What Causes This Purple Fringing?
The purple or green fringing in your photos is caused by UV light. It's commonly called chromatic aberration. Chromatic aberration happens when all of the light rays don't match up perfectly. This is most evident in lower priced (though still expensive) camera lenses. Older lenses that are not properly coated suffer from this the worst. However even brand new camera lenses made and sold this year can suffer from really ugly chromatic aberration.
In truth every lens can show these ugly purple, blue, or even green fringe. If you're taking photos in really harsh light chromatic aberration is more likely to show up. High contrast situations make it very difficult to entirely eliminate the problem even in very expensive lenses.
How To Prevent This Ugly Purple Fringe
The great news is that you can prevent this ugly purple fringe. Here are my best tips for avoiding chromatic aberration:
- Use the best lens you can afford. Expensive lenses have better coating and other control efforts to prevent chromatic aberration.
- Use your lens hood. This will help keep stray light from causing this fringing.
- Use the best aperture. Test your lens to see which aperture delivers the cleanest photos. Then use this aperture in high contrast situations when possible.
- Use a UV filter. UV light is the hardest to control for. It's the most common cause of the ugly purple fringe. A UV filter will help especially on older or less expensive lenses.
- Try to avoid really high contrast scenes. The lower the contrast the less likely you are to deal with chromatic aberration.
- If you can't prevent it at least you can fix it in a program such as Adobe Lightroom.
How to Fix the ugly purple fringe
Fix It In Camera
Fixing this in camera requires a lens with great coatings and/or a UV filter. Additionally, you can do yourself a favor by composing your photos to minimize purple fringing. You can do that by avoiding objects in your photos which are too high in contrast. Of course, if you can't avoid high contrast objects in your photo you can stop down to a smaller aperture.
Fix It In Post
You can fix the ugly purple fringe after the fact. In fact you can completely fix otherwise ruined photo. Chromatic aberration, the purple fringing can really destroy an otherwise great photo. By using a few tools such as those found in Adobe Lightroom you can remove the fringe or at least remove the color it is casting.
Lightroom Defringe
Lightroom comes with two settings that can help you remove this ugly purple fringe. There is an overall set of tools under the Lens Correction area on the develop tab. This will remove the nasty looking purple fringe from the entire photo. The downside is that it can remove those colors parts of the photos where you don't want them removed.
Lightroom Masking
Additionally under the Lightroom masking tools there is a slider to control fringe appropriately called defringe. It's in the same area as the sharpness and noise controls are. This allows you to mask an area and only remove the fringe in those areas.
Fringe Corrected In Lightroom
Here is an example of the fringe correction done in Lightroom of the photo at the top of this article. You'll see that it no longer has that ugly purple fringe but that areas that have some purple in them are preserved.
As you can see the ugly purple fringe is gone. To do this in the desktop version of Lightroom you need to access the lens correction settings under the development panel. Then click on the manual settings and move the sliders around until you've fix it.
Be Aware
Be aware of what you're doing by zooming in on your photo to one-hundred-percent. This will allow you to more easily see if you're overdoing the correction. Also be careful if you otherwise have a lot of purple in your photo. If so you need to make sure this slider isn't desaturating that other purple.
Congratulations
Congratulations, you now know how to prevent that ugly purple fringing in your photos. If you have any problems I'm more than happy to help. Contact me to ask any questions. Sign up for my mailing list to get more great tips like this monthly. I also teach photography both virtually and in person. If you're interested in a class or private lesson see more on my photography classes page.