Beginner wireless question using 7D + 580EX II

I've had my 7D + 580EX II for a while but I just started messing around with wireless for the first time last night while doing some self-portraits. Setting everything up was a snap but I'm still confused about controlling the pop-up flash on the 7D.

I understand that it needs to be up so it can communicate with the 580 wirelessly but how do I adjust it so that my exposures aren't getting any light from the built-in flash? Is that what the A/B ratios are for? From what I've read, the flash will always fire when it's popped up, but it can be adjusted down to 1/1024 power (or somewhere close to this number) so it doesn't show up in my shots. I just couldn't figure out how to do that.

I'm glad you asked this because when someone told me the wireless you spoke of I thought it mean radio wireless. What you're describing sounds like optical "wireless." To me wireless means radio but that's just because of computers I guess.

Norkusa wrote in post #12239644
I've had my 7D + 580EX II for a while but I just started messing around with wireless for the first time last night while doing some self-portraits. Setting everything up was a snap but I'm still confused about controlling the pop-up flash on the 7D.

I understand that it needs to be up so it can communicate with the 580 wirelessly but how do I adjust it so that my exposures aren't getting any light from the built-in flash? Is that what the A/B ratios are for? From what I've read, the flash will always fire when it's popped up, but it can be adjusted down to 1/1024 power (or somewhere close to this number) so it doesn't show up in my shots. I just couldn't figure out how to do that.

There is no need to dial down the power of the built-in flash. That trick would only be used if your built-in flash is in manual mode and is being used to trigger a simple optical slave.

The Canon wireless system may be optical, but it is not simple. It uses coded pulses of light to communicate between the camera and the external flash. (sort of like fiber optics)

If you are using ETTL, the wireless menu has 4 options: (wireless manual flash has 5 options)

1) Disable
2) ratio between external and built-in flash
3) external flash only
4) external and built-in flash together

With option number 3) the built-in flash only fires a preflash and command signal. It won't add any additional light to the photo. If you are really close to the subject, or shooting into a mirror, you might see a little bit of light, but it almost nothing.

This youtube video explains how to set up your menu quite well: http://www.youtube.com​/watch?v=iKYDFHYZg3o

Thanks msowsun! For some reason I was choosing option #1 which totally disabled my 580. The answer is obvious now that you cleared it up for me.

I was also a bit disappointed when I realized that the Canon "WIRELESS" flash control on the 7D is actually an optical flash trigger.

A real "WIRELESS" trigger could be used outdoors in bright light.

Mine works outdoors in bright light. The range was actually quite surprising. The max distance I tried was about 20' and it was quite reliable at that distance.

I stand corrected. I was using an off-camera flash bracket and working without a nearby subject and shooting into the sun. When I placed a back-lit subject in the frame, the flash fired.

The flash had been firing without a principle subject in my frame when the sun was behind me and when it did not fire when shooting into the sun, I thought there was a problem.

Obviously, it needed the feedback from the subject to fire the flash in back-lit situations...

Wireless = without wire. Which Canon's system is.

That wireless = radio is an old misconception within the English language domain. Similar things happen in all languages, I suspect. If you say trådlöst in Swedish, our word for wireless, then today I'd suspect most people would first think about what otherwise often is referred to as Wi-Fi.

The power reduction to about 1/512 of full power is what happens automatically when you select to use the external flash only. If you are one meter from a bright wall, with f/1.4 and ISO 3200 (or something like that, don't remember the details), then the command flash is sufficient to illuminate the target by itself. You may also see it as reflections in people's eyes, for example.