1 more wireless ettl question??

To make this a simple question i will get to the point.
I'm going to be using a 580EX master on camera and a 430ex SLAVE off camera. I will be using the ratio system in the 580EX menue most of the time so do I have to put the the 580EX (master on camera) and the 430EX slave the same distance from the subject for the ratio system to work..?? If not, how does the slave off camera know how far it is from the subject?? Or to make myself more clear how does it know the subjects distance?

Blessings

Nope, any distance is fine for both flashes. Both flashes do a preflash, then power output is calculated based on how much light reaches the camera and the ratio. Note that 1:8 ratio is more like a 3 stop ratio, not 8 stops as it might imply.

Thanks Tim that makes sense for sure..

The key to wireless ETTL on a 580 is that the zoom button does more than zoom - it controls a bunch of things. Between that, the little wheel, and the set button, it's pretty easy.

well, I do appreciate the info for sure, I will get the swing of it soon enough when I have time to play with it.. Thus far, I have only used the pocket wizard setup and manually set my output on each strobe so this will be a fun experience. I just get a kick out of doing and learning new things!

Since I havent used the wireless Ettl system yet I have one more nagging question? If I want to set the slave off camera to be the main sorce of light while keeping the camera master flash for fill how would you set that Ratio? If I choose 1:8 ratio how does the camera know which flash to make the main light? is there some setting that needs to be done to set the slave as the main in the ratio chain? sorry if this sounds like a stupid question..

The ratio is always set as A:B. And the master is always A. The slave can be set as A, B or C. So, if you want to use ratios, you need to set the slave as B. If you want it to be the main light, you woud set the ratio accordingly, such as 1:4 or 1:8 or whatever.

I appreciate your reply Pacace, I'm still a bit confused at how the camera knows which flash is the main light? say you pick the ratio 1:8, how does the camera know to apply the lesser output to the on camera master? I understand that the ratio system does this but would if I wanted the master on camera to be the main light? what would the ratio be set to then? I'm sure I'm making this more confusing then it really is..does it have something to do with the A or b settings?

Thanks

The ratio is A:B, the master is on A, the slave/main light on B, therefore 1:8 is 1 from the master and 8 from the main light. If you wanted it the other way around you'd use 8:1.

so what you are saying is that this is canons screwy logic for for saying that 1:8 ratio sets the output of the slave at 3 stops brighter or just more powerful? so, if the it was 8:1 the master on camera would be the brighter flash?

Hopefully I can put this to rest very soon.. hehehe .. Thanks guys! You know how it is when you have un-answered questions in your head it drives you crazy..

so the A flash corresponds with the first number in the ratio and the B flash the goes with the second number? I hope this is correct, so I can sleep..

Yes, everything you said in that post is correct

tim wrote:
Yes, everything you said in that post is correct

Thanks for taking the time to help me sleep.. LOL

Just to make sure Tim, you told me to use the 420EX and not the 430EX with my 580EX, but he intends to use the 430EX, is his setup still correct?

https://photography-on-the.net/forum/showthre​ad.php?t=143260

Thank you!

420EX and 430EX are pretty much the same thing when used as a slave.

Cant believe i just noticed i put 420EX in my thread, i had ment the 430EX as well.....is it still the same deal...it wont trigger the 580EX i would have to use the 580 to trigger the 430?