Axial chromatic aberration
From The Glossary of Digital Photography
Also called longitudinal chromatic aberration. Appears in a digital image as purple fringing. If the fringing is on all sides of an object, it is axial chromatic aberration. If the chromatic aberration is purple on one side of an object and green on the other, it is lateral chromatic aberration. Another aspect of axial chromatic aberration is that it is more affected by the f-number of the lens in use. The purple fringing tends to increase as the lens is stopped down. See also fringing; lateral chromatic aberration
