Balancing bright sun (ambient) and OC flash

What's the fastest way to balance bright sunlight (ambient) and flash (Quantum Trio in QTTL mode on a bracket) without blowing out the subject and/or creating harsh shadows. Say for example I have subjects in an outside wedding and the sun is hitting them from their left side, I would think I'd want to be on the opposite side facing the sun to fill in the shaded side. I'm not going to have a lot of time to take a seperate ambient reading to get the flash output correct. The Trio does have EC for the head....I'm just struggling with balancing ambient and this flash head in moments where I need to work quickly.

If you're using a small light source to fill shadows, not create them, then leave it on the hotshoe and let QTTL do the work.

Off-camera flash may fill the shadows from the sun, but it also creates its own shadows which will not look good.

Thanks!....Oh most definitely I'm leaving it on the hotshoe. I think I'm going to shoot mostly Tv...1/125 to eliminate motion blur and let the camera figure the aperture and the Trio's QTTL do the rest for fill. I was really hoping for a cloudy day.... At least it's partly cloudy!...the bridal party only has 8 people (counting the bride and groom) in it. Post formals is where I will use my deep octa & 400w elinchrom head.

Man, why shoot Tv mode at 1/125? Stick camera in manual mode, pick fastest ss like 1/250 for your 40d, heck even 1/320 should work unless onboard flash can't let camera do that. Pick your aperture based on DOF and shoot. Adjust FEC for flash power if using flash in eTTL mode.

bobbyz wrote in post #12768697
Man, why shoot Tv mode at 1/125? Stick camera in manual mode, pick fastest ss like 1/250 for your 40d, heck even 1/320 should work unless onboard flash can't let camera do that. Pick your aperture based on DOF and shoot. Adjust FEC for flash power if using flash in eTTL mode.

I think 1/250 is sync speed...and I usually do all manual (just not at an outside wedding on bright sunny days). I'm not crazy about letting the 40D determine anything. The Trio has what is call QTTL mode...basically works in the same manner as Canon's ETTL. In some ways I thinks it might be best to have either all clouds or none at all...that way there's no messing with settings during ceremony. I was at rehearsal lastnight at 6:30 and the sun is setting directly to the B&G's left as they stand at the alter, (which is in front of those doors with window missing)

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This is where abbreviations cause trouble. I thought the "OC flash" in your title meant "off-camera."

DD974 wrote in post #12768795
In some ways I thinks it might be best to have either all clouds or none at all...that way there's no messing with settings during ceremony.

We'd all love to have constant lighting conditions. Being able to deal with changing light is what separates the photographers from the people with cameras.

I've been known to use Tv mode in such situations. It rarely gives you perfect exposure but it gets you close enough that you can worry about other things. X-sync shutter speed (1/250 with the 40D) is where I would start. Just be sure to set your ISO such that your aperture will wind up in the right range, regardless of clouds. Also be sure to enable safety shift on your camera.