photography-101:-using-a-polarizing-filter:

A Simple Tool That Can Produce Amazing Results

Photo of pink water lilies and lily pads with all the glare removed by the polarizer. AFTER: Waterlilies and pads shot with polarizing filter.
AFTER: Waterlilies and pads shot with polarizing filter.

By F.M. Kearney

Back in the days of film, I used to carry a complete assortment of filters in my camera bag. I had warming filters, cooling filters, neutral density filters, graduated neutral density filters, special effect filters and, of course, a polarizing filter. The digital age had made life much easier. Most of these filter effects can now be applied in post with much greater precision and in varying degrees of intensity. Not having to carry so many filters is a definite plus, but there are some filter effects that can’t be created digitally… yet.

Urban Nature is a new feature of NANPA’s blog, a series of articles created to address the issues of nature photographers living in urban areas, with little or no access to conventional, natural environments. It will focus on topics ranging from finding subjects to finding inspiration. Also, in an effort to attract more beginners into the field, it will attempt to demystify the art of photography in general.

One such filter is the polarizing filter. Unlike other filters that are simply placed on a lens and forgotten about, a polarizing filter is not a “set it and forget it” type of filter. It’s comprised of a layer of synthetic plastic sandwiched between two glass plates. By rotating the front plate, the polarized (or reflective) light in the scene is removed – giving you complete control over how much or how little is eliminated. The remaining light is more diffuse – resulting in a more color saturated image. If you change your orientation, i.e., from horizontal to vertical, you must re-rotate the filter in order to get the same effect.

Two types of polarizing filters

There are two types of polarizing filters: circular and linear. Circular polarizers are more common because they’re designed to work with autofocus and auto-metering systems. Linear polarizers, on the other hand, are more suited for video cameras and manual-focus lenses. The elimination of the polarized light entering the lens causes an overall reduction of about 2-stops of light. Therefore, a polarizing filter should not be kept on the lens at all times like a skylight or UV filter, but used only when absolutely needed.

Most photographers are well-aware of the effects of a polarizing filter on a blue sky. Some might believe that it makes a blue sky “bluer,” but in actuality, it’s simply removing the polarized light – making it appear bluer. The before and after images below illustrate a typical scene where a polarizing filter really shines. I shot them on a sunny day with a blue sky and large, white puffy clouds in New York’s Central Park at The Lake (yes, that’s the actual name of this lake). With the polarized light removed, the clouds popped and the true colors of the scene were brought forth – improving the overall tone of the image. As I mentioned earlier, the strength of the filter’s effect is determined by how much you rotate its front plate. In scenes like this, it’s also determined by the position of the light source – in this case, the sun. To remove the maximum amount of polarized light, the sun should be at a 90-degree angle to your position – that’s to your left or right. If the sun is behind you, or if you’re facing the sun, the filter will have no effect. It should also be noted that the filter may not produce the best results when used with super-wide-angle lenses. The effect may not extend all the way to edges of the frame – resulting in an unevenly colored sky.

Two images of a lake in Central Park. In the foreground is foliage and in the background are high rise buildings under a cloudy sky. Left: The Lake without polarizing filter.     Right: The Lake with polarizing filter. The view with polarizer has richer colors.
Left: The Lake without polarizing filter. Right: The Lake with polarizing filter.

Managing reflections and glare

While enhancing blue skies may be the most common use of a polarizing filter, it’s certainly not the only one. Reflective surfaces are just about everywhere. Our eyes are great at acclimatizing to it and helping us to see through the chaos. But, when seen in a photo, it becomes much more obvious and distracting. The before and after photos below clearly show the benefit of using a polarizing filter to remove harsh glare. In the photo taken without the polarizer, it’s hard to even see the branch in the foreground through all the clutter. But the image becomes a lot “cleaner” after all the reflections are removed – making the branch a bit more visible.

