Originally Posted by Alex Leith (Post 853654)

Chromatic abberation.... a side-effect of the fact that different wavelengths (colors) of light resolve at different points (because they bend different amounts) when they pass through a lens. It results in a red-blue or magenta-green fringe most visible on high-contrast edges, especially at the edges of the image.

Zoom lenses suffer more than primes as zoom lenses pass the light through more lens elements.