Zoom Lenses vs. Prime Lenses: What’s the Difference?
If you own a DSLR or mirrorless camera, there’s a good chance it came with a kit lens — an entry-level zoom lens that covers the most popular focal lengths, from a moderate wide angle to a moderate telephoto.
But if you want to get the most from your camera, you’ll probably need to move away from the kit lens at some point. It’s then that you’ll encounter the arguments in favor of prime lenses and/or zoom lenses.
But what exactly are they? And is one better than the other, or should you find room for both in your bag? Let’s take a look.
What Is a Prime Lens?
A prime lens is a lens with a fixed focal length. They tend to have fewer lens elements, so are often smaller and simpler to build.
However, because they are optimized for a single focal length they also tend to be of higher quality than a price-equivalent zoom, with corner-to-corner sharpness.
They also have a larger maximum aperture than zoom lenses, making them better for use in low light conditions as well as shooting with shallow depth of field to separate the subject from the background.
Prime lenses cover all of the main focal lengths that a skilled photographer might need. This ranges from ultra-wide (around 10mm), to “normal” with a field of view similar to that of the human eye (around 35-50mm at 35mm equivalent), to telephoto lenses of up to 500mm.
Many prime users will have a favorite focal length they shoot at most often. But if you want full coverage — for the ability to shoot architecture, street, and wildlife — you’ll need to carry more than one lens with you and swap them as you go.
What Is a Zoom Lens?
A zoom lens covers a range of focal lengths and are popular due to the convenience they offer. They’re more complex to design than a prime, requiring a lot of moving parts in order to achieve the different levels of magnification. (Each of the lens elements needs to physically move closer or further away from each other as it zooms.)
Generally speaking, more elements will indicate a superior zoom lens. However, since the lens cannot be optimized for any particular focal length, you’ll often find that it has a “sweet spot” where it performs best at a specific combination of length and aperture.
It’s not uncommon for sharpness to drop off a little, especially in the corners, at the extreme ends of the zoom length. Zoom lenses also tend to be larger than primes and have a smaller maximum aperture. The aperture is usually not fixed, either, so will get even smaller as you zoom in.
One feature that zooms do have that is often absent on primes is optical image stabilization (OIS or IS). This enables you to shoot handheld at slower shutter speeds without your images being affected by camera shake. This is an important feature at longer focal lengths.
When Should You Choose One Over the Other?
Based on the above descriptions, we could conclude that prime lenses are for quality and zooms are for convenience, and to an extent this is true.
The popularity of “superzoom cameras ” — single lenses that go from as wide as 18mm on a crop sensor to as long as 200mm or more — shows that while people want the image quality of an interchangeable lens camera, many prefer to not change lenses if it can be helped.
Zooms are also essential if you shoot in situations where you don’t have time to change lenses, such as for sports or in harsh environments where you don’t want to expose the sensor and other camera internals to the elements by removing the lens.
There are a few other specific factors that you need to consider.
Primes don’t always have a larger aperture than zoom lenses, although as we’ll see, zooms with larger apertures are considerably larger and more expensive to make (and therefore more expensive to purchase).
For consumer grade lenses, primes do have a larger maximum aperture, which makes them much better for low light photography .
For example, a common kit lens on Canon DSLRs is the Canon EF-S 18-55mm f/3.5-5.6. At 50mm the maximum aperture is f/5.6. That’s three and a third stops slower than Canon’s entry-level 50mm prime, the EF 50mm f/1.8. This equates to about ten times the light.
In real terms, this means that if you were shooting at a potentially noisy ISO 3200 with the zoom lens, you could take the exact same shot with the same shutter speed at a much cleaner ISO 400 if you used the prime. Or, instead of shooting at a 1/20th-second shutter speed with a zoom lens, the risk of camera shake would be much less if you instead shot with a 1/200th-second prime lens.
For low light shots, primes are far and away the better option.
Bokeh (Background Blur)
The other aspect of a larger aperture is the greater control it gives you with depth of field.
A wide aperture, such as f/2.8 or greater, gives you much shallower depth of field and a nice bokeh — the creamy, out-of-focus background contrasted against a tack-sharp subject.
You will get out of focus areas using a slower zoom lens, especially if it’s a very long zoom, but will produce nothing like the same effect that you could achieve with a fast prime.
Another consideration in the comparison between primes and zooms is how they affect your creativity.
For example, it’s often recommended that anyone who wants to improve their composition skills should shoot with a single prime lens. The limitations of doing so force you to think more carefully about how you frame your shots.
If you can fit the whole of the Eiffel Tower into your frame simply by zooming out then chances are you’ll end up taking the same shot that millions of others have already taken.
But if it won’t fit into the field of view offered by your prime lens, you can either “zoom with your feet” or look for a whole different angle to shoot from.
Price vs. Quality
While discussing zoom lenses so far, we’ve mostly only been referring to consumer level lenses.
Zooms are not always slower and lower quality, but if you want something that has a large aperture equivalent to that of a prime lens — all while being high quality and sharp at all focal lengths — you’ll need to pay for it.
A lens like the Nikon 17-55mm f/2.8 covers roughly the same focal lengths as a kit zoom, but has a maximum aperture closer to what you’d get from a prime. It costs around $1400. Other fast zooms at longer lengths can cost several thousands of dollars and are aimed squarely at pros.
How to Build Your Lens Collection
When you’re putting together your lens collection, you don’t necessarily need to stick to either primes or zooms. In fact, for many users that would be a bad idea.
You can use Lightroom — or any other image organization software that enables you to filter your photos based on EXIF data — to tell you which focal lengths you use most. If you shoot specific things, then you may want to tailor your lens collection to that.
For most general use, you’ll want as much range as possible from your lenses.
The classic three prime lens set has something wide, something normal, and something long. For example, one such set would be a 28mm lens, a 50mm lens, and an 85mm lens in full frame terms (around 18mm, 35mm and 55mm for crop sensors). It’s a good starting point and enables you to augment your collection as you need.
Most manufacturers will offer a basic two lens zoom set, consisting of the 18-55mm kit and something in the region of a 55-200mm with similar build and performance. These offer excellent coverage and there are usually mid-range options available for those who want better quality.
Again, you don’t need to stick with just primes or just zooms.
Ideally you won’t double up on focal lengths too much, but you could augment the two zoom set with a fast prime at your preferred length (such as a 35mm f/1.8). Or in the three prime setup you could replace the wide prime with a wide zoom (around 10-24mm on a crop sensor).
Zoom lenses tend to be a safer bet at very long lengths (and, to a lesser extent, at very very wide lengths). On the other hand, you can’t really go wrong with quality primes at normal and portrait lengths.
It Really Depends on Your Needs
The question of prime lenses versus zoom lenses does not come down to choosing one or the other. There are good reasons for using both.
A prime lens is (often) cheaper, smaller, better quality, and better in low light. They’re ideal for more creative use, portraits, and street photography. A zoom lens is more flexible, more convenient, and better for times when you need to grab a shot quickly. They’re especially good for shooting wildlife and landscapes.
Do you prefer primes or zooms, or do you use both? Which lenses do you have in your collection, and which would you like to add next? Let us know in the comments!
Image credits: Sony lenses via K?rlis Dambr?ns, Nikon primes via 55Laney69, Canon zooms via Alan Levine, Very long lens via Henry Burrows, Low light restaurant via Tim McLaren, Bokeh via Osamu Kaneko, Eiffel Tower crowd via Rous, Old camera and lenses via Jaroslav A. Polák, Bird via Jacob Spinks