Using Selective Focus-Shallow Depth of Field to Separate Your Subject from the Background
By: Marinda Van Zyl

Depth of field (DOF) is the distance in front of and beyond the subject that appears to be in focus. It is influenced by three factors:

• The smaller the aperture (higher f-stop like f16), the greater the depth of field. If the lens focal length and shooting distance stays the same, the depth of field is greater at f22 than f2.8.

• The shorter the focal length of the lens, the greater the depth of field. At the same aperture and shooting distance, a 28mm lens will render greater depth of field than a 50mm lens.

• The farther you’re away from your subject, the greater the depth of field. When photographing the same subject from 5m and 10m, the photo taken from 10m will have greater depth of field than the photo taken from 5m.

With greater depth of field, more of the photo is in focus, and with shallow depth of field, less of the photo is in focus. This exercise will show you how to make use of shallow depth of field which will allow you to blur the background, making your subject stand out from its surroundings and concealing distractions.

Find a repeating pattern in the form of a row of chairs, a fence, etc. Set your camera on a tripod, set it to aperture priority, and select the widest aperture (depending on your lens, it could be in the range of f2.8-f5.6). Focus on the first chair, and take a shot. Set your aperture on the next f-stop, take another shot, and do this through the full range of apertures your camera will allow, still focussing on the chair in front. Download the photos and compare them with one another. In the first photo you’ll notice that the front chair will be sharp while the rest of the chairs and the background will be out of focus. As you progress, more chairs will be in focus. Next time you’ve got your camera handy, practice focussing on different parts of a scene to see how depth of field influences focus. Practice when shooting the following:

• Portraits: focus on the person and blur the background, especially if there are distracting elements behind your subject.

• At the zoo: focus on one animal. The idea is to obscure the fact that the shot was taken at the zoo, to make it look like it was shot in its natural environment.

• Flowers: focus on one flower, or even a part of the flower, with the rest in the background…think sunflower fields. It creates a much more striking photo when you single out a flower instead of shooting the whole field.

• Musicians: focus on a part of the instrument.

• Babies: focus just on one hand or a foot.

• On the beach: focus on one seashell with the sea in the background.

You get the idea…have fun playing around!

Marinda Van Zyl is a South African photographer that specialises in weddings and fashion photography, but also shoots concerts, products, events etc. Visit http://www.marinda.co.za to view some of her work, as well as articles on photography and photoshop tutorials.