Photo of green leaves of a bush. BEFORE: Branch is lost amongst reflections without polarizing filter
BEFORE: Branch is lost amongst reflections without polarizing filter
Photo of green leaves of a bush. AFTER: Branch stands out better with reflections removed by polarizing filter
AFTER: Branch stands out better with reflections removed by polarizing filter.

More so than the sky and foliage, water is probably the most reflective surface you will encounter. If you’ve ever tried to photograph waterlilies, you have undoubtedly encountered this problem. Below are before and after images showing the dramatic effects a polarizing filter can have in a situation like this. The reflection coming off the water, and especially the lily pads, is absolutely blinding in the before shot. Once the filter is applied and the glare is removed, the photo is improved so much that it almost looks like a totally different image. No fancy digital effects were used. All it took was the simple application of the filter.

Photo of pink water lilies and lily pads with a lot of glare. BEFORE: Waterlilies and pads shot without polarizing filter
BEFORE: Waterlilies and pads shot without polarizing filter
Photo of pink water lilies and lily pads with all the glare removed by the polarizer. AFTER: Waterlilies and pads shot with polarizing filter.
AFTER: Waterlilies and pads shot with polarizing filter.

I don’t think anyone would disagree that the filter made a definite improvement to the image above. However, that may not always be the case in every situation. The image below was taken without a polarizing filter. Try not to get into a mindset of believing that all reflections are bad and must be completely eliminated at all costs. There are reflections on the lily pads, but they’re nowhere near as garish and off-putting as they are in the example above. Besides, I kind of like how the little puddles atop the pads are visible. Also, the reflection of the blue sky on the water adds another color element to the scene.

A white waterlilies without polarizer. Reflections of blue sky and white clouds are seen in the water. BEFORE: Reflections are retained without polarizing filter
BEFORE: Reflections are retained without polarizing filter

The polarizing filter removes all of that in the image below. It also turned the water jet-black – revealing the unsightly stems beneath the surface. Although it slightly improved the color of the lily pads, it rendered the little puddles invisible – which, I felt, added more interest to the before shot. Lastly, since the waterlilies are white, the filter’s effect on them was negligible.

A photo of white waterlilies with polarizer. The water has turned black and lily stems and roots are visible. AFTER: Reflections are removed with polarizing filter. Is this an improvement?
AFTER: Reflections are removed with polarizing filter. Is this an improvement?

Of course, all of this is subjective. Others may look at the after shot and think that it’s a million times better than the before image. The beauty of a polarizing filter is that it’s completely customizable – almost like a digital effect. As I mentioned at the beginning of this article, you have total control over the intensity of its effect. If you don’t want the water to turn jet-black, simply rotate the front plate until you reach an effect more suitable to your vision.

All of the photos in this article were shot on a sunny day, however, a polarizing filter can also be beneficial on an overcast day as well. A cloudy, white sky can be just as reflective on shiny surfaces as a clear blue sky. Although its effect may not be quite as dramatic, the filter can definitely make an improvement to photos shot under these conditions.

The effects of a polarizing filter are completely dependent on the strength and/or position of the light source. Before I go through the trouble of attaching it to my lens, I’ll often hold it up to my eye and rotate it. If it has little or no effect on the scene, I’ll know immediately that I can forgo its use. In any event, this amazing little tool is something you should always carry in your camera bag… at least until digital technology figures out a way to mimic its effect.

NOTE: The polarizing filter was actually on the lens for both the before and after photos. I simply rotated it to its weakest position for the before shots. This allowed me to shoot both images within seconds of each other before the ambient light changed.

Photo of F.M. KearneyF.M. Kearney began his career as a photojournalist for a variety of local New York City newspapers. It was an exciting profession, which allowed him to cover everything from famous celebrities to ride-alongs with NYPD and FDNY. He now specializes in nature and urban landscapes. To view more of his work, visit www.starlitecollection.com. He can be contacted at starcollec@aol.com, or followed on Facebook (@fmkearneyphotos) and/or Twitter (@fmkearneyphoto).

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