Notice how the buildings don’t appear to converge towards the top. They would on a wide-angle lens due to perspective exaggeration.

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[1] Secondary principal point of lens  [2] Focal length  [3] Angle of view (measured diagonally)  [4] Focal plane (image sensor plane)

When you look straight ahead with your bare eyes, the field of view in focus is around 50° to 60°. Wide-angle lenses are any lens that gives a field of view wider than that. Ultra-wide-angle lenses are a special kind of wide-angle lens.

Telephoto lenses provide an angle of view that is much narrower than human vision. 70-200mm lenses provide the classic telephoto focal range.

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Focallength

Learn more about what you can do with a standard lens in: Standard Lens Techniques: Using the Point of View to Draw the Viewer In 50mm Portraits, My Style: Creating A Picture of a Memory

Depending on the scene and your intentions, you might not need to go ultra-wide to frame what you want to show perfectly.

Learn composition techniques that leverage on the characteristics of different lenses in: Professional Composition Techniques (3): Making Good Use of Lenses

Getting up close to birds and other wildlife requires a special type of telephoto lens: a super telephoto lens. You may want to combine it with an extender for even further reach.

When picking a lens, one of the first things you must decide on is the focal length or focal range that you want. This is because the focal length describes the angle of view, i.e., it tells how much of the scene in front of you the lens can capture.

Longer focal lengths correspond to higher magnification and vice-versa. Wide-angle lenses with short focal lengths have low magnification, which means you have to get physically close to an average-size subject to fill the frame. But that also means you can fit large subjects in the frame without having to shoot from a distance. Telephoto lenses with long focal lengths have high magnification, so you can fill the frame with subjects that are further away from the camera.

Due to physics, a lens with a shorter focal length has a wider angle of view, and one with a longer focal length has a narrower angle of view. And that’s how we came to use focal length to describe the angle of view of a lens!

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Focaldistance vsfocallength

At 16mm, we can capture the entire façade of the fire station as well as the road and the hedge in the foreground. As the focal length increases, details appear bigger in the frame while more of the foreground and the building is cropped out. 200mm gives us a good close-up of the building name and the crests below it.

A standard or “normal” lens gives a perspective that is very close to that of human vision. Most kit lenses are standard zoom lenses. The popular RF50mm f/1.8 STM “nifty fifty” lens is a standard lens on a full-frame camera, whereas the RF28mm f/2.8 STM is a slightly wider standard lens on an APS-C camera.

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FOV tofocallength

Focallength formula

Light entering the lens converges (crosses) on its way to the image sensor. This convergence point is known as the optical centre of the lens and has the sharpest focus. The focal length is the distance between this convergence point and the image sensor.

* Focal length in ( ): equivalent focal length when mounted on interchangeable-lens digital cameras with 35 mm full-frame sensors

Ultra-wide-angle lenses take in so much that they are perfect for capturing grand scenes and large objects that are right in front of you, especially in tight spaces where you cannot move further back.

The focal length also affects many other aspects of your image, such as perspective and depth of field. To find out more,  see 4 Lens Concepts to Revolutionise Your Photos.

With long focal lengths, foreground and background objects will often appear to be closer together in the final image. This effect is sometimes called “telephoto compression”, although it is not actually caused by the lens itself. What really happens is that when using a telephoto lens, you will need to be further away from your subjects. So, relative to the distance from the camera to the foreground and background subjects, they actually are closer together. Another way of saying this is that since both the foreground and background objects are at a considerable distance from the camera, their relative sizes in the final image will be closer to reality. When shooting with a wide-angle lens you normally need to get close to the foreground subject so that it is sufficiently large in the frame, which is why more distant objects look comparatively smaller. The difference in apparent perspective is actually a result of how far you are from your subject.

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Any focal length above 135mm full-frame equivalent is considered telephoto. However, 70 to 135mm (full-frame equivalent) is considered short or medium telephoto. These are popular for portrait and product photography due to their natural perspective and comfortable working distance for close-up shots.

You need a very long focal length to capture a detailed close-up picture of the moon without cropping. The image above was captured at 1600mm using an 800mm lens and a 2x extender.

We usually describe a lens by its focal length. What does it refer to and how does it affect your images? Find out in this article.

Lenses are classified as wide-angle, standard, or telephoto depending on their focal lengths. Ultra-wide-angle lenses are a subset of wide-angle lenses, whereas medium telephoto and super telephoto lenses are subsets of telephoto lenses.

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Ultra-wide-angle lenses exaggerate perspective so distances between objects look bigger. When combined with the wide field of view, it can bring out a sense of space.

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The “Focal length vs. angle of view” comparison illustrates this relationship for both 35 mm full frame and APS-C format cameras.

A longer focal length… - Captures less of the scene (= has a narrower angle of view) - Makes distant objects appear bigger (= has a higher magnification)

Also see: Why Is a Super Telephoto Lens Necessary for Sports Photography? What is the difference between a 200mm and 300mm telephoto lens?

Focal length, or focal length range in the case of zooms, will usually be the foremost consideration when choosing a lens for a specific photograph or type of photography. The focal length of a lens determines two characteristics that are very important to photographers: magnification and angle of view.

Let’s look at what happens when we shoot at different focal lengths from the same position. Note: For ease of illustration, the angles shown in this article are the horizontal angle of view.

Learn more about how to make the most of wide-angle lenses in: Exploring Wide Angle Lenses Part 1: Photo Effects of Wide-Angle Lenses 24mm Closeups: 3 Simple Exercises for Mastering Wide-Angle Perspective

The focal length of a lens is defined as the distance from its secondary principal point to its rear focal point when focus is set to infinity. The secondary principal point is one of six “cardinal points” that are used as points of reference in an optical lens (front and rear focal points, primary and secondary nodal points, and primary and secondary principal points). There’s no predefined location for the secondary principal point in a compound lens—it could be somewhere inside the lens barrel or at some point outside the barrel, depending on the design of the lens—so there’s no easy way to accurately measure the focal length of a lens yourself.

“Angle of view” describes how much of the scene in front of the camera will be captured by the camera’s sensor. In slightly more technical terms, it is the angular extent of the scene captured on the sensor, measured diagonally. It is important to remember that angle of view is entirely determined by both the focal length of the lens and the format of the camera’s sensor, so the angle of view you get from any given lens will be different on 35 mm full-frame and APS-C format cameras. Different lenses of equal focal length will always have the same angle of view when used with the same-size sensor.

This focal length is measured when the lens is focused to infinity (far into the distance). This is because when the lens is focused to infinity, light rays enter the lens almost parallel. When focused on a nearby subject, they enter the lens at an angle.

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A shorter focal length… - Captures more of the scene (= has a wider angle of view) - Makes distant objects appear smaller (= has lower magnification)