G6 and SPeedlite 420 as Slave

Forgive my ignorance but I am very new to photography and am trying to learn on the fly. I'm having trouble using my speedlite as a slave with the G6. What settings should I be using on the camera and on the flash to make it fire. Also, can you disable the on-camera flash and just use the 420 as a slave. How ? Thanks in advance for any assistance to this newbie.

you need a master on the g6. the g6 by itself will not control the 420. or you can get a wein hotshoe slave, but then you can only shoot it in manual output mode

thanks. but isn't the G6 TTL compatible, therefore enabling it to fire the flash ?

TTL means "through the lens" which means it's capable of controlling all the parameters of the flash (with an eTTL-compatible flash) using the same metering sytems used to take the photo. it sends the info to the flash via the hot shoe, so if the flash isn't connected, the flash has no way to know when to fire. There's no infrared transmitter built into the G6 that sends that information. So to use a remote flash, you need either *another* flash with a built-in transmitter mounted to the shoe or the ST-E2 infrared transmitter that mounts on the hot shoe:
http://consumer.usa.ca​non.com …tegoryid=141&mo​delid=8304

Or you could consider one of these:
http://www.bhphotovide​o.com …ails&Q=&sku=367​068&is=REG
I can't find much about it, I can't even find it on Canon's site. I guess it fires in response to the on-camera flash going off, if anyone's seen a review of it, I'd be interested in finding out more. Metz makes a series of similar units, too. Might be cool, though it seems to me if I was trying to sidelight something, i wouldn't want my main flash going off...

Your question refers to firing the 420EX wirelessly as a slave. The internal flash of the G series or EOS DSLR's cannot function as a wireless master. You need to use a 550EX, 580EX, or STE2 as a master. A cheaper solution that maintains ETTL is to by an Off The Shoe Cord 2.

THanks a lot to all.