What’s a Prime Lens and Why You Need One

Prime lenses are lenses that use a single fixed focal length, as opposed to zoom lenses which offer a range of variable focal lengths. It’s simple, really; zooms can zoom in or out, primes cannot. While this would seemingly limit the effectiveness of primes compared to zooms, there’s more to the story.

Due to the nature of optics, prime lenses are intrinsically less complicated than zooms. While a zoom lens might need a myriad of elements, groups, and moving parts, prime lenses are uniquely optimized for maximum performance at a single focal length. When compared to zoom lenses, prime lenses nearly always offer superior image quality, lighter weight, smaller size, lower cost, and vastly better low-light performance.

Now that you’re up to speed, let’s dig into all the ways prime lenses are best.

Prime lenses are constructed for performance

I’ve briefly covered the most prominent reason to buy a prime, better image quality, but let’s get into it a bit deeper.

Distortion, chromatic aberration, diffraction; these are all optical aberrations that photographers really hate. They cloud the image, distract from the end product, and make otherwise good photos ugly. They’re also, coincidentally, exacerbated by an increase in the number of lens elements through which light must pass.

Zoom lenses are packed with many more elements than your typical prime, including moving elements that further complicate things. As light passes through these elements it becomes degraded and distorted, introducing the previously mentioned and unwanted optical aberrations. To correct for this, optical engineers introduce even more glass in the form of corrective elements. The end result is a massively complicated assemblage of glass that produces nothing more than a decent image.

Prime lenses, on the other hand, are extremely precise. Designing for a single focal length allows the designers to create a lens that’s completely tuned to produce optimum sharpness, contrast, and performance with no compromise to image quality.

Another area in which primes trump their zooming counterparts is in the production of acceptable bokeh. With zoom lenses, unless you have an unlimited budget, it’s pretty difficult to generate that luscious blur we all covet. By contrast, even the least expensive prime lenses can produce gorgeous blur and amazing subject isolation.

The bottom line? For shooters obsessed with bokeh, sharpness, and superb optical fidelity, there’s nothing better than a prime lens.

Primes can improve your photography

Shooting primes will make you a better photographer. And while this is the least quantifiable reason to shoot primes, it’s the reason that will have the most lingering impact on the photographer.

From learning how to zone focus and manual focus, to better understanding aperture, primes are stimulating in a way that zooms never seem to be. You’ll hunt for the perfect shot, the perfect angle, and the perfect composition. You’ll zoom in and out with your feet, and experience not only the camera and lens, but also the environment in which the photos are taken.

With zoom lenses, there’s a potential to become lazy. Take this hypothetical situation; you’re using a massive zoom lens while out in the city for some architectural and street shooting. You spy a bridge some hundreds of yards in the distance. Deciding it would make a great picture, you zoom in and snap! Job done, photo taken. Time to get a coffee and go home.

But let’s imagine you were to catch a glimpse of the same bridge while using a 35mm prime lens. If you want the shot, you’ll have to take a walk. On the way, you might see a man with a toothless smile fishing in the river. You might see a beautiful couple strolling through fallen leaves. You might see a particularly photogenic cat, strolling in a particularly photogenic way, with a particularly photogenic snack hanging from his lips.

When you get to the bridge, you might stumble upon a more interesting perspective, a shot you never saw from the former great distance, or an architectural detail you’d like to highlight. You may find a perspective from underneath the bridge that creates an image that you’ve never seen before. You may even find a crumpled up twenty-dollar bill.

The point is, when you’ve got to move your feet to get your shot, you never know what you might find.

It should also be said that you might find nothing at all. But at least you’ve burned a few calories.

This shot was made with an Olympus 28mm Zuiko prime.

Specific primes are built to make a specific shot

Swiss Army knives are pretty analogous to zoom lenses. They’re decent at lots of tasks, but exceptional at none. And in the same way that a Swiss Army knife isn’t the best screwdriver, corkscrew, or nail file, a zoom lens is never going to be the best landscape, portrait, or street photography lens.

Prime lenses, on the other hand, are purpose-built for a specific task. They give the shooter the focal length that perfectly complements their type of shooting. So whether you’re shooting street shots and need big, fast apertures; headshots and need superb subject isolation; or macro shots and need impeccable clarity, there’s a prime that’s purpose-built for you.

The bokeh in shot could only be achieved with a prime lens.

This is exemplified in no more obvious scenario than in street photography, where shooters often rely on available light and demand a specific perspective to create their vision. Finding a lens that offers the perfect pairing of focal length to suit your style with a maximum aperture that’s fast enough to capture images by the light of the streetlamps is a lot easier and affordable with primes. With zoom lenses, often the apertures just aren’t fast enough. The result is a reliance on high ISO (noisy, ugly shots), or introduction of rampant camera shake. Yuck.

Furthermore, many street shooters want to be right up in the action. This closeness imbues in their images a sense of place and purpose. The viewer feels more in touch with the scene, more involved with the image. It’s difficult to do this with a big, honkin’ zoom.

Primes are small and light

Due to their concise design and construction, primes are much lighter than their zooming pals. In shooting environments where carrying a lot of gear just isn’t practical, it’s best to carry one or two prime lenses. Due to the tiny footprint of most primes, it’s actually possible to fit these things in your pant or jacket pocket. Try doing that with a zoom lens and you’re likely to incur suspicious stares from strangers.

There’s nothing like the simplicity of using just a single, tiny lens to make amazing images. And the fixed focal length often spurs surprising bursts of creativity. For adventurers, street shooters, travelers, or anyone who values compactness, primes are the perfect fit.

Primes are cheap (sometimes)

For the most part, prime lenses of serious quality are much less costly than zoom lenses of comparable quality. Especially when shooting legacy glass, for instance, it’s possible to buy a full suite of specialized, dedicated primes for the cost of a single high-spec zoom lens.

If you want amazing lenses on a budget, primes are really the only way to go. It’s a simple job to get a wide, standard, and tele lens all for under $250. That’s pretty remarkable, especially considering that these were pro-spec lenses in their day, and even today they’ll give you much better images than your modern kit lens. Choose your brand, buy an adapter, and have fun collecting.

Zooms lenses have their place, but for many photographers primes are a better choice.

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