Tricky Indoor Group Shoot (Advice?)

[Miresse]

Hello everyone, I'm looking for some thoughts on an upcoming shoot this weekend that has a couple challenges to overcome.

The shoot involves taking group-shots of a high-school mock-trial team at a courthouse. 17 teenagers should be fun to work with, but my main concern is the time/light restraints. I have maybe twenty minutes to take the shots they need in the courtroom, so I don't have the time to set up off-camera lighting. I'm going to be depending on the hallways skylights and natural lighting in the courtroom.

So between dealing with 17 teenagers, limited time, and limited light... I'm definitely open to advice.

The Camera: Canon Rebel XSi
The Lens: 24-70mm f/2.8L

There's also the added challenge that this is a governmental workplace, and even though the shoot is on a Saturday morning, I don't want to be a bother to anyone working there! I've been assured that photography is alright within certain limits, but I don't want to wear out my welcome.

-Thanks!

[CheaperKings]

Since I do not know what the lighting conditions are going to be in there, this is just mere advise. Take a tripod - you'll probably be shooting at pretty low shutter speeds.

[Jim Bryant]

try.....ISO 800 at f4 and 60th of second on a tripod. Shoot on manual setting and adjust you shutter speeds.

[autofocus]

I assume you have a speedlight?? You may want to consider bouncing off a back wall, especially if light colored. Work off your histogram, and adjust your flash output accordingly...depending on the distance, you'll probably have to bump it up

[Don34Tall]

Sounds like fun!- will you post the pictures here?