Lighting conditions vary drastically in our modern world. As you go about your daily life, you'll find yourself moving through bright daylight, office fluorescent, dimly lit rooms, complete darkness, etc. A flash on your camera allows you take well-exposed photographs in any lighting situation.

When to Use Direct Flash

In professional photography, direct flash is often only used as the last measure. In other words, for a professional to shoot with direct flash, the available light is atrocious, there are no walls or low ceilings to bounce light from, or it's just pitch black. In these tough cases, direct flash is a lifesaver.

But if you're using direct flash, be sure you're conscious of the shadows the flash casts. Since the flash unit is a small light source, its shadows will be quite harsh. You can minimize them by paying attention to your background. Photographing someone in front of a white wall will produce distracting shadows. But move your subject as little as six feet from the same wall and the shadows will be much less visible as the wall will darken.



Flash Fall-Off

The reason the shadows are reduced in the previous example is that your flash produces a perfect exposure on a flat plane that is similar to a lens's shallow depth of field. Flash exposure is completely based on distance. Objects closer than the flash's sweet spot will be overexposed and objects beyond the sweet spot will be underexposed. So as we move the wall further into the background in the previous example, it fades toward black.

The distance of your subject is important to consider as it takes more power to illuminate subjects that are further away. And a cluttered foreground can throw off even the most sophisticated flash system. Most flash systems read the light reflecting back from the scene, and close objects will reflect light back first. In such cases, the camera will end the flash cycle before the light reaches your subject.

For even exposure with flash, keep your subjects on a flat plane (that is, the same distance from the camera). The best direct flash photographs use this principle to great effect.

Power

Flash units come in various sizes and shapes. I recommend you buy the most powerful brand-name flash you can afford. Preferably one with a swiveling, rotating head.

You'll want the powerful flash because over distance, the light from your flash falls off. It takes more power to illuminate far off objects than it does close objects. More powerful flashes will give you more versatility and will also recycle faster, allowing you to take more photos quickly. More power also means you can use the flash with smaller apertures if necessary.

White Balance

Most flash units are balanced very closely to sunlight, but using your camera's flash white balance setting will put back in a little of the warmth that direct flash can take out of your photos.