How a polarizer filter works


The two best things about summer are clear blue skies and beautiful sparkling oceans as far as the eye can see. Unfortunately, these are also two of the most reflective things out there.

If you’re not careful, you can wind up with summer photos that have big ugly reflections and white, blown-out skies. How can you fix it? A polarizing filter for your camera, properly used, can help enhance the deep blue colour of the sky. It will also help you minimize harsh reflections from water, making your summer photos look gorgeous!

What is a Polarizing Filter?

A ‘polarizing filter’ or polarizer is a filter for your camera that controls how much polarized light you allow to enter the lens. There are two types of polarizing filter: linear polarizers and circular polarizers.

Originally photographers used linear polarizers, which blocked the light with a series of horizontal openings like venetian blinds. Eventually, advances in the way auto-focus mechanisms worked rendered linear polarizers useless. Circular polarizers were developed, designed to work with newer auto-focusing systems. They also allow you to adjust the effect by turning the ring around the filter.


How Polarizers Work

Light coming from a reflected surface is all the same wavelength. This allows the filter to eliminate reflected light on that specific wavelength, making the reflections fainter. This is useful if you’re taking a photo of someone wearing sunglasses or landscape photos of the ocean.

You can also apply that same effect to the sky, but it works a bit differently. Since the light is reflecting off all the moisture in the stratosphere, you make the sky appear a deeper blue. It’ll also increase your contrast between the clouds and the sky. Polarizing filters are the filters of choice for landscape photographers.


Disadvantages of Polarizing Filters

Polarizing filters can get expensive. Where your average UV filter runs from $10-20, most polarizing filters start at $60 and go up to $150. A trick to avoid buying polarizers for each of your lenses is to buy one polarizer for the diameter of your widest lens and use cheap step-up rings for smaller lenses.

plane.jpgAnother disadvantage is that the filters are quite dark. They will force your exposure down at least one stop, making it harder for you to use a high shutter speed. This is the biggest argument against leaving them on your camera all the time.

Polarizing filters an essential tool in the landscape photographer’s toolkit. Photographers of all skill levels and fields find them useful at one time or another. In the end, it’s up to the individual photographer to decide if they want one. Just keep in mind that good use of a polarizing filter can make your summer photos really pop!


This article was written by my good friend Andrew Ferguson, who runs the Golden God blog, which is full of fabulous articles – much like Photocritic, in fact, and well worth a slot in your RSS reader. Fancy writing a guest article for Photocritic? Drop me an e-mail with an article idea!

The photo of the building is © Andrew Ferguson. The 4-up comparison of with-and-without polariser images is under creative commons, and was done by Flickr user Higashitori. All non-marked photos are © Haje Jan Kamps /