Everything You Need to Know About Focal Length

We explain focal length in relation to camera lenses in depth and detail.

by M. Yates
on May 12, 2018

Photography can be very technical. In fact, some of the basic characteristics of photography may seem like they are pulled out straight from rocket science. Thankfully, photography can be mastered by tackling each aspect one at a time.

In this article, we are going to cover what focal length means. Also, we are going to cover some tips on how you can use varying focal lengths to bring out that "perfect image" you have in your mind.

Focal Length: what does it mean?

There are different ways of defining what focal length is all about, and here's one:

Each lens has a focal length, and it determines the "zoomed-in" level of your images. When it comes to the focal length number, the higher the number is, the more zoomed-in the lens will be.

Keep in mind that focal length is usually expressed in millimeters. It's a common misconception that focal length number is the distance between the lens and the film or sensor. In reality, the focal length is the distance between the film or sensor and the "point of convergence."

Focal Length: why is it important?

Keep in mind that a camera does not "see" the way a human eye does. For humans, we tend to focus on a small area, while the rest is in a "peripheral vision." The human brain has developed in a way that it knows how to separate what is perceived as important and what's not important (like how you usually don't pay a lot of attention to peripheral vision).

A camera, on the other hand, doesn't have this kind of ability. This means that the job of separating what to include and what not to include lies on the photographer. As a photographer, you usually deal with the subject and the background to create a "scene."

How these two elements relate to each other can significantly impact how the image is presented. One of the ways to manipulate this "relationship" between the subject and the background is through the proper use of focal length.

Focal lengths generally play with the element of perspective. For example, a certain focal length allows you to capture more elements in a single image, like how you pack more items in a single bag. However, when the camera does this, it usually sacrifices something else. In this example, it usually sacrifices depth and "realism." Check out our article on depth of field and aperture for more details on this.

On the other hand, there's a certain focal length that exceedingly highlights the subject to the point that everything in the image "drops out."

You can think of varying focal points as several tools in your toolbox. As a photographer, it's your job to find the right tool for the job.

The Common Focal Ranges and Its Uses

The 14-24mm Ultra Wide

The 14-24mm Ultra Wide lenses are often considered as "specialty lenses." This means you won't likely find them in a kit lens.

Ultra wide lenses capture a wide-angle view. The resulting images are often seen by the viewer as somewhat distorted as the human eye is not used to seeing such a wide view.

Ultra wide lenses are generally used for architectural and event photography. This is because ultra wide lenses are capable of fitting a lot of elements in a relatively small space. You can say that an ultra wide lens is used for putting the subject in the "middle of everything," rather than capturing the subject while the scene is "supporting" the subject.

Ultra wide lenses are generally not suitable for portrait shots. This is because the lens will "enhance" the perspective to the point that facial features will look unnatural.

24-35mm Wide Angle

Most full frame kits will already include wide angle lens, especially the 24mm. This is because the 24mm is the point in which you'll be able to maximize the side parts of the image while not making it look unnatural. A wide-angle lens is often used by photojournalists as the lens is able to capture a lot of elements in an image while still making the image appear realistic.

35-70mm or the "Standard"

When it comes to capturing images that are very close to what the human eye can perceive, the best focal length to use is the 35-70mm range, especially the 45-50mm range. It's also the reason why this focal range is considered as the "standard."

The standard range is best for confined settings like friends in a dinner table or street. The 50mm is particularly inexpensive, and it produces excellent images. Keep in mind that lenses with fixed focal lens and can't zoom (also known as prime lenses) will generally produce better results when compared to a kit lens. This is because a prime lens does one thing, and it does an outstanding job at it. On the other hand, a kit lens is more of a "does multiple things with an okay job at each one."

70-105mm Mid Telephoto

For portrait telephoto primes, the range stops around 85mm. Mid telephoto lenses are best used for portrait shots. This is because the mid telephoto comes with a "perspective" of separating the subject's face from the backdrop or background without totally isolating it. If you are looking for a cheap vlogging camera, try to save money by buying one with a single lense in this range.

105-300mm Telephoto

This type of lens is often used for capturing distant images and has the strongest magnification. Because of how a telephoto "flattens" the scene's perspective, it's not also good for landscape shots. Telephoto lenses are generally used if you want something that is sort of a "close-up" shot, but taken from a distance, which is why it's primarily used for wildlife and sports photography.

Conclusion

In technical terms, the focal length of a lens is the distance between the point of convergence and the film or sensor. Camera lenses come in different focal lengths, usually expressed in the form of millimeters. Photography is similar to painting in a way that you use a specific type of brush for a specific effect or task. Focal length is just like a painter's brush, and how and what to use will have a tremendous impact on the result of your images.