We’ve all heard of portrait lenses, right? And we maybe even know that lenses with a minimum focal length of approximately 70mm constitute these portrait lenses with popular portrait-specific focal lengths including 85mm, 105mm, 135mm and longer. But do we know exactly why these lenses are considered ideal for portraits? Here’s a look at the primary reasons why it’s usually best to choose medium telephoto lenses for portrait photography.
Portrait Lenses Make Faces Look Better
That’s quite a statement, but what exactly constitutes “better” in terms of a person’s face in a portrait? For one thing, it’s about the proportions of the features—such as nose, eyes, ears and mouth—in relation to the overall size and shape of the face and head. Assuming the photographer is positioned at a distance that renders the face a consistent same size in the viewfinder, a wide-angle lens is going to create a distorted appearance. It will exaggerate the nose in particular, as well as the eyes and mouth, and make them disproportionally large compared to the rest of the head and, if it’s visible in the frame, their body as well. Very few people look good like this; I’ve never met one. Great portrait photographers know that minimizing features in relation to the size of the head is a great way to make people appear more attractive in pictures.
It’s also generally more in line with the way we see and remember faces. A distorted exaggeration is unnatural in a way features viewed normally simply aren’t. So, a good rule of thumb is to use the longest lens possible in order to minimize the distortion of facial features. Space limitations—and needing to stand within speaking distance of the subject—generally limit that range to a maximum of about 200mm on a full-frame 35mm format camera.
Portrait Lenses Simplify The Background
With a wide-angle lens, a photographer has to stand very close to the subject in order to fill the frame with the face. With a telephoto lens, the photographer is free to stand much farther back and still fill the frame the same way. But the big difference between the two—aside from the proportions of the facial features outlined above—is how much background is evident in the frame. With a wide-angle lens, much more of the background becomes visible in the composition. This is sometimes preferable, particularly in journalistic settings where providing some context to the subject may be necessary. But in true portrait situations, all of that background is usually a distraction. Not only is it more in focus, which provides more competition for the center of attention, but it also shows more real estate. A telephoto lens, however, simplifies the background by condensing elements in the frame.
Look at the focal length range examples shown here. With the 24mm lens, the fire hydrant and ground are visible behind our portrait subject. But at the 170mm focal length, those elements now fall outside the frame and the greenery in the background provides a clean, simple, out of focus background from which the subject stands out. To be clear, this isn’t an effect of aperture; both of these photographs were shot at ƒ/2.8. But with the wide-angle lens, much more of the background is included in the frame—and it’s in reasonably sharp focus, which makes it more distracting. The telephoto lens makes the same background appear simplified. It’s this dual combination of selectively eliminating elements from the background and rendering it with the appearance of less sharpness that gives portrait lenses their good name.