First of all, the focal length in photography has to do with the lens on your camera. What is focal length? It’s the optical property of a particular lens. The focal length is the distance between the very center of the lens and the sensor of the camera. This measurement is done in millimeters.
But that might still be a little confusing. If you’ve ever shopped around for camera lenses, you know they all have varying focal lenses. For example, a lens with a 50mm focal length. All this means is that there are 50 millimeters between the optical center of the lens and the camera sensor when the camera is focused to infinity. This may sound like a big number, but it’s really not.
When we say the optical center of the lens, you need to understand a bit about how camera lenses are made. Your lens is not a single piece of glass. It’s a combination of different lens elements that combine to focus light and minimize distortion. The exact point where all these rays of light meet to form a perfect image is at the optical center of the lens.
It’s also important to understand that focal length has nothing to do with your camera. This is only a term used to describe a lens. It doesn’t matter if you have a full-frame DSLR, a digital camera, or anything else. The focal length only talks about the lens.
How Different Focal Lengths Work
Every type of lens has a different focal length. This is because the focal length is an indication of the angle of view. In other words, the focal length determines just how much of a scene is going to be captured by your camera sensor.
Think of it like magnification. If you have an extremely long focal length, the angle of view is going to be narrower with a higher magnification. If the focal length is shorter, the angle will be wider with a lower magnification to give you a larger area that will be captured by your camera.
To make it perfectly clear, let’s set up an example. Say you’re on the edge of a cliff and you see someone standing on the other side of the valley. They’re waving at you but are so far away that you can’t really see them. If you have a camera with a 25mm focal length and you take a picture, you’ll see pretty much what your eyes can. You’ll have a blurry picture in the frame and a beautiful view of your surroundings.
Change the lens to something with a focal length of 200mm and take a picture, you’ll clearly see the person smiling, all the details of their face, and maybe a bit of the background blurred past their head. However, the focal length is too high and so it’s like looking through a paper towel tube. The person is clear but the landscape is gone.
If you want to capture a picture of the person in clear detail and some of the landscape around them, drop down to a focal length of between 85 and 100. Now you’ll see the person clearer than you can with your eyes and a bit of the background. You won’t get the whole scene, but you’ll have an awesome picture of the stranger.
This is just an example, but it properly details how focal length works. To get a better idea of the focal lengths offered by the different lens types, keep reading.
Prime Lens Focal Length
A prime lens offers a fixed focal length. Prime lenses are usually moderate in size and weight, easier to store, and equipped with a maximum aperture of between f/1.4 and f/2.8. A prime lens has only one focal length and it can’t be changed, usually 50mm. This is perfect for a wide variety of photography and is recommended for beginners.
Zoom Lens Focal Length
A zoom lens offers variable focal lengths. This is the whole point of a zoom lens, that the lens can move to change the focal length. These types of lenses are ideal for people who photograph a wide variety of different things, from portraits to landscapes. If you want one lens for all situations, a zoom lens is best.
The only issue with zoom lenses is that they tend to be heavy and bulky. But they’re great because by simply changing the focal length, it’s like you’re changing the lens itself. Zoom lenses come in all different formats. You can see the minimum and maximum focal lengths in the lens description. For example, 70mm to 85mm.
Telephoto Lens Focal Length
Telephoto lenses offer a greatly enhanced focal length when compared to ordinary zoom lenses. The average telephoto lens is between 70mm and 200mm. That is a pretty large range, which makes them ideal for nature and wildlife photography. Thanks to the massive focal length, you can easily take a close-up photograph of an animal at a distance without it looking fuzzy or distorted.
Telephoto lenses are great for bird watchers, they work excellent if you’re sitting in the stands at a baseball game, and you can even take striking everyday photos of your city by simply setting up on your balcony and zooming in on your subject from a great distance away.
Super Telephoto Lens Focal Length
The Super telephoto lens offers all the perks of an ordinary telephoto lens but at a dramatic increase in focal length. With a super telephoto lens, you can expect an increase in focal length of between 200mm and 600mm. These are for extreme photographers who won’t be anywhere near their subject while taking photos. Again, thanks to the heightened focal length, this type of lens is great for wildlife and sports photography.
Wide Angle Focal Length
A typical wide-angle lens will offer a focal length of roughly 10 to 24mm. These are the best lenses to use for landscape photography and for shooting the interiors of buildings. Wide-angle lenses are ideal for any situation where you find yourself restricted in space. Because they have a very low focal length, they barely zoom at all. This allows you to capture a wider panorama.
Think of the difference between a wide-angle lens and a zoom lens as being the difference between looking at something through a telescope and looking at something with your normal eyes. Because your eyes don’t zoom at all, you can see everything in front of you. This is what wide-angle lenses do, hence offering a very small focal length.
Standard Lens Focal Length
A standard lens is very similar to a prime lens. These usually have a fixed focal length, somewhere between 35mm and 50mm, and they try to mimic what humans see with their eyes. Standard lenses use large apertures to allow heaps of light into the camera sensor, making them ideal in dark situations because they absorb more light.
Standard lenses are also great for portrait photography because they offer the best bokeh effect in which the background is pleasingly out of focus. If you can’t use a flash and don’t have much available light, and if you’re not trying to zoom in on something, a standard lens is best.
Macro Lens Focal Length
The focal length of a macro lens is anywhere from 60mm to 200mm, but the lens works quite a bit differently than the others. A macro lens specializes in close-up photography and uses a special setup that allows for an incredible 1:1 reproduction. That means the ratio is life-sized, so whenever you take pictures of small subjects, they will look normal-sized. If you take a picture of a bumblebee with a macro lens that has a focal length of 85mm, the bumblebee will look life-sized in the picture.
As you can probably guess already, macro lenses are only useful for taking pictures of very small things like pieces of jewelry and small insects.
The good news about focal length is that it’s not something you need to think about a lot. So long as you keep in mind that the focal length is for determining the angle of view when taking pictures, you’ll never have to think about it again.
The main thing to remember is that the larger the focal length, the narrower the view. With a telescopic lens that has a massive focal length, your field of view is very narrow, allowing you to take pictures of things from an extreme distance with perfect clarity but not being able to take in much of the surroundings.
On the flip side, a lens with a very low focal length offers an expansive field of view. You might not be able to pick up the small details that are very far away, but you can get the whole scene jammed in the picture.
If this is all too complicated and you want something that works right in the middle, we highly recommend a prime lens with a focal length of 50mm, as this is the sweet spot.