Complete Focal Length Guide

Last Updated on March 16, 2021

When selecting a lens one of the most important factors to consider is the focal length. The focal length of your lens lets you know the distance from your subject you need to be when you shoot. For more info for getting started in photography read the beginner photography guide.

Simply put, the further your subject is away from you, the longer the focal length you will need. While using a smaller focal length is ideal for capturing the detail of the scene closer to you.

Understanding Focal Length is very important

focal length chart

When selecting a lens for your camera it is imperative that you understand how focal length works in relation to your camera. Lenses come in two styles of focal lengths, either a fixed focal length or a variable focal length. A fixed focal length is referred to as a prime lens while a variable focal length model is a zoom lens.

Prime lenses are equipped with a wider aperture making them ideal for shooting in low light conditions while a zoom lens makes it possible to shoot from multiple distances effectively. Both prime lenses and zoom lenses come with their own special pros and cons. So understanding their shooting strengths and weaknesses is important for ensuring you get the best shot possible for the environment. Most photographers will have both prime and zoom lenses on hand to ensure they are prepared for all shooting situations.

What Does Focal Length Mean?

The focal length of your lens denotes the level of zoom in on a subject can be. This means that the higher the focal length is the greater the distance you can effectively shoot from.

The focal length of your lens is specifically a measurement of the distance from the point of convergence of your lens to the sensor or the film in your camera. It is not a measurement of the distance of the front of your lens to the back of your lens, which is a common misconception.

What Focal Length Should You Use?

focal length difference example

14-24mm Ultra Wide: Fisheye Lens

Fisheye lenses are a cool style that is not shot with frequently but can produce interesting shots so understanding when to use it is important. These lenses utilize a very wide angle view which creates a distorted image. This distortion is due to the lens fitting more of the shot into the sensor than a normal lens angle would.

Ultra wide angle lenses are used most frequently in situations where space is limited for getting everything in your shot such as shooting architectural photography. They are also used by action and some sports photographers. Using this lens makes a bold statement so use it sparingly. It would not usually make a great choice for shooting portraits for example.

24-35mm Wide Angle Lens

The wide angle lens is one of the most widely used lenses you will find. They are often included in full frame camera kits so you may already have a wide angle lens. Because image distortion becomes unnoticed by the eye at 24mm this lens is great for shooting clear images such as those of real estate, photojournalism, and many other styles. These lenses are wide enough to capture most scenes without getting too much distortion.

35-70mm Standard Lens

A standard lens is the one that reproduces images that closest resemble the images produced by the human eye. This focal length can produce intimate images that have an almost cozy and natural feel.

Shooting a standard lens is great for street photography, parties, or family settings. You can find both zoom and prime lenses in this focal length range. While a variable focal length lens in this range can produce fine image quality, to achieve the best image quality possible I recommend getting a 50mm prime lens for most of your shooting in this range.

70-105mm Mild Telephoto Lens

Telephoto lenses usually are not included when a camera kit is purchased so you likely will have to invest in new lenses for the rest of the focal lengths. The 70-105mm focal length range is ideal for shooting portrait photography. These lenses will maintain a natural perspective ideal for portraits making it possible to separate the subjects face from the image background.

105-300mm Telephoto Lens

I shoot a lot of landscape photography and this focal length range is ideal for shooting at distances. These lenses are ideal for shooting cityscapes, mountains, sporting events, and pretty much all landscapes. I also use these lenses for a good portion of my nature photography.

Focal Length and It’s Effects on Perspective

focal length and depth of field

I discussed this earlier but I want to just make sure this is very clear. It is important that you understand that it is not that the focal length that changes your perspective. What is really going on is that it is your distance from your subject that changes your perspective, and that distance is dictated by your focal length.

In other words, your lens’s focal length tells you what your distance from your subject should be. The framing of your subject does not change because of your focal length, just your distance from your subject changes.

Sensor Type Effects on Focal Length

If you are shooting a crop sensor camera then it is important to understand that if you attempt to shoot with a full frame lens that your image sensor is still using a cropping effect. This will directly effect your functional focal length. Because the crop factor is 1.6x, you must calculate your functional focal length by multiplying your lens’s focal length by 1.6. This will give you your effective focal length when pairing a full frame lens with a crop frame camera.

An important note. Some crop lenses also have this effect. Lenses in the EF-S and DX range must also be calculated for an accurate focal length. These particular lenses use their actual length as opposed to their field of view.

Focal Length Wrap up

Now you have a solid understanding of focal length and how it impacts your lens selection. Use the lens guidelines above when making your lens choices and you will be solid. As you progress as a photographer you will likely accumulate many different lenses and depending on your shooting style, some will be used more than others. But if you are just starting out don’t fret not having a ton of lenses. The most important thing is to select a solid couple lenses that you will use frequently and build your lenses over time as you better understand what you need. Happy shooting!