t E-TTL either although this flash can be used E-TTL with the E-TTL module.

[daveh]

scottbergerphoto wrote:
I think you are only referring to dedicated flash, correct?.

I think what he meant was that those cameras don't do (non E) TTL. (ie not TTL or A-TTL) This makes sense in the context that you can set the 550 to TTL, but your camera won't like it.

[scottbergerphoto]

daveh wrote:
scottbergerphoto wrote:
I think you are only referring to dedicated flash, correct?.

I think what he meant was that those cameras don't do (non E) TTL. (ie not TTL or A-TTL) This makes sense in the context that you can set the 550 to TTL, but your camera won't like it.

I use non canon flash all the time with my 10D and G2 with no problem. You can set the flash to "Auto" and let it judge the flash output via its own thyristor or set the output manually and use a flash meter. Quantum allows you to shoot E-TTL with a Canon module. All E-TTL and Nikon's Multi sensor Matrix Balanced Fill Flash are doing is trying to match flash to the background. You can do this yourself with Flash Exposure Compensation. I don't have the 550EX, but if allows you to set it to TTL it shouldn't be a problem using it. My film camera is a Nikon F5. I use an SB80DX flash in TTL (not Matrix Balanced Fill Flash-Nikon's version of E-TTL) and use flash exposure compensation to balance against the ambient light. The camera doesn't care what you do as long as your'e not in a Programed Mode. I always use Manual, Av, or Tv.

[daveh]

scottbergerphoto wrote:
I use non canon flash all the time with my 10D and G2 with no problem.

That's fine.

scottbergerphoto wrote:
I don't have the 550EX, but if allows you to set it to TTL it shouldn't be a problem using it.

But that isn't. Digital EOS cameras don't do TTL. They do E-TTL only.

[martcol]

So here goes, I had a go and checked every setting: Power on (obviously) with both flashes. 420EX set to “slave” and 550EX “master” on the Wireless selector.

420 shows Group A and Channel 1 but, I don’t think that’s relevant here anyway.

Using ETTL mode set on 550EX. No FE, No Bracketing and Ratio off.

Using the Sel/Set button I turn the flash off and use Sel/set button to come out of it. The little “Z” symbol flashes on and off as it’s supposed to indicating the flash is off.

I took shots with the Master slave off and on and there is a difference in the flash output because the shot with the Master flash off is lit more from the side (slave). I’m beginning to conclude that the Master flash doesn’t fire a full flash but fires a tiny flash because it just can’t help itself! It confuses me because the manual states it will turn off. That also seems to be what Canon support says it will do.

What do you think?

Martin

BTW - it doesn't seem to be a pre-flash for metering. If the intention is to turn off the on-cameral flash, why would it use that to meter? What would really help settle it for me is if some kind soul who owns a 550 and 420 had a go for me and see if it's the same?

[kidego32]

Martcol,

I have the exact same setup, and have run numerous tests, and my results are a carbon copy of yours.

At first I was baffled as to why the 550 still fired, but like you, I noticed that the lighting in the picture changed when the 550 was either on or off.

I wouldn't put too much faith in what canon says, as it appears to me that they're just quoting what's in the instruction manual. I doubt the person that emailed you actually tested the scenario.

As a further test, you can try turning off the 550, taking a picture, then actually covering the flash head, and taking the picture again, and compare. This should tell you if the flash that you (and I) are seeing is actually flash or just some sort of required communication between the 550 and 420.

In my opinion, I'm pretty sure that the flashes are working properly.

Best regards.

[daveh]

martcol wrote:
I’m beginning to conclude that the Master flash doesn’t fire a full flash but fires a tiny flash because it just can’t help itself! It confuses me because the manual states it will turn off.

"Off" means it won't fire during the exposure. However, the flash is still used to communicate before the exposure.

[daveh]

Here are some quotes from the manual that I think will help explain: (All typos are mine of course.)

"The Master unit's wireless signal is transmitted to the slave unit(s) at almost the same time as the preflash."

"The master unit's flash head zoom setting is automatically set to M 24mm. This gives the wireless signal the maximum coverage of 80 degrees. You can also press the ZOOM button to change the zoom setting manually. However, this will narrow the wireless signal's coverage. "

"Do not place any objects between the master unit and the slave unit(s) which may obstruct the wireless transmission. "

"Use the bounce feature to turn the body of the slave unit so that the sensor is exposed to the master unit."

"For an indoor setup, the positioning can be less precise since the wireless signals can bounce of the walls."

Under Specs: "Wireless functions: Transmission System: Optical Pulse Transmission. Transmission Angle: Horizontal approx 80 degrees, Vertical approx 60 degrees (At M 24mm zoom setting.) (Manual zooming of flash head also enabled.)"

In addition, there are various drawings showing the wireless signal as a cone emanating from the flash head.

So, reading between the lines, I assert that: the master sends instructions to the slave(s) by encoding the information on a flash that occurs just before the shutter opens.

Another quote from the manual: "Even if master flash OFF is set, the master unit still transmits the wireless signal to the slave units." Or as Canon said in their response to you "it should not fire a flash and simply trigger the slave unit" which is true but just remember that the "trigger" is an optical pulse emanating from the flash head. You'll be forgiven for thinking that such a" trigger" looks a lot like a "flash" :) But really it's OK because the shutter hasn't opened yet.

[martcol]

Thanks so much for all your help!

I get really paranoid about all this kit! Kidego, just knowing that yours is the same helps! And like you, I'm less worried because the effect is still there.

Daveh, I really appreciated the trouble you went to! As I'm reading your post, I can almost recite it by memory as I have read my manuals over and over! What threw me is that I thought that the information would all have been communicated via the infrared device. Hence, I immediately expected absoulutely no flash. I still think that is the impression given in the manual.

Anyway, I'll stop worrying about it now :D

Thanks again

Martin