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Lens distortion is made by optical principles. Barrel distortion is common with wide-angle and pincushion distortion that appears with telephoto. How can I avoid this when shooting? Are there any shooting techniques for these distortions? Let’s briefly discuss them.

Barrel Deformation and Pincushion Deformation

If a barrel-shaped deformation occurs in the photo, the image point will shift as the distance from the center point increases, causing the middle portion of the in the image to bend outward, and the two ends will bend toward the center to become a curve. Therefore, the image of a square object will shrink inward at the four corners, and the middle of the side-line will protrude outward, like a wooden barrel. Hence the name “barrel deformation”. Generally, as the angle of the lens increases (that is, a wider angle or a shorter focal length, such as a focal length of 10mm), barrel distortion will become serious. The pincushion deformation is the opposite, the picture will shrink toward the center, which is common at the telephoto end (such as 250mm focal length).

Example of barrel deformation

Example of barrel deformation

Application Examples of Lens Distortion

Pincushion deformation is less commonly used, but barrel deformation is more widely used because barrel deformation often brings out exaggerated effects. Please see the following for examples.

“Big Dog” Effect

The “red dog” that was extremely popular is an example of barrel deformation. It is best to use fish-eye glasses (a super wide-angle lens with a focal length of 10mm) to highlight the effect when shooting “big dog” photos. Distance shooting to make an exaggerated effect of head and body.

Big head dog

Bighead dog

Characters Stretch their Hands and Feet

Because the barrel deformation will expand the objects around the photo outward, if the hands and feet of the person are placed at the edge of the photo, the hands and feet will be stretched. With the shooting technique of the low position,  model’s feet will appear more slender! In addition to making special effects, people’s faces should be placed in the middle when taking such photos to avoid being affected by deformation.

Under the deformation effect, the model's feet are longer!

Under the deformation effect, the model’s feet are longer! Photo from Mobile01

Avoid and Correct Lens Distortion

Sometimes we don’t want the scene to be deformed by the lens when we take a photo. There are two ways to avoid and correct it:

(1) Avoid Extreme Focal Lengths

Because lens distortion mostly occurs at wide-angle (<18mm) or telephoto (> 250mm), we can use the middle focal length to shoot. Note that the more the scene is placed at the edge of the screen, the stronger the distortion effect, so if you don’t want to shoot the subject with the lens distortion, you can place the subject in the middle part of the photo.

Nikkor 10.5mm Ultra Wide Angle Fisheye Lens

Nikkor 10.5mm Ultra Wide Angle Fisheye Lens

(2) Correcting Lens Distortion using Software

If barrel or pincushion distortion is found after shooting, it can actually be corrected using software. The recommended software is the “Lens Correction” filter of Photoshop CS2 and the “Deformation Correction of Light and Magic” “Tools, the correction process for this two software is also very easy to understand. But note that after correcting the photo, you need to crop the photo again to maintain the proportion, so the photo will be reduced.

Photoshop corrected photos

Photoshop corrected Photos

 

 

Author: Alex Tam