580EX II External Flash Metering

Some interesting things that I am discovering about the 580EX II. It is the only SpeedLite that can be completely and truly controlled manually.

First let's address the confusing part:
The manual states that pressing <MODE> until <M> is displayed puts you in manual flash mode. In this mode you can adjust the flash output from 1/1 to 1/128. However 1/128 is hardly the lowest setting the flash will output. At 1/128 if your still blowing highlights at this point you will need to lower your ISO (assuming all else is where you need it).

So how to truly control the 580EX II output?

Custom function 5 set to 3 = External Flash Metering Manual
Here you can set the flash ISO to 1600 and it's f value to 1.0. Now the flash is as low as it will go no matter what. Set the flash's zoom manually for tweaking as well.

Feel free to correct me on anything.

Have you checked that with a flash meter?

From what I've read...

"External flash metering Manual" is what we used to refer to as traditional automatic flash. It means you need to manually set the aperture and ISO on the flash to match the camera. Then the flash unit's sensor is used to deliver the correct amount of light by measuring light reflecting off the subject.

It's completely different from manually adjusted flash power (1/1 down to 1/128).

If Picturecrazy doesn't respond to this thread, maybe send him a PM.

I don't think the OP is asking anything. I think he's giving us (or rather the 580EX II users) a tip on how to set the flash output to less than 1/128 power. Of course, I could be wrong.

tim wrote in post #3545503
Have you checked that with a flash meter?

No I have not. I don't own one

PacAce wrote in post #3546062
I don't think the OP is asking anything. I think he's giving us (or rather the 580EX II users) a tip on how to set the flash output to less than 1/128 power. Of course, I could be wrong.

Yes! Just trying to learn and be helpful. I was hoping someone could confirm my thinking.

This page describes this new function and clears up some of my thinking. Basically there is still automation occurring in the sense that the flash now "sees" the amount of reflected light and cuts off when it thinks it should. BUT you can change things to get less light output than the normal Manual mode, at least it seems that way in my testing.

http://www.usa.canon.c​om …tArticleAct&art​icleID=946