Wednesday, February 4, 2009

Watch out for aberrations!

Building on my previous post about the importance of light color, (What’s with all the red lights?) let’s take a moment to discuss what’s wrong with white light.

Back to basics: There is of course no such thing as ‘white light’. That which we perceive as white is in reality a mixture of all wavelengths. And that’s potentially a problem.

The problem stems from the property of refraction. You know that light bends when it passes from one medium to another. In fact that’s why a lens works. But did you know that the amount of bending is proportional to the wavelength of the light? What this means is that blue light bends more than red light. Now the lens designers know this, so they try to design it out, but depending on the quality and focal length of your lens, it’s still there to a degree. This is what’s called ‘chromatic aberration,’ and it will reduce the quality of your image.

So the takeaway from today’s spiel is this: monochromatic light will give a better quality image than will white light.

No comments: