Photography is all about light. Without light, no matter how dim, you wouldn’t be able to make a photograph. However, that doesn’t mean that that’s all there is to photography. You need light, but to make a successful photo you also need to understand the qualities of light and how these affect your images.
The simplest of light’s qualities is its direction relative to your camera. There are essentially three directions: frontal, side and backlighting. The three directions have a different effect on how three-dimensional your subject appears to be due to the that shadows are cast. Let’s go through the three directions in order.
Frontal lighting is lighting that emanates either from behind the camera or from the camera itself. Built-in or on-camera flash is a frontal light. Frontal lighting has one big advantage. It evenly illuminates your subject so metering is fairly straightforward. However, it tends to flatten a subject. The shadows cast by frontal light are behind the subject, out of sight from the camera’s point of view. Shadows help to give a sense of shape and form to a subject. Without shadows a subject’s shape becomes more ambiguous. Shadows can also add drama to a photo. Frontal light lacks drama, making a photo look more like a record shot and be less interesting for this reason.
Side lighting is light that falls on a subject at roughly ninety degrees to the camera. This means that one side of a subject will be lit and the other side will be in shadow. In terms of helping to convey a subject’s shape and form this is ideal. Of the three directions, side lighting creates the strongest sense that a subject has three dimensions. There’s always a catch however. The catch in this instance is contrast. Side lighting doesn’t evenly illuminate your subject.
One side will be more strongly illuminated than the other (the contrast will be greater the harder the light is but the principle holds true even for softer light). One solution is to use a reflector or supplementary light to gently illuminate the shadow side (the key is to lighten the shadows without overpowering them).
Although this lamb is backlit there was enough ambient light to ensure that contrast wasn't too high. Note the attractive rim lighting around the back of the lamb.
Backlighting is caused when the light source is behind the subject shining towards the camera. If your subject obscures the light source - and if you expose for the background rather that your subject – the result will be a silhouette. Silhouettes look flat, almost like a cardboard cut-out. If the shape of your subject is strong this can be very effective.
Strong backlighting usually results in a silhouette. However, it’s less so when your subject’s shape is more ambiguous. If you don’t want to create a silhouette then you’ll need to also illuminate your subject. Flash is one of the easiest way to do this, a technique known as fill-in flash. The strength of the flash will determine the balance between the exposure for the background and your subject. Less is often more. Too much flash and you run the risk of losing the sense that there’s any backlighting at all.