How much flash for 25 people

I have an upcoming shoot of people, outside, tree shaded, 8Am so no sun problem. Would be 20 - 25 people, so 10-12 person, front and back line. Probably cannot, but small chance of placing them into Sun if that would help.
On a Canon 40D, Canon 17-55 2.8 lens, would a mounted 580EX ll with a 5" wide Rogue reflector give enough face lighting? Or would it take both my speedlights?

Thanks

The rogue would simply waste power in this circumstance. With a group that big outside its not going to increase coverage or softness and it costs power. You really need two lights to get the spread you need.

OK, I've never used my ST-E2 transmitter, but would I need it, and each Speedlight off camera?
Or can I make it work with one on cam and the other on a tripod?

Thanks

trailguy wrote in post #17294545
OK, I've never used my ST-E2 transmitter, but would I need it, and each Speedlight off camera?
Or can I make it work with one on cam and the other on a tripod?

Thanks

I'd be surprised if the st-e2 will work outside in these conditions. Give it a test run asap. But you would want a speedlight on each side of the camers so you get a wider spread with less falloff. That would mean having each on a stand. Its beginning to sound like your best bet would be the bare on camera single flash.

I have until Dec 3, so I'll try it both ways. The transmitter would need only to work 20--30 ft from the flashes. Is range what you see as a possible problem?

No, the problem is that infrared transmitters don't work well in bright conditions, i.e. outside.

I'd get an off-camera flash cord and put my flash on a lightstand behind me, as high as it can go and aimed towards the group, with the zoom setting on the flash set to 24mm.

https://photography-on-the.net …/showthread.php​?t=1079962

trailguy wrote in post #17294681
I have until Dec 3, so I'll try it both ways. The transmitter would need only to work 20--30 ft from the flashes. Is range what you see as a possible problem?

The ST-E2 needs darker conditions to work well. Outside where its bright its hard for the flashes to see the near infared light pulses. It also requires line of sight to be read by the flash, so its tough to deploy flashes beside or behind the plane of the camera unless you are in a place where the signal from the ST-E2 can bounce. For those 2 reasons I'm not hopeful that it will work for you here. Even using the stronger visible light pulse from a master like the 580exII is tough outside and that has the benefits of a swivel head. This is why most of us have abandoned the visible light master system for radio triggers.

Outdoor shade is perfect for your group. Unless the flash will be your primary light, you only need your one flash - no reflector (just wastes light outside) and no second flash. Use the sunlight for your main light and the flash for fill. The flash needs to be about 1/2 to 1 stop weaker than the sunlight - all it will do is fill deep shadows and put a catch light in the people's eyes.

I think it worked ok. I did have to pp brighten faces of the back group. lights on a stand about 15' on each side of camera, angled in and about 35' from the group. Nothing professional, but did the job for them Christmas Card.
Thanks for the advice.

http://trailguy.smugmu​g.com …AS-GROUP%2C-A%2C-DS-L.jpg

A little bit of shadow showing, but a decent picture. you certainly met their needs. That'll make a beautiful Christmas Card!

Can we see what the shots turned out like?