How to Fix Radial Distortions on Lenses

If you’ve ever looked at an object or a scene through a long lens, and then adjusted to an even longer lens and then again to an even longer one, you might have noticed how the scene or object can be pinched or pulled into various distorted ways with each of the lenses. The distortions occur as a result of the varied physical distance that sites between your camera sensor and the actual individual on camera. Lens distortions are sometimes frustrating for photographers, but their effects are frequently sought after in cinematography. Learning how to fix radial distortions on lenses will not only help you to better understand the impact of radial distortions on your footage but also what you can do to create, or eliminate, radio distortions in production.

What is Radial Distortion on a Lens?

Radial lens distortion results when there are imperfections in the curvature of the lens that occurred during the original production of the unit.

Radial distortion errors produced by the lens are usually around 1 or 2 um whereas the scanning resolution of the image captured by the lens is typically around 25 um, thus the distortions are much smaller than the resolution. 

Radial lens distortion for digital cameras is often higher than that of professional quality camera systems. Thus, the optical deviation occurring from rectilinear projection is typically greater with these types of cameras and will often cause more significant radial distortion.

You might have heard the term radial distortion described in the following ways:

• Barrel distortion: which occurs when the magnified image increases in a nonlinearly fashion from the optical axis which will cause the view to be more of an outward bulge.
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• Pincushion distortion: which occurs when the straight lines of the image curve out from the center causing the appearance of magnification of items close to the edge of the image frame.
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• Mustache distortion: which occurs when there is a mixed level of distortion in which elements of both pincushion distortion and barrel distortion appear present causing vertical lines to curve in towards the center and then back out towards the corner of the frame.

How to Fix Radial Distortions on Lenses

So, you want to know how to fix radial distortions on lenses? The lens itself has no exact fix as the distortion results from the error which is produced in the manufacturing of the lens.

However, there are some things that cinematographers and photographers can do to reduce or eliminate radial distortions in their footage. 

Fixing barrel distortion requires the use of a post-production editing program. The same holds true for fixing radial distortions such as the pincushion distortion. Adobe products, including Lightroom and Photoshop can reduce radial distortions that occur in still images.

Distortions of this type are typically produced to create emotional value in cinematography, thus a fix may not be sought after.

Learning how to fix radial distortions on lenses by adjusting your position and altering the distance from which you shoot your subject or changing the lens to utilize a longer lens represent two very easy solutions that can be extremely helpful.

However, both of these solutions may impact your composition and framing so keep this in mind and decide whether you’re okay with potentially having more background present in your image.

Fixing lens distortions is all about understanding the various types of distortions and causes, and recognizing the steps that you can take early on to avoid distortions that negatively impact your composition and framing.

Keep in mind that learning how to fix radial distortions on lenses is something that you’ll just have to continue to work on as you continue to evolve with your cinematography skills.