Focusing in low light conditions

[bhphotography]

Your camera should have a focus assist built into the flash. Read up on the manuals about how to turn it on. I shoot Nikon so I'm not overly familiar with Canon's products. For me I have to put it on single servo focus, and on the center point. Focus assist has to be turned on on both the camera and the flash. Then the flash will use the red led lights in the front of the flash in a grid to give the camera the contrast it needs to focus

 

[Bluepoole]

I know what you mean...but just for the record, AI Servo is an auto focus mode, not a metering mode.

You're quite right...I was confusing myself there for a moment, thinking about all the different aspects all at once!