When I’m bored or am stuck inside and want to take pictures, I sometimes practice with still life shots with small objects around my apartment. This one is of an old electric fan. For this setup I used 2 hot shoe flashes: a Canon 550ex for the background lighting and a 580ex for the foreground. In the following picture you can see the 580ex in a Westcott Apollo softbox aimed at the fan and the 550ex on the couch aimed at some assorted glassware with a blue gel on it to produce some nice blue bokeh for the background. I used my Canon 5D mark II with a 85mm f/1.2 set at 1.2.
Once I have everything set up the way I want it, I shut off the lights and use a flashlight to get focus lock before setting the lens to manual focus. Then I turn on only my background flash and test with that until I get the exposure I want for the background.
The trick is to layer on the light sources one at a time making sure each one is exposed as you want it before adding more. Even though I’m only using two in this example, It helps you keep track when dealing with more complicated setups. So here’s what my background light looks like by itself:
Finally I add my foreground light and adjust it until I get the exposure I want:
You can apply this technique to portraits or any other kind of photography that uses artificial lighting to get better control of exposure to every aspect of your photo.