Lens choice for portraiture

FOCAL LENGTH

A lens that is approximately twice the focal length of the camera’s normal lens generally provides flattering perspective for portraits. For 35 mm cameras, this is a short telephoto lens with a focal length in the range of 85 mm to 135 mm. For a medium-format camera, the lens will have a focal length in the 150 mm to 250 mm range.

You may have a digital SLR camera (dSLR) that can use lenses made for 35 mm film cameras. The focal length of the lens must be multiplied by a factor to get the equivalent focal length for your camera. That factor depends on the camera's sensor size and how it compares with the size of an image frame on 35 mm film. There aren't many digital cameras that have full-35 mm frame sensors. Most are smaller - typically 1.5 times smaller. This means that an 85 mm lens will be roughly equivalent to a 127 mm lens if used on a typical digital camera - well within the range for a terrific portrait lens.

Not only does this focal length complement the subject’s appearance, particularly the face, it also permits you to shoot from several feet away and still fill the frame without crowding your portrait subject. (Click here for further information on using 35 mm lenses on dSLR cameras.)

WHAT ABOUT A NORMAL OR WIDE-ANGLE LENS?

Using the camera’s normal lens up close to the subject (filling the frame with the subject’s head and shoulders, or even closer) tends to distort facial features, making the subject’s nose appear larger and the ears smaller, an effect that becomes even further exaggerated if you switch to a wide-angle lens and fill the frame. Unless you want your subject to have the facial proportions of a mouse, don't use a wide-angle lens for close-ups. If you fill the frame, you will have to be quite near to your subject. In fact, he or she will undoubtedly feel that you are too close, encroaching on his or her space, and the resulting discomfort may show in the image.

For three-quarter or full-length portraiture, however, a normal lens can usually be used effectively. If your subject is in a setting that should be included in the picture (known as an environmental portrait because the subject’s surrounding environment is also photographed), a wide-angle lens (24 mm to 35 mm) can often be used, and sometimes is your only choice if your working space is limited.

CAN I USE A LONGER TELEPHOTO LENS?

Using a telephoto lens that has a focal length greater than twice the normal lens can produce very pleasing portraits, however the distance between photographer and subject must increase as the focal length of the lens increases. This might not only make communication more difficult, but with a very long lens, there is often insufficient space for the photographer to be far enough away to properly fill the frame with the subject, especially if the portrait is full-length.

Nonetheless, a very long lens can also be used to photograph fine portraits.

ZOOM LENSES

If you have a good zoom lens, it will likely produce good portraits when used at focal lengths in the range of 80 mm to 135 mm. However, since you know in advance that you need only one specific focal length for portrait work, it is generally to your advantage to use a prime (fixed focal length) lens.

A zoom lens that is inexpensive may not produce images at all settings as sharply as a prime lens does. Some zooms may not focus as easily as prime lenses. Generally, zoom lenses are slightly heavier than prime lenses and do not have as wide a maximum aperture. A high-quality zoom lens will render sharp images throughout its focal lengths and at different focus distances. The best do not require refocusing when focal length is changed.

There are situations, though, that give the advantage to a zoom lens. Weddings come to mind, where you may be called upon to shoot a close-up portrait of the bride within minutes of shooting a wide-angle image of the entire bridal party. In such cases, it is often more convenient and timely to employ a top quality zoom lens rather than having to switch back and forth between prime lenses.

APERTURE

Fast lenses that have fairly large maximum apertures (ƒ2.8 and larger) are usually chosen for portrait photography. Shooting with a wide aperture, produces shallow depth of field, particularly noticeable with a telephoto lens, permitting the photographer to throw a distracting background out of focus so the viewer’s eye is drawn immediately to the subject.