Settings for Filler Flash?

I was wondering if you folks knew what settings I would need to use if I want filler flash for shots I'm going to be taking.

I will be taking photos of people in an outdoor setting and will want some filler flash regardless of the natural lighting conditions. I would usually keep it on ETTL, but I know then that if the camera feels it doesn't NEED the light, it won't use the flash, right? It's great that I've had this thing for years and am clueless as to how to use it. :borat:

I'll be using a Canon 550EX on a 10D and 20D.

On my Canon EOS 3 when i need to use the flash I keep it in auto mode, keep the flash turned on so when i push the shutter button the camera automatically takes a picture with the flash.

With the EOS 10D and 20D it should be the same unless you turned it off via a custom setting.

Everything you ever wanted to know about using flash with the Canon EOS system:
http://www.photonotes.org/articles/eos-flash/

The section on fill flash:
http://www.photonotes.org/articles/eos- ... #fillflash

Moose just showed you my BIBLE!!! :borat: