Using flash

Photography is often described as painting with light. Although some of the mystery has been removed now that dark laboratories full of strange chemicals are no longer needed, a lot of the traditional tools are still useful. Today's digital SLRs feature a range of light-metering options, but getting a proper, external light meter will still help you correctly expose a model when using external flash-heads.

There are two approaches here: The first is the standard method using professional full-sized flash units we describe below. The second is to simply buy a load of cheap flash heads off eBay and mess around. Because digital photography is so immediate, you won't waste film and you can check results instantly.

Even if you're going to experiment, it's worth reading this section to understand the principles behind using flash in a studio.

The meter in our example is a fairly sophisticated model, but you'll get by fine with a basic one. A light meter lets you set an ISO (film sensitivity) and shutter speed (length of exposure), and will then tell you what f-stop (amount of light) to let into the camera to correctly expose the area you've metered.

Don't freak out yet! This might sound like a fairly complex operation to the newcomer, but there are some basic rules to follow with flash photography in the world of fashion. A simple way to deal with this is to set your SLR to the lowest possible ISO. With the Nikon D70 we're using, this is ISO 200. If it's possible with your camera, use ISO 160 or 100.

By setting the ISO low, you're getting the best signal-to-noise ratio. Your photos will be as crisp and clean as your camera is capable of. However, these low ISOs need plenty of light to expose properly.

Next, set your shutter speed to 1/60th of a second. Now that your ISO and shutter speed are fixed, you can control the style of the photograph using the strength of the flash and measuring the required f-stop with your light meter. There are infinite ways to set up flashes around the model. Traditionally a three-point lighting system is used, but we've had good results with two, or nine.

Set your light meter to match your ISO (in our case 200) and shutter speed (in our case 1/60 second), then attach the light meter cable to your flash units. Now when you trigger the flash, your meter will tell you the correct f-stop for that exposure. You can then increase or decrease the intensity of your flashes to match the depth of field you want. Less light will give you a lower f-stop, and more light, a higher one.

Decide how much of the model you want to be in focus--for portraits it's often appealing to drop focus off quite early, so that the model's face is tightly focused on the eyes, then loses focus as the face retreats. This would mean an f-stop of something around f/2. If you're shooting full-length shots, you'll want to increase this to something around f/5.6 or 8.

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