Flash As An Outdoor Key Light

In the last post we discussed on-camera flash as fill light for outdoor portraits.

Now we are going to move the flash off-camera to a light stand and use it outdoors as a key (main) light.

Here’s the difference…

When the sun is the main (key) light source for our portrait, and our flash unit only adds light to lighten shadows and control contrast, that’s fill-flash.

As a key light the flash unit now becomes the main light source. The sun becomes a secondary light source. Usually this means setting up our portrait so the sun is to the side or behind our subject. The sun is now a hair light, accent, or background light used to add dimension to our portraits.

Why move the flash off-camera?

As the key light, I want the flash to be directional—not originating from the camera position. My goal is to mimic studio lighting, outdoors.

To move my flash off-camera I need a few extra pieces of equipment.

My outdoor flash setup includes a light stand, an umbrella stand adapter, a large white shoot-through umbrella, one speedlight, and either a cord or wireless trigger to fire the speedlight. (See photo.)

Stand and Umbrella Adapter With Speedlight

How about you come along with me as my virtual assistant on an outdoor portrait session?

Today we are going to photograph a couple to celebrate their engagement. We have chosen a small park that has lots of trees to lean on, benches to sit on, and even a pond to use as a backdrop.

It’s five in the afternoon; the sun is still relatively high in the cloudless sky making for very high contrast, harsh lighting.

What to do…?

We could hang out, tell jokes, and wait for that fabled golden light of sunset that we as photographers love. But that would mean knowing some jokes to tell, and then dealing with dime-sized mosquitoes that love to begin feasting on human flesh as the sun sets. Next idea…

We could position our couple with the sun light off to the side or behind them. That’s sounds like beautiful hair and accent light to me! Then I could have you, my trusty assistant, grab a big reflector and redirect some of that sunlight back into their faces. That will work, except, I usually work without an assistant (you’re virtual, remember?). So without a voice activated reflector holder, now what?

I’ve got it! I can still use the sun as my background-hair-accent light. But instead of a reflector-toting assistant, I’ll use my trusty light-stand-mounted flash unit to light my couple. This allows meet to shoot without an assistant, and I am not limited to posing my couple only in locations where I can redirect light with a reflector.

I like this idea; let’s set it up.

The first portrait has our couple peeking through the “V” of a tree trunk. The sun is behind them at camera left providing great hair light and accent light. Now to add my flash as a key light to light their faces…

I position my light stand at about 30 degrees camera right and raise the light stand so the flash is about 2-feet above the camera’s height.

I tilt the white shoot-through umbrella down aiming the center at my subjects’ faces. I have manually zoomed the flash to its widest angle to allow for maximum fill of the umbrella surface. I have also attached a wireless trigger to the flash with a transmitter mounted in my camera’s hot shoe. (You can trigger your flash with a PC cord as well.)

The flash is in manual mode. This allows me to keep my flash-to-ambient ratio consistent for each series of shots. With TTL flash a change in camera angle or zoom will alter the flash output. I don’t want my key light intensity to vary in a series of poses, and so manual flash is a must in my book.

So how do you determine the correct exposure?

Here’s one simple method to get a basic exposure. Put your camera in manual at a low ISO setting. Set the aperture at f/5.6, which should give us adequate depth of field for this shot. Take a few test shots varying your shutter speed until you get an exposure that records the sun’s highlights to your liking. (Be mindful of your camera’s maximum flash sync speed.)

Next, turn on your flash. Take a few more test shots varying the flash output until the key light looks right. (If you own a flash meter, use it to set your key light output.)

As you shoot you can adjust the brightness of the sun light with longer or shorter shutter speeds. You can adjust the look of your key light by changing the flash setting, or by moving your umbrella stand.

As you can see in Portrait One the sun is providing beautiful hair light, accent light, and background light. The key light is a single flash unit and shoot-through umbrella at camera right.

I used the same setup for  Portrait Three. For Portrait Two, I moved the key to camera left.

Flash As Key Light, Sun As Hair / Accent Light

Using flash outdoors as a key light allows for a lot of flexibility. To a great extent you can choose time and place for your portrait sessions, and light your images to your liking.

Give it a try!



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