A complete guide to lens distortion in photography

The term “distortion” invokes a feeling of something bad in photography, and you could be forgiven for thinking it’s undesired. 

However, while in many situations that may be true, in others, it is not. Distortion can also be used for creative effect. It can enhance or add drama to an image or scene. 

There are several types, so in this guide to lens distortion in photography, we will look at each one and learn when and how to avoid it or use it creatively.

 

What does distortion mean in simple terms?

The dictionary definition of distortion is—“The act of twisting or altering something out of its true, natural, or original state.”

Now, you could argue that every image we take in photography does just that. There is course, an element of truth to this. 

However, there are several distinctive features of distortion caused by the technical aspects of a lens. And these are what we will look at more specifically in this article.

 

Wide-angle lens distortion

To fully understand wide-angle distortion, we first need to understand the concept of wide-angle itself. To do this, we also need to know about lens focal length. 

 

What is focal length?

When capturing an image, light passes through the lens and falls upon the focal plane (sensor or film). 

In an optical zoom, the distance between the lens and the focal plane is known as the focal length, as illustrated here: 

The standard field of view for a digital SLR, mirrorless, or 35mm SLR film camera is 50mm. This is equal to what we see with our eyes. Anything below 50mm = wide angle. Anything above 50mm = telephoto.

 

Crop sensors

Now, this is based on the concept of a 35mm film. However, many digital cameras don’t have a 35mm sensor. 

When they do, it’s called a full-frame sensor (i.e., equal to 35mm film). Other sensors are smaller and commonly known as cropped sensors. These sensors have a crop factor, for example, 1.5x crop factor. 

This means that when you set your lens to 50mm, it’s not equal to 50mm but, in fact, equal to 50 x 1.5—i.e. 75mm. 

So, a cropped sensor’s equivalent standard field of view will be 50 / crop factor. So, for our 1.5x, it will be 50 / 1.5 = 33mm. 

Here, anything below 33mm is wide-angle, and anything above is telephoto.

Related: 9 reflection photography ideas 

 

The wide-angle distortion effect

In the case of wide angle, the distortion effect is warping or bending the perspective of objects in our scene. Wide angle stretches our field of view beyond what is considered normal and thus stretches objects within the composition.

This warping is more evident around the edges of our frame, on larger objects or ones closer to the camera. It also makes foreground objects larger and distant objects smaller.

Photographing buildings up close and looking upwards with a wide angle is the most commonly seen distortion effect. 

The image here was shot at 24mm focal length. The wide angle distorted the vertical lines by bending them inwards towards each other. 

The other distorting effect is that the lower half of the building, which is closer to the camera, has been stretched wider and made larger in the frame, whereas the more distant object, the top of the tower, has been shrunk and looks much smaller. 

The whole tower looks as though it is tapered inwards, although it is perfectly straight.

If you stand there looking with your eyes, there would be a similar effect, only not as pronounced. So, the wide-angle accentuates the distorted perspective. 

 

How to avoid this

If you wish to avoid or minimise this effect, you must move back and higher to shoot more straight at a higher perspective.

This image was shot close and whilst crouched low from an angle:

This image was shot further back, straight on and whilst standing:

 

How to use wide-angle distortion creatively

You can use this effect to accentuate features of a subject, add or create drama to a scene or make things look funny. Here are some uses:

 

1. Adding drama to architectural elements

As seen above, you can shoot from below to accentuate the height of a building or multiple buildings in a city to create a sense of drama. 

 

2. Real estate photography

Real estate photographers use wide angles to ensure the whole room is captured in the photo, but the wide angle also makes rooms appear much bigger.

 

3. Food photography

Ever seen those photos of that big juicy hamburger, only to find that when you buy one and open the package, it’s a shrivelled piece of meat in a big bun? 

Aside from injecting water into the burger to puff it up a bit, they also get right up close with a wide angle to make the meat look much bigger than it is.

 

4. Dramatic foregrounds and skies in landscapes

You can use the wide angle effect to accentuate interesting foreground objects or scenery in a landscape, such as rocks, rivers or roads. The classic use would be to get down low in the middle of a road to make the start super wide and then have it taper off in the distance to some beautiful mountains. 

