Balancing ambient light with another source

Mum

In this shot, I’ve combined the ambient light in the room with an external flash unit (Canon 580 EX II) that’s placed to the left of the scene.  The flash unit is lighting the subject (my Mum :) ), while the rest of the scene is lit by the ambient light, which is basically that lamp on the shelf, although there was another light on in the kitchen but it wasn’t really adding much light.

Now why would you want to do this, you may ask.  The problem is that the ambient light isn’t enough to light the scene evenly.  If you expose a scene like this so that the subject is correctly exposed, the settings will have to be so open that you will over expose the lamp on the shelf.  If you expose so that the lamp on the shelf is correctly exposed, the settings will be so closed that the subject will appear in darkness.

To overcome this, you introduce another light source that you have fine control over and then balance the exposure settings on your camera with the power settings on the light source to achieve the overall exposure you’re after.

As I’ve said, I used a Canon 580 EX II flash head as my controllable light source - the method for achieving the balance is as follows:

  1. Make sure the flash is off
  2. Take a reading that will expose the ambient light (in this case the lamp on the shelf at the back) put your camera into fully manual and set your camera to those settings.
  3. Then turn the flash on and take test shots, adjusting the power of the flash until you’re happy with the balance between ambient and flash.

Of course, you don’t need to use flash.  You can use any kind of light, as long as you have pretty good control over how much light it can put out.

In the image below, my other source was the sun, which was setting to the left of the scene and lit my brother up nicely.

Patrick

I don’t of course have control over the power of the sun, but it’s a legitimate source of light!  Use it any way you can :)

For lighting techniques like this, and much more besides, head over the Godfather of external flash lighting David Hobby’s Strobist.com site.