What Is Barrel Lens Distortion?

Have you ever taken a photograph where the straight lines bow out and become curved at the edge of the frame? Then you need to learn how to fix lens barrel distortion in photography, which is a common issue that appears when using a wide-angle lens.

While this effect can be appealing in some cases — such as with the artistic photograph shown here — there are many times that you will want to avoid it and have nice, straight lines. This is particularly true when documenting a building, and you need the lines of the architecture to be as straight as they are in real life.

The great news is that barrel lens distortion can be corrected, but first, it is essential to understand why it happens.

What is Barrel Lens Distortion?

Barrel lens distortion is an effect associated with wide-angle lenses and, in particular, zoom wide-angles.

This effect causes the image to spherize, which means that the edges of the photo look curved and bowed to the human eye. It almost appears as though the photo image has been wrapped around a curved surface. It is most visible in images that have straight lines in them, as these lines appear to bow and curve.

Barrel lens distortion occurs because the magnification of the image decreases the farther the object is from the optical axis of the lens. Wide-angle lenses include more pieces of glass that are curved so the portions of the image that are at the edges of the frame can become skewed and will reflect this curvature.

Some lenses, such as fisheye lenses, attempt to take advantage of lens barrel distortion by creating a purposefully curved photo. It is a stunning effect when used for the right purpose and with the right type of subject. Some fisheye lenses are so extreme that the photography ends up being circular in shape, rather than the traditional rectangular shape that's far more common.

How to Fix Barrel Lens Distortion

Barrel distortion can be corrected very easily in modern image editing programs such as Adobe Photoshop, which contains a lens distortion correction filter. Many free photo editing programs also include solutions to the problem.

As distortion is caused by the effects of perspective on the lens, the only way to correct for barrel lens distortion in-camera is to use a special "tilt and shift" lens, which is designed for architectural purposes. However, these lenses are costly, and only really make sense if you specialize in this field.

If you cannot prevent barrel lens distortion with a special lens or if you do not want to do a lot of editing after the fact, you can try to minimize the impact of barrel lens distortion while taking photos.

• Try to avoid shooting buildings or other objects that have clean, straight lines, where the barrel distortion will be obvious. At least try to avoid shooting them with an extreme wide-angle lens. Back up if you need to get more of the subject into the image.
• Keep any straight lines in the image as close to the center of the lens as possible. There will be less distortion toward the middle than there is on the edge.
• As you shoot an object, take several photos of the same subject, using a variety of zoom lens magnification levels. The distortion will likely be less evident at one zoom level versus another.
• Select the RAW format so that you can utilize automatic correction within programs like Adobe Photoshop or Lightroom.

Fixing lens barrel distortion isn't as tricky as it sounds as long as you follow some of the steps here. There may be times where you don't want to fix it, so embrace the distortion! When you cannot avoid it, go with it, and maximize the effect. The curvature of the lines can be enhanced to create a dynamic look in your photograph.