Archive for May, 2008

Polarization and Hair Color

Tuesday, May 27th, 2008

I’d like to share something that I’ve observed quite often in my experiences with a polarizing filter, but that is not a common topic of articles that I’ve read. I hear a lot about polarization’s abilities to reduce glare, darken the blue in the sky, and enhance the greens in plants. However, rarely do I hear about it’s ability to make hair color (particularly red) significantly ‘pop.’

A circular polarizing filter is like a pair of polarized sunglasses for your camera. Polarization relies on the fact that certain forms of light (such as most reflected light) travel in a uniform manner. Due to this consistency, a polarized lens is able to filter out a specific group of light waves while allowing the remaining light waves (usually what we care about) to pass through with less disturbance. To illustrate this behavior, here’s a quick example of what polarization is most known for: it’s ability to significantly reduce, and sometimes completely remove, reflections so that you can see “through” glass and water.

Glare and reflections obscure subject matter without a polarizing filter.

A polarizing filter can reduce glare and reflections.

The two pictures above are from a recent trip to Rome where I caught three police officers reading about a soccer match in their car. You can’t see the third officer in the passenger seat in the first picture because of some intense reflections on the windshield. But with the polarized filter adjusted correctly in the second picture, the reflections are almost completely removed and the light waves that I care about (those bouncing off of the person in the car) are able to hit my camera’s sensor without the interference of the reflections.

Now let me show you an interesting example of how this same process of reducing reflections in shiny hair can significantly saturate it’s color. The following pictures have not been graphically altered and are straight out of my camera. The difference you see in the colors are a result of the polarizing lens blocking out the reflections in the woman’s hair!

A polarizing filter can saturate hair color.

The only down side that I can think of is that objects with reduced reflections tend to flatten a bit. Reflections naturally help our eyes perceive the 3D, spacial dimensions of an object. Removing these reflections sometimes has an equal result of flattening the image. I’ve zoomed into an area of the pictures above to illustrate this point. Notice below how the reflections in the woman’s hair on the left help define the curvature of her head and how it is somewhat lost in the picture to the right.

A polarizing filter can also flatten shapes.

Though, I’ll take the saturated colors over the curvature 98% of the time!