Portrait basics

D

epth of field is one of the most creative controls we photographers have. By choosing what’s sharp and what’s soft, we can draw attention to the important parts of a scene while de-emphasising everything else.

When we focus on a point in a scene, there will be an area in front and behind the point that also appears sharp. This area is the depth of field – and the great thing is, it can be expanded or contracted. Say, for example, that you photograph a person stood in a forest. Depending on your camera and lens settings, you could choose to record detail in the trees in front and behind the person, or instead transform the trees into an attractive blur. There are several factors that give us control over depth of field. First and foremost is the aperture (an adjustable opening in the lens that lets in the light). Its size is measured in f-numbers: the higher the f-number, the narrower the opening.

There’s a direct relationship between aperture and depth of field: narrow apertures like f/22 will give greater depth of field, while wide apertures such as f/2.8 will create a shallow depth of field. It’s a basic rule of photography: the wider the aperture, the less depth of field.

“By choosing what’s sharp, we can draw attention to the important parts of a scene while de-emphasising everything else”

So what does this mean for portraits? The classic portrait look is a sharp subject against a soft, attractively blurred background. So we’d usually choose a wide aperture like f/2.8 or f/4 to melt away all the distracting background detail and focus attention on the subject.

Of course, there are certain types of portrait where we’d want more depth of field. If, for example, we’re shooting an environmental portrait (see page 50), we’d want to record the detail in the surroundings, so we might use f/8. And if we’re shooting a group of people, we might need to account for those faces closer or further away from the point of focus, so f/11 might be a better choice. The second factor that affects depth of field is the distance of the subject from the camera. If the point that we’re focusing on is close to the camera, for example in a macro shot, then the depth of field will be very shallow. If the point of focus is far away, then the depth of field will be

Above A shallow depth of field is often the best choice for portraits. It focuses attention on the subject and hides distracting background detail.

Above At a wide aperture of f2.8, there is a shallow depth of field, extending roughly from the front eye to the nose. From there on, everything falls off into soft, attractive background blur.