Imaging: Flash dance

Take the time to get to know your flash a little better - your photos will thank you for it.

Not so long ago, the only two questions that people had about flashes were, "does this camera have one?", and "how do I switch it on and off?" Ahh, life was so much simpler back then. But we're all a bit more demanding these days, so this month I'll be looking at getting the best from your camera's flash unit.

PC World has touched on various aspects of flash photography in the past, so I've pulled together this guide with help from our resident experts. Depending on your camera model, you may need to check the manual for specific guidance, as there are no hard and fast standard instructions that will cover all models - though most cameras do stick to the same terminology and icons.

Understanding your flash

The key to using the flash is to understand its limitations. If the flash is too close, it'll bleach out the subject. Too far and you'll lose detail, and beyond 5-10 metres, most will have no effect. The reason that there are so many flash options is that they're designed to help you balance the lighting for different shooting conditions. So let's take a look at the basic modes.

Automatic flash

Most of the time, you can simply leave your camera's flash set to Auto. When set this way, the camera determines whether the flash needs to fire and sets the shutter speed accordingly. Confusingly, many cameras represent this auto mode by not displaying a flash icon. Some may show a lightning bolt with a capital A next to it.

Always fire

This option is just like the old days of turning the flash on. If you want a camera to flash regardless of the shooting conditions, then scroll through the flash options - there's usually a dedicated flash button for this task. On most cameras this "forced flash" is depicted by the lightning bolt icon.

Fill-in flash

Everyone knows a flash is essential when taking photos of people in dark conditions, but it can also be a lifesaver during the day. At times, the background can be much brighter than the foreground, causing people or other subjects to appear in shadow.

The solution here is to set the exposure from the background, but use the flash to illuminate the foreground subject. Since your flash has a range of just a few metres, it'll affect only the nearby subject, allowing both the foreground and background to be exposed correctly. This technique is called a fill-in flash and is invaluable during dusk, dawn or dim conditions. You can also use it in long night exposures if someone is standing a short distance from the lens - but ambient light can also work. Some cameras have a special shooting mode for fill-in flash (usually depicted by the outline of a person with the sun behind them), otherwise use the "Always fire" mode described above.

Red-eye reduction

Red-eye occurs when light from your flash is reflected by the eye's retina. When the scene is dark, your pupils open wide and this allows more light to reflect back to the camera. By flashing the subject several times prior to taking the picture, the red-eye reduction mode makes your subject's pupils close down to a smaller size, thus decreasing reflected light. When you use this mode, remember that it will take around a second longer for the picture to be taken, so don't pull the camera away as soon as you press the shutter release, or you'll blur the picture. Unfortunately, red-eye pre-flashes can also cause people to change expression or start moving before the actual picture is taken. Rather than using red-eye reduction, an alternative is to take two pictures close together - just be sure to warn your subjects that you're going to do it.

Low-power mode

Sometimes a flash can bleach out your subject because it's too bright and/or too close to your subject. This is where the low-power setting comes in handy, as it lets you control the output of the flash. Depending on the camera, you might be able to reduce its intensity by 50 per cent or more. You can use this mode when you need the flash to fill-in shadows, or when you're taking a close-up and a full burst of light would overexpose your subject.

Advanced settings

Now it's time to delve a little deeper into flash settings. Many of these terms have been in photography for decades, but used to be reserved for photographers who were willing to pay more for their camera than their car.

Slow sync

Slow sync is a handy option for night photography. Use it when you want a long exposure to capture background details, but you also want to fire the flash to freeze foreground action or illuminate a person in the image. This mode fires the flash and slows the shutter speed (hence the term "slow sync").

Second curtain

Many cameras give you the added choice of ordinary slow sync or something called "second curtain flash". I'm betting you have never heard of it before. It's not new, but until digital cameras appeared, it was rare to see this feature mentioned in consumer models. When the flash fires in normal slow sync mode, it fires right away, then leaves the shutter open for a while to expose more of the background (this is also called first curtain). In second curtain exposures, the shutter opens for a while, then the flash fires at the end, right before the shutter closes. This can create different effects but only start using this technique once you have mastered flash photography.


hotshoe external flash If you find the operation of one flash is confusing, many high-end cameras offer a spot for a second flash. This is frequently called a hotshoe or an accessory shoe. It's designed for mounting specialised flashes that can pump out more light, give the photographer greater range and more control over the scene's exposure. Hotshoe slots tend to appear on larger mid-range cameras.

Turn it off

Don't forget about the off switch. There are occasions when you absolutely, positively must make sure the flash doesn't fire - like in museums, art galleries and churches. That's when you should make sure that the lightning bolt with the "X" through it appears on your status display. Also, there may be times when taking a long exposure can capture more natural light and improve the shot. For this type of photography, you'll need a tripod, or a steady spot to rest the camera.

Click here to view a screen shot of a picture taken without a flash in a church. If flashless photography is permitted, look for interesting light.

Dave Johnson and Gordon Laing contributed to this column.

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