430EX II always fires?

[cusack]

Hi All

I have a question, I'm used to manual flashes but finally bought the 430EX II, so its a bit of a learning curve trying to understand that the hell the flash is doing and how it behaves in ETTL.

The question I have is ....is the flash supposed to fire with every single shot??
I have the flash set to ETTL and it will fire each time I take a shot with the 450D. This happens on all modes except for the no-flash mode.

I have pointed it on very bright scenes, yet it still fires. I'm under the impression that it should work like the pop-up flash (if the scene is too bright, it obviously doesn't need to fire). Is this normal? Or am I missing something really simple here?

Thanks

[krb]

This is how E-TTL works. It fires a "pre-flash" to meter the amount of flash needed then takes teh picture with that amount of flash. What you are seeing when shooting in bright light is probably just this pre-flash. That's my understanding, at any rate.

Also, there are many times that people want the flash to fire as fill light even if (or especially if) they are shooting under bright ambient light.

[cusack]

Thanks Ken, I think that pre-flash you're referring to is the red light that goes off before I take the shot. I'm ok with that.

I'm just wondering why it still fires even in bright scenes in ETTL. I thought ETTL was like "auto mode" so it should know that it doesnt need to fire?

[edit] What I'm referring to is the actual flash, not the pre-flash. :)

[rjc1]

My understanding is- the pre flash has to go off a split second before ,so the camera can measure the amount of flash that is needed in order to set the the correct flash amount to correctly expose the subject

( the red flash is the assist beam for focus assistance on a to dark subject)
that is my understanding and I could be wrong!

[putz]

I think that since you have it mounted on the camera and turned on it assumes that you know what you are doing... like wanting a fill flash!

[cusack]

I'm also checking because I bought this thing 2nd hand and not sure if it could be faulty.

ok thanks, so is that the answer? ....that it will ALWAYS fire when in ETTL mode?

[cusack]

I think that since you have it mounted on the camera and turned on it assumes that you know what you are doing... like wanting a fill flash!

ok I got you. Now I understand. It behaves just like the pop-up flash. If you pop it open, it will fire even if it doesnt need to simply because it's been opened.

Thanks everyone!

[alwaysonephotography]

Hold on, first of all you got way off track and ignored the first replier.

ETTL ALWAYS fires a pre-flash. Not the red plate on the front of the flash but the main flash. It all happens very fast. So fast, that even when the camera uses the flash it will fire TWICE. First the pre-flash and then the actual flash. This happens so fast that in most cases you actually see it as ONE flash but really it's two flashes.

The pre-flash is fired to light up the scene, then the camera looks at the scene and decides just how much power to give to the flash when the shutter opens so the image can be properly exposed. If it decides it needs any power then the flash will flash again while the shutter is open.

There are exceptions:
-You can prevent the flash from firing by setting a value in the custom functions (even though it is on)
-If the flash kicks into High Speed Sync mode (you must turn it on) then it will fire a pre-flash, plus many short flashes while the shutter curtains are open for proper exposure.
-It will also fire a pre-flash plus many flashes if you use it in strobe mode.

And also, a pop up flash acts the same exact way in ETTL (the only mode you can use it in). It will always fire a pre-flash and almost always fire a second flash for the exposure.

[putz]

that's my final answer, How else would you get it to fire a fill flash !

[apersson850]

It seems it's rather the repliers to this thread that got confused about the pre-flash.

It's like the OP have understood now, i.e. if the flash is there and on, it will fire. Unless you make a specific setting to not use it. That could be useful if you want the AF assist light (red light emitted from lens below main flash tube) but not the flash itself.