Chromatic aberration is the coloured fringe, often purple, green or blue, that can appear along high-contrast edges in a photo. It happens because a lens does not bring every colour of light to exactly the same point. You can reduce it by changing how you shoot or by using a correction in editing.
Why Colours Separate
White light is a mix of colours, and glass bends each colour by a slightly different amount. A simple lens therefore focuses red, green and blue at slightly different spots. Lens designers combine several elements and special glass types to pull the colours back together, but the match is rarely perfect in every situation.
The Two Main Types
- Longitudinal (axial) aberration: colours focus at different distances from the lens. It shows as fringes in front of and behind the focus point, usually with one colour on one side and another colour on the other. It is most visible with wide apertures.
- Lateral (transverse) aberration: colours focus at different positions across the image. It shows as fringes that run along edges toward the corners, with the colours on opposite sides of an object. It does not change much with aperture.
Purple fringing is a related term often used for purple or magenta edges around bright areas. It can have several causes, including sensor behaviour, so it is not always pure chromatic aberration.
Where You Notice It
Look at edges where a bright area meets a dark one, such as tree branches against the sky, window frames, metal reflections and backlit leaves. Zoom in to one hundred percent on your screen and check the corners first.
How to Reduce It
- Close the aperture a stop or two to lessen axial fringes.
- Avoid very high-contrast edges at the border of the frame when you can.
- Turn on the lens correction option in your camera if it offers one, or apply a lens profile in your editing program.
- Use a defringe or chromatic aberration removal control for stubborn cases, working carefully so that real colours in the scene are not drained.
- Shoot raw files so these corrections can be applied without extra quality loss from compression.
Comparing the Fixes
| Method | Best for | Limit |
|---|---|---|
| Smaller aperture | Axial fringes | Little effect on lateral fringes |
| Lens profile | Lateral fringes | Needs a matching profile |
| Manual defringe | Leftover edge colours | Can alter real colours |
FAQ
Does a more expensive lens always avoid it?
Not always. Better glass and design often keep it lower, but any lens can show fringes in harsh light. Checking your own pictures at full size tells you more than a label does.
Can I see chromatic aberration in a printed photo?
Often not. At normal viewing sizes small fringes disappear, though they can show up in large prints or when you crop in heavily.
The Short Version
Chromatic aberration is a colour fringe caused by glass bending colours differently. Narrow the aperture, use a lens profile and apply a light defringe if needed. Most cases are easy to fix once you know which type you are seeing.
