430ex strobe setup question

[Herm99]

Can someone please clarify something for me? I just picked up my first speedlite, 430ex, and I have a softbox setup with wireless trigger. I'm trying to figure out what mode the flash is using when I use it as a strobe. I don't believe the speedlite is metering as it normally does when its on the camera body. When its on the trigger the red prefocus light does not flash and it appears to be shooting at very high power, maybe full power? I left the flash on ETTL mode when its in the trigger but I don't believe it is metering light. Can someone tell me what it is doing when it's mounted to a trigger/strobe setup?

Should I be switching the flash to manual mode when i'm using it as a strobe?

 

[Overread]

This will depends upon what Wireless remotes you are using, however based on what you've said I'm going to assume that they are not the dedicated pocket wizard wireless remotes which support ETTL metering.


As such when the flash is used off-camera it can't get the light data from the camera, so it has no idea about the power to output for the scene; as such you'll have to shift it into manual mode and vary the output power yourself to get the amount you require.

 

[TCampbell]

The strobe never meters the light -- your camera does.

Here's how E-TTL & E-TTL II works:

When you shoot, the flash actually fires twice. But it happens so rapidly that you probably only perceive it happening once. It fires a "pre-flash" before the camera shutter opens, and another flash when the camera shutter is open. It meters the scene a few times before taking the photo.

It actually meters the scene with no flash all using all the metering points available in the evaluative metering mode.
It then fires the flash at a reduced power level -- by default this is 1/32nd power, but you can change it. As it does this, it re-meters the scene.
It then compares each area of the scene when there was NO flash to the same areas WITH the flash to determine the difference in lighting. What it's trying to detect is areas that are highly reflective OR areas that don't change much at all (e.g. a lamp emitting it's own light). Lamps emitting their own light might have fooled flash systems in the past, but the E-TTL system is able to detect this and realize that it's false light. It's also able to locate areas that are HIGHLY reflective (e.g. if there was a mirror in your scene) which would also throw off the accuracy. Finally, it also takes into account what the camera reports as the focused distance for your subject and biases the exposure by the amount of power which "should" be necessary to illuminate a subject at that distance for proper exposure.

After all of this, it sets the flash to the amount of power which it wants for the real shot, the shutter opens, and the flash fires a 2nd time. Note that this whole process happens so quickly that if you didn't actually "know" the flash is firing twice and watch the flash carefully you probably would never notice you're getting a double flash.

All "metering" is done by the camera ("TTL" stands for "through the lens") and the camera communicates either through the hot shoe OR via a commander transmitting to slave flashes via IR.

You also can use it in manual mode.

VERY IMPORTANT: IF you are mixing studio strobes (non-ETTL lights) with your speedlites then you switch everything to manual mode. A slave will normally fire as soon as it sees any flash. Consequently it'll fire on the "pre-flash" (when the camera shutter isn't even open) and then E-TTL II system will evaluate the light, re-calibrate, and then fire the "real" shot with the shutter open (at which point the studio flashes have artificially boosted the speedlite power BUT won't have re-cycled fast enough to fire again for the "real" exposure.) You'll end up with these dull shots as though you weren't using flash at all. If you have any "manual" flashes, then all flashes should be set to fire on manual mode. There are some exceptions (some light slaves which know about E-TTL / i-TTL technology know to "NOT" fire when they see the pre-flash.)

 

[Big Mike]

Great reply Tim, well said.

Just to reinforce what has been said. If you use a basic radio trigger to fire your flash, it will have no 'extra' communication with the camera, just when to fire...therefore there is no automatic (TTL) metering and the flash will fire at full power in TTL mode.

This is why it's usually best to put the flash into manual mode, and then control the output by selecting the power (full, 1/2, 1/4, 1/8 etc.)

It is possible to have E-TTL metering with an off-camera flash, but you must have a 'Master' unit on-camera and the remote unit must be a compatible 'Slave'. The 430EX can only act as a slave. The Mater unit can be a Canon 550EX, 580EX or 600EX-RT.
Also, the very latest Canon DSLR cameras can act as a master with their built-in flash (Nikon has been doing that for years).

Yet another option would be to purchase high end radio triggers, that are compatible with Canon wireless E-TTL.

 

[Herm99]

Thanks everyone, that answers my question. For the record I do understand how ETTL works, I just wasn't sure if my generic triggers (cowboy studio) would relay ETTL info, but apparently not. So they fire at full power, that is all I really needed to know. Thanks again!

 

[o hey tyler]

Thanks everyone, that answers my question. For the record I do understand how ETTL works, I just wasn't sure if my generic triggers (cowboy studio) would relay ETTL info, but apparently not. So they fire at full power, that is all I really needed to know. Thanks again!

So since it fires at full power in ETTL, you are switching the flash to manual mode and adjusting it accordingly, right?

 

[Herm99]

Thanks everyone, that answers my question. For the record I do understand how ETTL works, I just wasn't sure if my generic triggers (cowboy studio) would relay ETTL info, but apparently not. So they fire at full power, that is all I really needed to know. Thanks again!

So since it fires at full power in ETTL, you are switching the flash to manual mode and adjusting it accordingly, right?

Yep, I sure am.