What Is a Portrait Lens?
Portrait lenses (or rather, lenses-that-are-often-used-for-portraits-but-can-be-used-for-lots-of-other-stuff-too) have two key features:
They have a normal or short telephoto focal length. They have a wide maximum aperture.
This means that most portrait lenses designed for full-frame cameras have a focal length of between about 50mm and 105mm, with a maximum aperture of somewhere between f/1.2 and f/2.8, or so. (The equivalent focal range for crop-sensor cameras is between around 35mm and 70mm, so there’s a lot of overlap.).
Some typical portrait lenses you’ll see recommended a lot are the Canon EF 50mm f/1.8 and the Nikon AF S 85mm f/1.8, though there are plenty of higher-end options that cost more than most cameras, like the Canon RF 85mm f/1.2L.
If you compare these specs to the entry-level zoom lenses that come bundled with cameras, you’ll notice that while they often have the right sort of focal length, their maximum aperture is much narrower. For example, the Canon EF-S 18-55mm f/4-5.6 is designed for crop sensor cameras so, at 55mm, its focal length is bang in the sweet spot for portraits. It’s the max aperture of f/5.6 that lets it down.
So, what does all this mean for shooting portraits?
Portrait Lenses Give You Blurry Backgrounds
Aperture is how you control the depth of field, or how much of your photo is in focus. The wider the aperture you use, the lower the depth of field. This is what gives you the classic portrait look of a sharp subject with a super-blurry, bokeh-filled background.
If you want to take these kinds of portraits, then yes, you will need to invest in some kind of portrait lens. Although smartphones try to fake the portrait look with additional sensors and machine learning, it’s not quite the same as doing it optically.
However, it’s important to note that this is just one style of portrait, albeit a popular one. Portraits are photos of people, not abstract studies of lens blur. Just having bokeh in the background doesn’t mean you’ve got a good shot, nor does the absence of it mean that you’re a bad photographer.
Portrait Lenses Don’t Distort Your Subject (Badly)
Lenses bend light in order to project it onto your camera’s sensor. The wider the angle of a lens, the more the light has to be bent to get captured. One side effect of this is optical distortion, which is why portraits of people, and especially close-ups, shot with wide-angle lenses can look so weird.
Lenses in the normal-to-short telephoto focal range, like most portrait lenses, tend to produce very little optical distortion. They use a simple and reliable optical design that manufacturers have mastered. What little distortion there is with the telephoto end of the range can actually flatter your subjects.
For what it’s worth, there are wide-angle lenses designed specifically to minimize distortion. However, they’re mostly used by moviemakers with large budgets and professional architecture photographers. For most portrait photographers, it’s simpler to use a longer focal length or work around optical distortion than to invest thousands of dollars in niche lenses.
Portrait Lenses Let You Shoot in Real-World Situations
One of the big benefits of portrait lenses is that they are really easy to use in a lot of real-world settings. You don’t need a tripod or a load of flashes to make the most of them.
With a 50mm or 85mm lens, you only have to stand six to ten feet away from someone to take a great photo. In theory, you can take stunning portraits with telephoto lenses since they can blur the background even more—it’s just that you need to stand too far away to direct or otherwise interact with your subject, and certainly can’t take photos in a normal-sized room.
The wide aperture also gives you a lot of flexibility with your camera settings. When it’s evening, or you’re in a badly lit room, you can open the aperture to its maximum, crank the ISO up, and still use a shutter speed fast enough to freeze your subject—no flash necessary. If it’s bright out, you can use a slightly narrower aperture or just a really fast shutter speed and the lowest ISO setting your camera supports.
This flexibility to shoot how you want, when you want, is as much the reason portrait lenses are so popular with photographers as their ability to blur backgrounds.
But Portrait Lenses Can Limit You, Too
Portrait lenses are great. Every photographer should consider picking up an entry-level 50mm f/1.8 lens just to have a flexible lens that they can use for street, travel, and other casual forms of photography. It’s useful for those times when you inevitably get roped into photographing family events, too.
But if you don’t have one, that doesn’t mean you can’t shoot portraits. In fact, just shooting blurry-background portraits is a pretty boring way to work. If that’s the only way you can think of to photograph someone, then you’re missing out on a lot of opportunities.
In particular, there are plenty of times when the background is as important as the subject. Environmental portraits that show the context of the image are often a lot more interesting. I prefer the photos I’m using in this section of the article to the more standard portraits I showed earlier.
So yes, a special portrait lens is nice to have and is necessary to shoot a certain style of portrait. But that’s not the only style of portrait you can shoot—and it shouldn’t be.