Wide angles can also emphasise dramatic, stormy skies with interesting cloud formations. They are also great for reflections at sunset, where you can go wide and capture a great flaming sky reflected in a large body of water like a lake.

Related: The 3 essential camera filters (and how to use them)

 

5. Quirky shots of animals & people

The warping effect of wide angles can be used to create fun, quirky shots, too. Such as these here:

  

Telephoto lens distortion

A telephoto doesn’t distort the image like a wide angle does. But it does distort your perception. 

When you zoom in, you isolate a part of the scene and make it look artificially larger. But the other effect is that it can make objects seem much closer and bigger in relation to each other. 

You may have seen those classic images of a rabbit or a stag with a giant moon behind. This is not done using Photoshop but using a 1000mm focal length. 

The images below show the difference between using wide angle and telephoto on the same scene. The first was shot standing close to the grass with a 24mm focal length, while the second was shot from across the road using a 105mm focal length. 

In the wide angle, the grass looks much bigger and longer, and the church is tiny and far off in the distance. 

In the telephoto, the grass is a bit smaller, but more importantly, the church now looks bigger in the picture and closer to the grass.

 

Other types of distortion

1. Chromatic aberration 

Chromatic aberration, or colour fringing, occurs when different wavelengths of light do not converge at the same point. 

This creates coloured halos or fringes around high-contrast edges in an image. 

It can manifest as both lateral chromatic aberration (at the edges of the frame) and longitudinal chromatic aberration (in front of or behind the focal plane). This is easily corrected in post-processing.

 

2. Vignetting

Vignetting is darkening in the corners of an image. It can be caused by limitations in the lens design or when using filters or lens hoods that obstruct some of the light entering the lens. 

It is most common when using wide-angle lenses. Again, it can easily be fixed in post-processing. 

 

3. Lens diffraction

Lens diffraction is a type of distortion caused by small apertures. It affects image sharpness and detail, and it’s important to understand, especially when choosing aperture settings. 

When the aperture is set to a very small size, such as F22, light waves passing through it can be bent when they encounter an obstacle, like a small aperture. 

This causes them to spread out or interfere with each other, reducing image sharpness and producing a soft or blurry image. 

The effect is worse on cropped sensors. Therefore, if using a full-frame camera, you can typically use a smaller aperture than a cropped sensor without the risk of diffraction. 

Every lens is different, but the rule of thumb for avoiding diffraction is to set a maximum aperture of F11 on a crop sensor and F16 on a full-frame.

Related: When to use a telephoto lens (and its effects)

 

4. Barrel distortion

This type of distortion causes straight lines to appear curved outward as if they were wrapped around the surface of a barrel. It is most commonly associated with curvilinear wide-angle lenses and can make images look bulging in the centre.

 

5. Pincushion distortion

Pincushion distortion is the opposite of barrel distortion. It causes straight lines to appear curved inward, creating a pinched or cushion-like effect. This type of distortion is often seen in telephoto lenses.

 

6. Fisheye distortion

Fisheye lenses produce extreme barrel distortion, resulting in a circular or hemispherical projection of the scene, like looking into a fishbowl. Therefore, this effect is intentional and used for creative or artistic images.

 

8. High ISO distortion

As you increase the ISO on your camera, you introduce noise into the sensor. Therefore, high ISOs are a type of distortion. 

How bad this noise can be depends on the camera you use. Higher-end cameras perform better at high ISOs than cheaper ones. Also, camera manufacturers are making massive improvements in this area. 

Noise is more obvious in the darker areas of your scene, too. Noise can be reduced in post-processing, and there is also some great software out there, such as Topaz Denoise, that does an excellent job. 

That said, you will lose sharpness and end up with a softer image. So be sure to only use a high ISO whenever there is no other choice.

 

How to correct lens distortion

As explained earlier, some distortion, although not all, can be corrected in post-processing. 

Buildings and objects can often be straightened using Adobe Camera RAW, Photoshop or Lightroom. 

However, be sure to leave plenty of room around the edges of your photo, as much of it will be lost in the process.

 

About the author:

Ian Middleton is a travel and landscape photographer and writer. He is the author of several books, including a practical guide to photography. His photography has been used in numerous publications worldwide and is sold as high-quality wall art online.

Visit his website for more info: https://ianmiddletonphotography.co.uk

 

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