Text and Photos by Chuck Place
During my years as a photography instructor, I have seen many great location portraits produced by my students. Great expression, nice lighting—they should be beautiful portraits, except for one major problem. The foreground, subject and background are all sharp. The images are so busy that the subject is overwhelmed by the surrounding details. It’s difficult for the viewer to know whether the subject or the location is the most important part of the photograph.
I think of this as the point-and-shoot camera effect where everything is in sharp focus.
There are subjects where everything in the frame should be sharp, such as the portrait of a Victorian couple in front of a Victorian building below, but portraits usually benefit from a shallow depth of field. Depth of field is defined as the area in front of and behind the plane of focus that is acceptably sharp. Human vision can’t actually see shallow depth of field. It’s an optical effect.
Shallow depth of field, however, is one of the most powerful tools in photography for separating a subject from its background. By capturing a sharp subject and letting the background go soft, you are telling the viewer of your image what is most important and what is less important. It’s a relatively simply effect to achieve, but you must take control of your camera and get away from letting your camera make photo decisions for you.
First, set your camera to full Manual or at least Aperture Priority. The aperture, or f-stop, controls depth of field by changing the size of the opening in your lens. High f-stops numbers, like f16 or f22, create a tiny opening and lots of depth of field. A small f-stop number, f2.8 or f4, creates a large opening, or aperture, producing very shallow depth of field.
I know. It would be nice if big aperture numbers created big openings and small aperture numbers created small openings, but it’s the reverse. Blame the optical engineers. Maybe the easiest way to remember this is small f-stop, or aperture, numbers give you the least depth of field and higher numbers give the greatest depth of field. Once you start using this technique, it will quickly become second nature.
The lens aperture setting is not the only way to produce shallow depth of field in a photograph, however. The longer the focal length of a lens, the easier it is to get a sharp subject with a soft background as seem in the featured image of Deer Dancers above. A short telephoto has traditionally been the preferred portrait lens partly because of this ability to produce a soft background. A longer telephoto will produce an even softer background, making it easy to separate your subject from the background clutter. A wide angle lens, on the other hand, makes it difficult to soften your background.
One other technique for achieving shallow depth of field is moving the camera closer to your subject. It gets a little techie here. This is all about the relationship between camera to subject distance and camera to background distance. As you move the camera closer to your subject, the relative difference between subject distance and background distance becomes greater, producing a softer background. Check out this Depth Of Field Calculator, at http://www.dofmaster.com/dofjs.html, to see the effects of f-stop, focal length and subject distance on depth of field. Change the lens focal length and f-stop to see how depth of field changes.
If you are like me, all of this technical stuff gives you the shivers, but it’s all good to know. As a working professional, I tend to walk around with my lens aperture “wide open” or set for shallow depth of field. I shoot many subjects, from people to sports and even food, with a shallow depth of field. I need a reason to “stop down” my aperture and create great depth of field. When you have to tell a story with each image, shallow depth of field makes it easy to show viewers what is the most important subject in an image and what is secondary—usually the background. This approach keeps things simple and takes control of this powerful tool away from the camera. Your camera is, after all, just a computer with a lens hanging off it. The best camera is the one inside your head. Control depth of field and rule your world—photographically speaking.
For more on posing subjects for portraits, see our earlier post “Shy Photographer’s Guide To Putting People At Ease”.