When I took some pictures of lightning the other day, I detected severe purple fringing around the lightning path itself. This bothered me, so I investigated.

An interpolated crop of 1200dpi is shown below:

Notice the purple (magenta) colour abberation at the top of the lightning beam, and the yellow abberation at the bottom.

I have read many articles on the web, and if one thing is clear it is that nobody knows for sure why this is happening. Some people attribute it to the lens, some to the sensor. I personally feel it might be a bit of both.

Chromatic abberations in lenses refer to colours not being focussed equally on the focal plane, causing colour shift - where you can see a distinct colour such as magenta, red etc.

Digital cameras' CCD/CMOS sensors can easily be flooded with too much light, causing all sorts of abnormalities in the image.

I am at a loss which one caused this problem in particular, so if someone knows please comment!

Update - 5 Sept '12: I confused the optical phenomenon of chromatic aberrations and purple fringing. Chromatic aberration is correctly defined above as the inability of a lens to focus light rays of all colours at the same focal point in the z-axis. This is not chromatic aberration. This what you see in the picture above is purple fringing, and that happens when too many photons hit the digital camera's CCD/CMOS sensor and starts blooming (leaking) into neighbouring cells. It usually happens between areas of high contrast. This can usually be corrected in post processing using modern tools like Adobe's Lightroom.