Trying to balance your flash with bright sunlight for an outdoor portrait scares the pants off people. It’s one of those things that seems so hard to do, especially if you are using off-camera flash without TTL. In that case, it’s all math and numbers and my head starts to hurt just thinking about it. Fortunately, it’s not really that difficult to do once you learn a few tricks.
The first thing you want to do is make sure that your camera and flash are both set to 1/3 increments. It should take 3 clicks to move your shutter speed a full stop, 3 clicks of the dial to move your aperture a full stop, 3 clicks to move your ISO a full stop and 3 clicks to move your flash power a full stop. If your camera isn’t already set up this way, odds are that you can change it in the menu settings (I know you can with Canon).
The second thing you need to do is work out a default setup for flash portraits. It’s simple … you need to have a basic setup for your camera and flash committed to memory. This will give you a starting point for any off-camera flash portrait. It’s easy to do, just set up your flash (with umbrella) in your living room with your camera on a tripod and a remote release. Then figure it out by trial and error, taking pictures of yourself (I have tons of pictures of me. Sometimes I just throw them on the bed and roll around in myself … but I digress). For example, I know that with my camera on ISO 800, flash at -8 power, f-stop 5.6 and the light about 4 steps (literally, walking steps) from the subject … I’ll get a properly exposed shot. That’s my starting point. I use this as my default setting when taking church formals. (When you are figuring your default setup, don’t do it outside. Do it indoors where your subject will be dark without the flash.)
Let’s be clear about this: There are some very precise formula’s for determining exposure. Many involve an incident light meter, tape measure, slide rule and Cray Super Computer. These methods are the purist way of determining the exact ratio of light for a portrait. I’m not a purist. I’m a wedding and portrait photographer who needs to be able to set up a shot in less than a minute so I tend to work a little fast and loose with the numbers. This is much easier to do if you know how to read your camera’s histogram and you have your camera’s LCD screen set to Highlight Alert (“The blinkies”).
Now that I have my default settings, let’s grab one of The World’s Most Photographed Children © and go outside.
Using my default settings I adjust my shutter speed to get the correct exposure. I like my backgrounds about 1 stop dark, so that’s what I expose for. As you probably guessed already, ISO 800 is way to high for an outdoor portrait.
Next I drop my ISO to 100 and adjust my shutter speed again. Here’s the part that’s important: I immediately reach over to my off-camera flash that’s sitting on a stand and change the output from -8 to o. I’ve changed my ISO 3 stops darker (800-400-200-100) so I need to make my flash 3 stops brighter to compensate (-8, -4, -2, 0). Now I am still at my default settings.
Before I go any further, I need to address sync-speed. My flash sync speed is 1/250 so I need to get to that speed (or lower). This is where the 3-click settings on your camera come in handy. I simply dial down the shutter speed 3 clicks to 1/250, then I dial up the aperture 3 clicks to 8.0. You can do this all day as long as you always use the same number of clicks each way.
Time to turn on the flash and take a shot:
That’s a pretty good exposure but it still seemed a little dull to me. It’s probably exactly right but I tend to overexpose the face a little when shooting outdoors because I just like the look. So, I asked my model to take two tiny steps closer to the light….
That’s it! I know it might sound hard when you read it on the page but if you just practice a little you will find that you can set up a portrait with off-camera lighting and ambient balance in about 30 seconds no matter where you are. Because you always start from the same place with your default setup, it’s just a matter of adding and subtracting “clicks.”