How To Balance Flash & Daylight

For those of you who participated in our poll, it's clear that you are interested in more "how-to" articles and one of the common questions we get asked is "How do I balance flash light and day light?"  To answer the question, let's deconstruct one of our images in which we balanced a sunset with off-camera fill flash.

In this image, we positioned our model high up on a grassy hill with the sunset behind her.  Definitely a challenging scenario for a camera set to Auto mode.  What you would get would be an image that was exposed for the sky and a model completely obscured by shadow.  If your camera has a built-in flash it would probably use it to fill the model but on-camera flash will produce very harsh shadows and potentially some red-eye.  The solution to lighting this scene is to balance an off-camera flash with the available daylight.

Learning how to deconstruct a photograph is a valuable tool for learning and there are two things that will make it easier.

1. Find the light source(s) by observing the shadows
2. Look into the reflections in the eyes to see the shooting setup

In this case, you can't see her eyes close enough but if you look carefully you'll see the tell-tale signs of a double shadow under her forearms and around her hands.  This tells us immediately that at least two light sources were used to light her.  And if you look REALLY closely you can see that one shadow is darker and harder than the other, which tells us that one strobe was set to a lower power than the other.

Ok enough guessing...here's how to balance flash & daylight for an image like this.  The first thing to do is determine the base exposure value for the scene.  In our case, we measure exposure by taking an ambient reading from our Sekonic L-758DR light meter. Set your camera to M mode and use this exposure setting to control the ambient light.  Now we can make our creative decisions.

We knew we wanted this scene to be bright and cheerful with a small difference between the fill light and sunlight.  The first creative decision you need to make when balancing light is "how much balance do I want to achieve?".  In this case we wanted a natural looking image that didn't look like we were using artificial light but we underexposed the ambient scene by 1 stop so that we could saturate the colors a bit more.

The next thing to do is determine your strobe exposure.  The placement, power output and diffusing of your lights will all help achieve a specific look.  We placed two AB800 strobes with standard parabolic reflectors on either sides of the model at about the same distance as the camera.  We then used our Sekonic L-758DR to trigger the strobes and take an exposure reading.  We lower the power output and take another reading until we achieve the same exposure value as the ambient light (eg: both ambient and strobes measure f8)  We then dropped the power settings of the left strobe so that the front of our model didn't appear flat.  If we had lit her completely evenly with two strobes there wouldn't be any depth to her clothes or body.  We used one more light directly behind the model to create a "rim" effect on her skin and hair. That light source is called the Sun!

Learning to balance strobe and ambient light is an extremely powerful technique that will elevate your photography to the next level.