Lens distortion is a bending of straight lines in an image, caused by how a lens maps a flat scene onto a flat sensor. Barrel distortion makes lines bow outward like the sides of a barrel, while pincushion distortion pulls them inward toward the centre. Both can be reduced in editing or sometimes by how you shoot.
Barrel Distortion
With barrel distortion, magnification drops toward the edges, so straight lines near the frame border curve outward. It is common in wide angle lenses and at the wide end of zoom lenses. Fisheye lenses use it on purpose to fit a very wide view into the frame. In everyday shots it shows up as a curved horizon, bowed door frames or building edges that bend away from the middle.
Pincushion Distortion
Pincushion is the opposite. Magnification grows toward the edges, so lines bend inward toward the centre of the picture. It tends to appear at the long end of zoom lenses and in some telephoto designs. You may notice it when photographing a grid, a bookshelf or a window with long lenses.
Mustache Distortion and Zooms
Some lenses show both at once, with barrel in the middle and pincushion toward the edges. Lines then take a wavy shape, and this is often called mustache or complex distortion. Zoom lenses commonly move from barrel at the wide end to pincushion at the long end, with a nearly flat point somewhere in between.
How to Reduce It
- Turn on lens profile correction in your raw editor, since most programs include profiles for popular lenses.
- If your camera offers in-camera distortion correction, enable it for JPEG output, and check what it does to the edges of the frame.
- Use manual distortion sliders when no profile exists, adjusting until a straight edge near the border looks straight.
- Keep important straight lines away from the extreme edges when you compose.
- Level the camera. Tilting up or down creates a separate effect called perspective convergence, which is not lens distortion and needs a different fix.
| Type | Lines bend | Often seen with |
|---|---|---|
| Barrel | Outward | Wide angle and wide zoom settings |
| Pincushion | Inward | Telephoto and long zoom settings |
| Mustache | Wavy | Some wide zooms and retro designs |
FAQ
Does correction lose image quality?
Digital correction stretches the picture slightly and may crop the edges a little, but for most uses the effect is minor.
Is distortion ever useful?
Yes. Fisheye work, dramatic wide interiors and some creative portraits use it for effect, so correct it only when it hurts the picture.
The Short Version
Barrel distortion bows lines outward and is common on wide lenses. Pincushion pulls them inward and is common on long lenses. Use profile correction first, then fine tune by hand when a lens has no profile.
