Barrel distortion
When photographing with wide-angle lenses, you may notice a lens flaw or aberration known as barrel distortion. This aberration causes straight, parallel lines in a picture to bow outward, which can be seen in the image. The greater the lens's field of view, the more severe the distortion. The result is visually comparable to the impression that would be achieved by wrapping an image around a cylindrical object. It is possible to make the necessary adjustments in the post-capture editing software.
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