What is Focal Length in Photography? Choosing a Focal Length

In this guide, we’ll be diving into everything you need to know about focal length in photography.

What is Focal Length in Photography?

The focal length is defined as the distance between the camera’s optical center (also known as its nodal point) and the camera’s center.

Any photographer needs to have a working knowledge of focal length to shoot successfully.

The focal length of a lens determines the distance needed between a subject, in order to photograph with precision.

Without an understanding of camera focal length, photos risk appearing overly distorted or compressed.

Essentially, the focal length is the lens’ optical property. Typically represented in millimeters.

focal length example
focal length represented in millimeters (mm)

A camera sensor is a hardware that captures light and converts it into an image. A 35 mm full-frame sensor type is generally favored among photographers.

Focal lengths are integral to photography because they indicate how ‘zoomed in’ an image appears.

Once you know how focal lengths affect and relate to elements like zoom, perspective, and range, you can get creative with how you manipulate these features.

Before we continue, it is useful to go through several photography terms that are relevant to a focal length:

1. Angle of View

The amount of a scene captured by a camera’s sensor.

2. Zoom

Making an element appear closer without moving the camera.

A powerful zoom can close in on an element without compromising the sharpness of an image.

3. Perspective

The sense of depth or spatial relationship between objects in an image. Focal lengths greatly impact depth in an image.

4. Range

Also referred to as dynamic range, it is the ratio between white and black light intensities, or the maximum and minimum tones in an image.

5. Aperture

Aperture is the opening of a lens where light passes through. Think of it as the pupil of an eye.

The angle of view, zoom, perspective, range, and aperture are only a few important photography aspects related to focal length.

Each element should be taken into account when considering what lens to use.

To further explore the subject of focal length, check out this in-depth video by Saurav Sinha:

Focal Length Explained! Why does it MATTER?

What are the Lens Types?

Lenses are generally categorized into two types according to their zoom capabilities.

Deciding between the two usually comes down to personal preference and the photography genre.

1. Prime Lens

Prime lenses have fixed focal lengths, meaning that there is no zoom feature and a more limited distance range for images.

We have a full guide on prime lenses, so be sure to check that out!

A significant advantage of a prime lens is its ability to capture more light due to its wider maximum apertures.

This makes them great for shooting in an environment with poor weather or dim lighting.

2. Zoom Lens

A zoom lens is versatile because you can try various focal lengths with just one lens. They are a standard lens type for beginners.

We have a full guide on zoom lenses, so be sure to check that out!

Let’s dive into the different lens focal lengths and how they affect composition, range, and perspective.

What are Different Focal Lengths?

Simply put, a longer focal length shows a smaller angle of view and larger magnification and a shorter focal length offers a broader angle of view and decreased magnification.

short vs long focal length
shorter vs. longer focal length

It is also important to note that while the lens controls the angle of view, the field of view is influenced by the focal length and the camera sensor.

1. Ultra Wide-Angle lens

An ultra-wide-angle lens measures 14 mm in focal length and usually exaggerates perspective in photography.

Which makes it popular for shooting outdoor scenes like architecture or streets.

Photographers tend to use a lens with an ultra-wide-angle when they want to capture as much of a scene as possible.

A fisheye lens is an ultra-wide-angle lens that dramatizes an image, plays with the distance between objects, and provides a unique perspective to images.

abstract photography fisheye lens
using a fisheye lens

2. Wide-Angle Lens

A wide-angle lens has a range between 24-35 mm in-camera focal length.

Similar to an ultra-wide-angle lens, it makes objects look smaller and can contain more within a frame.

A wide-angle lens is most often used when there is a large field of depth, making it perfect for shooting landscapes or cityscapes.

3. Standard Lens

A standard lens has a focal length range between 35-70 mm. It is generally thought to be a good choice for beginners.

The most common standard lens is the 50 mm; it is also called mid-length.

The 50mm is said to have a similar perspective and angle of view in comparison to the human eye.

Lots of portrait photographers rely on standard lenses, but they can also be utilized across an extensive range of image genres.

4. Telephoto Lens

A telephoto lens can range from a 70-300 mm camera focal length.

It shows shallow depth and compresses the view, so it is typically used in environments where a photographer is at a far distance from their subject.

For example, wildlife and sports settings. Beyond this, a super-telephoto lens exceeds a 300 mm focal length.

Why is Focal Length Important in Photography?

Two important photography parameters, such as magnification and angle of view, are determined by the focal length of the lens.

Photographers place a high value on it. Higher magnification corresponds to larger focal lengths and vice versa.

The camera’s focal length affects not only how much of an object you can capture, but also how large your objects will appear in a photo.

How do you Choose Focal Length?

Every photographer should choose a focal length according to their needs.

The appropriate focal length is determined by the filming genre, location, and artistic vision of the photographer.

Remember – the shorter the focal length, the more of a scene is captured. The longer the focal length, the less of the scene is captured.

1. Wide-Angle Lenses

Wide-angle lenses (24mm – 35mm) are ideal for photographing landscapes, cityscapes, architecture, auroras, and the Milky Way.

Wide-angle lenses are also good for indoor photography.

2. Fisheye Lenses

A fisheye lens, also known as the ultra-wide-angle lens (4mm – 24mm), offers an enormous field of view and is mostly utilized for creative purposes.

3. Standard Lenses

Standard focal length lenses (35mm – 70mm) are good for street, travel, and portrait photography.

4. Short Telephoto Lenses

Short telephoto lenses (70mm – 135mm) are preferable for street photography and portraits.

5. Medium Telephoto Lenses

Medium telephoto lenses (135mm – 300mm) are great for photographing wildlife, sports, and action shots.

6. Super Telephoto Lenses

Super telephoto lenses (300mm+) are used to photograph sports from a distance, as well as nature and the night sky.

Professional wildlife, sports, and astronomy photographers can benefit from telephoto lenses.

However, keep in mind that telephoto lenses are heavy and may require the use of a tripod to support them.

Such lenses might not be suitable for amateurs, as they may exceed their budget.

To further explore the subject of choosing the correct focal length, check out this in-depth video by Wolf Amri:

What lens shall I buy? Focal Length - Learn how different focal lengths change your image

How is Focal Length Calculated in Photography?

Finding the focal length of a modern lens is easy. The information is always printed on the lens.

However, this does not apply to vintage lenses, so the focal length needs to be calculated manually.

The standard focal length formula is:

1/Focal length = 1/Image distance + 1/Object distance,

focal length formula
focal length formula

where Image distance and Object distance are provided in mm.

What is the Focal Length of a 50mm Lens?

The focal length of a 50mm lens on a full-frame camera is 50mm.

If you have a crop sensor camera, you should be aware that a 50mm lens will act differently.

For example, if you use a 50mm lens on a crop sensor camera with a crop of 1.5x, you must multiply 50 by 1.5, meaning that the actual focal length for a 50mm is 75mm.

Final Remarks

Consider each element carefully before selecting the right lens and experiment with different focal lengths.

There are many nuances when it comes to focal length. It could be fun to try out different focal lengths, in order to see how they impact your image.

Still unsure about what to choose? Start standard and branch out from there. There are so many possibilities!

To get a better idea of what different focal lengths look like in action, take a look at some royalty free stock footage.


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