Hello Bill,
At the risk of sounding like a rebel, I'll give you a brief description of how I've gotten into studio photography (really basic level for the time being) with my G6 and a couple of ancient flashes. I've totally bypassed the whole E-TTL issue here, because I don't want to second guess my own gear. This way I feel I'm in charge (sort of!)
The tools:
G6, M Mode
Canon 420EX flash
Vivitar 5600 flash, manual setting possible
Generic flash, one power output
Two optical slaves, one from Hama, one from Wein (regular types, fire on first flash)
Sekonic 308s light meter
umbrellas
The method:
Mount the 420EX on the G6, set the flash output level to its lowest setting.
Set up the two remotes : Vivitar as my main strobe, the generic as my secondary (background or hair light)
Meter the two remote strobes individually to get the ratio you want. The Vivitar I set to manual, and adjust as necessary; the generic, I move back and forth (light fall-off) until I get what I want - or stick some white tissue paper in front, to reduce output (really high-tech - works great!)
Fire the G6 and 420EX, which triggers the two remotes via optical slaves, and meter the outcome. I typically end up shooting for a combined meter reading of about F5.6 and 1/125 seconds - your settings will vary.
Important notes:
The 420EX will synchronize with the G-Series cameras at up to 1/640th sec, but you'll probably not be able to synchronize any non-Canon flashes faster than 1/250, so be sure you keep that in mind, or your remotes will not fire.
Also, you don't absolutely need a flash meter to get started, since you can preview the histogram to see if you're not blowing out the highlights. But to get reliable results, the meter is definitely a big advantage.
As mentioned above, firing the flash from the G6 is actually a good thing, because it provides fillin light. You'll need to adjust flash output to get the results you want. In many lighting configuration, there's a light right in line with the camera, anyway, so this is a good thing.
So to summarize - you'll need to master studio basics anyway, so you might as well control all aspects of your camera and light sources, and do everything manually. The Vivitar 283 is ideal for this kind of work, since you can control output from the flash itself, independently from the camera.
Hope this helps!
Christian
The 420ex can only sync up to 1/250.


