Focal length is how close you need to be to your subject to fill the frame. A simpler way to put it is how zoomed in you are. A smaller number means more zoomed out, a larger number more zoomed in. When it comes to lenses, there are a few categories of focal length.
Lenses in this range show more of the scene to your camera sensor. At the wider end the lens may cause what is called barrel distortion. The “fish-eye” effect is extreme barrel distortion. This happens because the field of view of the lens is wider than the sensor, so the image is “squeezed” in. Some lenses have countermeasures to minimize this distortion. Post processing can also reduce this effect. These lenses are most often used for event, landscape, astrophotography, real estate, and architectural photography.
Ultrawide angle astrophotography example.
At around 24mm, the barrel distortion becomes mostly unnoticeable. In this lower focal range, higher apertures are possible. This means images can be in focus at all points. These lenses are often used in real estate, architectural, landscape, astrophotography, and photojournalism. These lenses are wide enough to offer context and have an undistorted look.
Wide angle landscape example.
When you get to this range of focal lengths, the lenses become very versatile. This range is often used for portrait, lifestyle, weddings, and street photography, but can be used for almost anything.
Fun Fact: At around 50mm (often called the nifty fifty) the camera sees the world the same way you do minus peripheral vision.
Standard lens focal range example.
At this range, the lens’s perspective starts to separate the subject from the background. Images taken with these lenses have depth while still being zoomed in. These lenses are often used for portrait, wedding, and nature photography.
Tip: 85mm lenses are particularly popular for portraits.
Moderate telephoto nature photography example.
These lenses allow you to get right in the action from far away. At this focal length, perspective is flattened so the background will appear to be close to the subject (photos will look more 2D). These lenses are often used for portrait, sports, macro, wedding, and nature photography.
Variable focal length (zoom) lenses are the one size fits all of lenses. They work for many different types of photography. You don’t have to keep changing your lens, you just change the focal length to fit your needs. Your camera likely came with a zoom lens. Some common zoom lenses are 15-35mm, 24-70mm, 24-105mm, 70-200mm, and 70-300mm.
Fixed focal length (prime) lenses have only one focal length (no zooming in and out!). Some common prime lenses are 24mm, 35mm, 50mm, and 85mm.
Example of a prime lens.
When it’s time to purchase a new lens, there is much to consider. It is more expensive to get a zoom lens that can compete in image sharpness with a prime lens. Zoom lenses give speed and versatility to shoots and provide ease of use. Prime lenses perform better in low light and allow a shallower depth of field. You can do more with a zoom lens, but if you know exactly what you want to photograph, a prime lens might be the way to go. Choosing between the two depends on what you value.
You likely already have a zoom lens that came with your camera. If you’re ready for something better, which focal range should you buy it in? That depends. Kit lenses come in many different focal ranges. Just look at this list! That makes it hard to make a specific recommendation, but here are some important questions to ask yourself. Is your kit lens already all the focal range you want? Or do you want to extend your range? If you answered yes to the first question, replace your kit lens with a better lens in a similar range. If you want to extend your range, buy a very high focal length lens like a 70-300mm or a super low one like a 14-24mm. It really comes down to what you’re looking for.
The most popular prime lens is the 50mm f/1.8. It is often the first prime lens that people buy as it is easy to use, offers much more depth of field control than a zoom lens, is relatively cheap, and can be used in a wide variety of situations. It is a great lens for photographing moving subjects such as people because of the very wide aperture (f/1.8). Having a wide aperture allows more light to hit the camera sensor, which lets you have a faster shutter speed. A faster shutter speed gets those crisp, clean shots that everyone wants. A wide aperture also gives a much desired bokeh effect (clean transition from in-focus subject to a very out-of-focus background).
Not all lenses come with autofocus, and not all lenses are equally good at it. You’ll want to look for speed, accuracy, and sound. Your camera has an autofocus speed. If you have a fast camera, you’ll want a lens that can focus just as fast. You’ll also want an accurate autofocus. It doesn’t matter how fast your lens is if it misses focus. The last thing to look for is sound. You don’t want a loud autofocus, especially if you intend on using the lens for video. Check out reviews to see what other people are saying about the speed, accuracy, and sound of whatever lens you’re thinking about buying.
More on autofocus and possible problems.
Many mirrorless cameras have in-body image stabilization. This feature is less prominent in standard DSLRs. Getting a lens with image stabilization is important if your camera doesn’t already have it or you need extra stabilization. Why would you need image stabilization? When shooting at high focal lengths, image stabilization becomes necessary. Have you ever tried to keep binoculars from shaking? It’s difficult. The same thing happens with telephoto lenses. Without image stabilization, you’ll have blurry photos. Especially in lower light conditions where shutter speed is longer. Image stabilization is also necessary for any video work. No one wants shaky video. So, if you’re shooting at longer exposures, at high focal lengths, or taking any video, you’ll want image stabilization.
When looking for a lens, don’t forget about aperture. It’s usually written right next to the focal length and just as important. You’ll likely see something like 50mm f/1.8 or 24-70mm f/4. A lower number means better low light capabilities and more depth of field allowing you to get that much desired bokeh. These things may not be important based on the type of photography you’re interested in, but always keep aperture in mind.
This one is really a matter of you get what you pay for. In general, the more you pay for a lens, the sharper it will be. There are of course, differences in sharpness at any given price point. Prime lenses are usually sharper than zoom lenses (for the same price). Check reviews to see if the lens you are looking at will satisfy your desire for sharpness.
When looking for a new lens, you need to find a lens that will be compatible with your camera. Some places have a compatibility checking tool, but others don’t. Here is a table of different brands of camera and their respective lens mount.
Canon Full Frame DSLR EF
Canon Full Frame Mirrorless RF
Canon APS-C DSLR EF-S
Canon APS-C Mirrorless EF-M
Nikon Full Frame DSLR FX
Nikon Full Frame Mirrorless Z-Mount
Nikon APS-C DSLR DX
Nikon 1 Mirrorless 1-Mount
Sony DSLR A-Mount
Sony Full Frame Mirrorless FE
Sony APS-C Mirrorless E-Mount
All Cameras Micro Four Thirds
All Cameras Micro Four Thirds
Fujifilm X Series Mirrorless X-Mount
Leica Full Frame Mirrorless Leica SL
Leica APS-C Mirrorless Leica TL
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