The Lens Corrections pane contains controls for fixing Chromatic Aberrations and Lens Vignetting. These are the same controls found in Adobe Camera Raw and can also be mimicked using Photoshop's Reduce Noise and Lens Correction filters.
Chromatic aberrations (CA) show up as anomalous color shifts, mostly on the outer perimeter of an image, in areas with distinct edge transitions. The fringing is sometimes there because when light passes through glass, different color wavelengths are separated and shifted in focus ever so slightly. They are mostly evident when wide-angle lenses are used, but can appear with longer lenses as well.
This image of a huge Icelandic power plant was taken near our hotel in Nesbud. Figure 4-73 Although the chromatic aberrations are not visible at first glance, Figure 4-74 magnification shows some annoying anomalies on the edges. Figure 4-75
This is how to reduce CA:
Magnify the image to at least 100 percent to Identify the color fringing. (An [ ! ] icon appears if you are below that magnification setting. Click on the icon to automatically ...