Professional wedding and event photographer Ryan Brenizer has some advice to put you ahead of the competition when shooting speakers (the human kind) under poor lighting conditions:
…it always amazes me when I’m shooting with a scrum how few photojournalists use their flash in a way that produces good results. They almost always dead-on or bouncing 45 degrees up with a diffuser, but both produce very flat lighting.
Ryan suggests a simple turn of the flash head in order to change the location of the light source, and his photo of Bolivian President Evo Morales shown here is proof that this technique gives great results when executed correctly. For further explanation and more tips on getting the shot, read his article “How to shoot a speaker: Timing and lighting” at the Amazon.com Photography Blog.