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If you are new to the digital SLR (dSLR) world, one of the things that you‘ll notice is that you have complete control over how the camera exposes the image sensor. Your exposure is the one critical element to SLR photography (digital or film) that will make or break your photo. There are other aspects, like sharpness, but exposure is the key. There is no “correct” exposure, because you can and will want to be creative with how much light, or lack of light, you want on your subject. Your photographs will stand out once you’ve mastered this crucial skill.

Exposure is a blend of shutter speed, aperture setting and sensor sensitivity (ISO). These three elements add up to the exposure value. In modern cameras, the camera has an exposure meter, usually within the viewfinder – on the side or bottom, that indicates “correct” exposure. But this is actually telling you that the camera is exposing for a mid-tone value that is relatively accurate to the light that’s being reflected off of a subject. Without getting too technical, this exposure reading won’t give you the precise color reproduction that you want. Nor will it give you the rich shadows and brilliant highlights, unless the lighting conditions are also ideal. And when does that happen?

The exposure value is a relative value that measures the amount of light coming through the lens in relation to the aperture setting, the shutter speed and ISO setting. What you are looking for is the exposure value that delivers the image that you want, illuminated the way you want without under- or overexposing the shadow and highlight details. Okay, so what exactly is under- and overexposure? It’s when there is excessive loss of image information within the highlights and shadows. In digital photography, once that information is “lost” you’re not getting it back. No matter how much tweaking you may try in Photoshop… as the over/underexposed segment of the photo is recorded as “zero” in the digital breakdown of the image.

So how do you avoid under- or over-exposure? By learning how the three components of exposure work together and how the built-in light meter works, you’ll be able to use exposure exactly how you want. It might be your kids’ faces or it might be a random stranger standing in the doorway of a bar under a neon light and you want them to be just out of silhouette.

Some quick tips: When shooting against a predominantly white background you’ll want to overexpose by maybe 1.5 stops if you want that white to be “white”, not dingy. This has to do with the 18% Gray concept, in which a camera exposure meter is calibrated to expose 18% gray perfectly, not pure white. Yet if you take a light reading, the white will “read” as “perfect.” Conversely, you’ll want to underexpose a black/dark background by maybe 1.5 stops to get the rich, velvety black background – with all the shadow detail – that you desire.