What is lens distortion in photography? How to avoid or fix it

Sunflower Distortion through glass

We all want a camera with as many megapixels as possible. But, image quality is much more than resolution. From noise to poor composition and chromatic aberration, there are many things to avoid to get excellent quality photos.

One such problem that you will often encounter is lens distortion. If you’re a beginner photographer, you probably won’t even notice. But it is good to know what it is and the necessary steps to address it.

What is lens distortion?

We say an image is “distorted” when lines and shapes appear distorted. This is caused by problems with the lens or by how the lens is designed.

The lens is made of many optical elements that refract and bend light rays. Sometimes, the geometry of the lens can cause image distortion. Distortion is common in low-quality lenses, but even expensive lenses can suffer from distortion.

If you are a fan of wide-angle lenses, you will know that distortion is typical in them. This is because the camera sensor’s field of view is often smaller than that of a wide-angle lens, so the edge of photos looks crooked. Regardless, there are many benefits to owning a wide angle lens. Fisheye lenses are designed to purposefully distort images.

Types of lens distortion

Before knowing how to correct lens distortion, you must know the types of distortion. Different types of distortion will need different correction techniques.

There are two main types of lens distortion.

optical distortion

This type of distortion is caused by the optics of the lens. A standard lens is meant to be straight, with straight lines appearing as straight lines without any distortion. However, if the lens is curved, straight lines appear curved. A fisheye lens is a perfect example of a curved lens.

Although standard lenses are designed as straight lenses, all lenses suffer from varying degrees of distortion.

Optical distortion can occur in three ways.

barrel distortion

In this type of distortion, the straight lines bulge outward to take the shape of a barrel. Cylinder distortion occurs frequently in wide-angle and wide-angle zoom lenses because its field of view is often larger than that of the camera sensor. Therefore, the corners end in the frame.

When the lens has a cylindrical distortion, the images look as if they are stretched in the middle but squeezed in the corners.

distortion of the pillow

Imagine a pin cushion – you can see the pin pulling the corners inward. Similarly, you will notice straight lines bending inward in the distortion of the pillow. It appears to be the exact opposite of barrel distortion. The culprits are the opposite of wide-angle lenses – telephoto lenses, especially zoom lenses.

A telephoto zoom lens disproportionately magnifies objects in the corners of an image, so you see corners extended but a pinched center.

Mustache distortion

This type of distortion is a combination of cylinder and pin distortion. In mustache deformity, the straight lines at the corners curve inward while the lines in the middle bulge outward, shaped like a mustache.

It’s a complex distortion that’s hard to correct, but you’re more likely to encounter only in older lenses.

Perspective distortion

This type of distortion has nothing to do with the lens. Instead, it happens due to the position of the camera and the distance from the subject.

Extension (wide angle) distortion

Have you tried using the wide angle lens for portraits? You will probably hate the result. A wide-angle lens can make faces appear unnaturally large. But this is not the fault of the wide-angle lens. The problem is that you are too close to your subject.

In general, things that are very close to you will appear larger. This is because you tend to stay very close to the subject with a wide angle lens. When you use a telephoto lens, you are forced to back away from your subject. This is why telephoto lenses are one of my favorite lenses for portraits.

In short, span distortion expands the space between foreground and background.

Also, when using wide-angle lenses to photograph tall buildings, they tend to appear wide at the bottom and merge at the top. This is caused by the viewing angle, and the part closest to you appears disproportionately larger.

Compression (telephoto) distortion

In compression distortion, distant objects appear unusually large. Basically, it is the opposite of extension distortion and occurs in telephoto lenses.

Compression distortion closes the space between the foreground and background, making the image appear compressed.

How to correct lens distortion

You can correct common deformations such as barrel and pad using post-production software. For example, Lightroom has a Lens Corrections option. When checking Enable Profile Corrections, the software can find your lens in the database with the metadata and apply the correction automatically. Here is a guide on using lens corrections in Lightroom.

On the other hand, a mustache deformity will require a special program to correct it.

To correct perspective distortion, your best bet is to check the distance between you and your subject and adjust accordingly. For example, don’t get too close to your subject when using a wide angle lens to avoid distortion of the extension. And for telephoto lenses, choose a wide aperture so that the background details are blurred.

If your photo is badly distorted, you can use Lightroom’s transform tool to fix it. It works well for perspective distortion.

Technical use of distortion

You can definitely leave your image distorted and call it artistic freedom. Lenses such as fisheye and tilt offset are made for this purpose. It’s good to know what kind of distortion you’re dealing with and then decide what to do with it.

Ultimately, it is up to you as a photographer to decide how you want your photos to look. But know the rules before you break them.

Learn the basics to avoid lens distortion

All lenses have some kind of distortion due to their design. It’s not a big deal, but it can be annoying. However, you can easily avoid them by paying attention to the distance and angle from where you shoot. Also, invest in quality lenses to reduce distortion in your photos.

If all else fails, you have post-production software to the rescue.

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