How can I reduce purple fringing in-camera when shooting bright lights or backlit scenes?
Asked 10/30/2014
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I sometimes get strong purple fringing around bright highlights, especially in backlit scenes such as sunset reflections on water, and also around bright night lights. In some cases my RAW converter cannot fully remove it, and occasionally the camera JPEG shows it too. I’ve seen this with lenses like a 50mm f/1.8 and a 35mm f/1.8. What causes this, and what can I do before or during shooting to minimize it? Do filters such as polarizers or UV filters help?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
11y ago
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The purple tinge to the lights in your photograph has been caused by longitudinal chromatic aberration, which results when using a wide aperture, meaning the blue and red components of the spectrum are not focused as sharply as the rest. It can also manifest as a green tinge, or even both where there are specular highlights either side of the plane of focus.
To reduce longitudinal CA, use a narrower aperture, or if that's not an option, try to focus manually, using live view if your camera supports it. The fact that all of the lights on the left hand building are showing the same amount of purple fringing suggests that this might be fixable with more accurate focusing (though this might result in green tinges to the lights on the building to the right).
More generally, lateral chromatic aberration, which can result in purple fringing at the edges of the frame, is as Mitch says in his answer, an attribute of the lens and cannot be fixed in-camera (notwithstanding lens profile corrections which apply CA reduction via camera software).
Originally by user456. Source · Licensed CC BY-SA 4.0
user456
11y ago
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Generated from our catalog & community — verify before relying on it.
What you’re seeing is usually purple fringing from chromatic aberration, especially longitudinal CA, which is most obvious with fast lenses used wide open and around very bright or blown highlights.
To reduce it while shooting:
- stop the lens down: smaller apertures usually reduce purple fringing a lot
- avoid blown highlights if possible: slightly lower exposure can help
- be careful with focus: LoCA changes with focus position, so precise focus or live view/manual focus may improve it
- avoid extreme high-contrast situations when you can
- don’t add unnecessary glass: cheap protective/UV filters can make things worse rather than better
A polarizer is not a general fix for purple fringing. It may reduce some reflections in specific scenes, but it does not correct the lens aberration causing the fringe. UV filters are also not a cure.
Some lenses simply show more fringing than others, especially fast primes wide open. If it’s a recurring problem, learn which apertures your lens handles best, or consider a lens with better CA control.
For night lights like your example, the most effective in-camera steps are stopping down, nailing focus, and keeping highlights from clipping.
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AI11y ago
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