A polarizing filter (also called a pol-filter) is one of the most important tools when you photograph landscapes, or generally outdoors. It is typically the first filter a landscape photographer buys to enhance his images – because it brings life and contrast to the picture. In this article you will get detailed information about polarizing filters, what they do, why they are important and why you should use one for landscape photography.

Why use a polarizing filter?

The biggest frustration when photographing landscapes is caused by something that is not there: the Colors. Sunlight is reflected by the atmosphere and objects in the landscape before it finds its way into your camera. This circumstance makes your photos seem bland and lifeless. You can compensate such reflections very easily with a polarizing filter. First you mount the filter on the front of your lens. Then you turn it to a certain angle. The filter now takes most of the reflected light out of the scene, which immediately improves your photos because there is now more saturation and contrast. When photographing distant objects, such as mountains or panoramas, a filter can also attenuate atmospheric haze.

The Effect

You may have wondered how some photographers get such rich colors in their pictures. Especially with the sky, the leaf canopy of a forest or distant objects this can be difficult. Here you have the answer: With a polarization filter. Of course you can also enhance the colors in post-processing, but the effect of a polarizing filter cannot be fully imitated even with the best image editing programs. Especially when it comes to reducing reflected light, lens flare or haze, a proper filter for landscape photography is simply indispensable.

The Application

Most lenses have a filter thread at the front, onto which you can screw a suitable filter. A so-called circular polarizing filter can be mounted on such lenses. Such a system is very easy to use. You can turn it either clockwise or counterclockwise – similar to the focus ring of the lens when focusing manually. Turning it increases or decreases the polarization effect. The position of the sun has a great influence on the polarization, so it is important to know that both the time of day and the season affect the strength of the effect.

Maximum Polarization

The maximum degree of polarization lies in a circular band at a 90° angle to the sun. So it is relatively easy to determine where the sky will appear darkest in your photos. There is a little trick to it: Form a pistol with thumb and index finger and point it at the sun. Now turn your thumb clockwise or anticlockwise while your index finger continues to point at the sun. The part of the sky to which your thumb is now pointing will have the highest degree of polarization because it is at right angles to the sun. So when the sun is directly above you just before the zenith, the sky is polarized horizontally. Thus it appears more or less evenly in all directions.

But when the sun is closer to the horizon, like at sunrise or sunset, the sky is mainly polarized vertically. This can cause problems when you photograph landscapes with a wide-angle lens. In this way the more polarized areas of the sky become visible in the image detail. If the sun rises in the left half of the image, it is clear that the right half is getting darker. Because there is the highest degree of polarization. You are often confronted with such problems when photographing landscapes during the golden hour. Then you have to be careful with the polarizing filter, especially in combination with wide angle lenses. A telephoto lens could help here because it can concentrate on a smaller area and thus hide the uneven sky.

Avoid color gradients with polarizing filters

Recently I wanted to photograph a large hot spring and did not have an ultra wide angle lens with me. So I had to shoot a panorama with a 24 mm focal length that is composed of several vertical images. Once I had assembled the panorama in Lightroom, I suddenly noticed a problem with the polarization in the sky. It was clearly visible where the maximum degree of polarization occurs, namely exactly in the middle. In comparison, the sky was much brighter on the left and right. This was because the sun rose in the right half of the picture, so the darkest part of the sky is vertical.

Such an “irregular” sky can cause difficulties in post-processing, so you should watch out for polarizing filters when you take photos with them at sunrise or sunset – especially if you use a wide-angle lens. In many cases it helps to take less sky in the photo or to turn the polarizing filter to reduce this unwanted effect. If zooming in or less sky is not an option, it is better to leave out the polarization filter completely. Then you will certainly have no problems with gradients in the sky.

Dealing with unnaturally dark sky

If your camera is pointed at the part of the sky with the highest degree of polarization and the circular polarizing filter is also at its strongest point, the sky may appear unnaturally dark, which looks pretty fake. You can counteract this by turning the polarizing filter, this weakens the effect. This makes the sky brighter and reduces the risk of a color gradient.

In the picture below I have adjusted the filter to maximum polarization. This has resulted in an unnaturally dark sky and a color gradient pattern. To solve the problem, I just had to turn the filter a little bit until the sky became brighter again. A small twist fixed everything without having to remove the polarizing filter.

Polarizing filters remove reflections

One of the main reasons why photographers use polarizing filters is to remove reflections. Reflections are everywhere and often occur in nature. Besides the usual reflections in ponds, lakes or windows, light reflections can also be caused by vegetation or rocks around waterfalls. In such situations a polarizing filter helps enormously to block the reflection. It also gives the image more contrast and color saturation. Look at the picture below:

As you can see, the water on the first photo reflects strongly. With the filter you can remove the reflection in the pond so that the water is hardly visible anymore. The color will also change. You can’t create such effects with image editing software.

Haze and Contrast Reduction

I often have to struggle with haze when taking pictures. For this reason I always carry a polarizing filter with me. For the landscape photographer among us, haze is not new and such a filter also helps later in image editing. In combination with the software’s contrast tools, we can virtually double the “evaporation”. A little haze is no problem in post-production, but when it’s thicker, a polarizing filter is really helpful.

Polarizing filters improve the colors

A polarizing filter can also be invaluable for photographing waterfalls and foliage. The picture below would have looked completely different without the filter.

When you photograph waterfalls, a lot of light is reflected by the wet rocks and vegetation. Polarization makes a huge difference in such situations. It not only attenuates reflections, but also gives the image a more beautiful tone and contrast.

Disadvantages of a polarization Filter

Unfortunately, polarizing filters not only have advantages. Here are a few things you should consider:

• Polarized filters can ruin your sky. As mentioned above, a filter in combination with a wide-angle lens can cause the gradient problem during a sunrise or sunset. The same applies to panoramas. You have to be especially careful with these because the gradient effect is very difficult to correct in post-production.

• Setting up and using polarization filters takes time. If you have a filter on when you take a picture, you have to concentrate a bit more on the actual process of taking the picture. Circular polarizing filters often need to be adjusted and if you move around a lot, a small rotation is needed before each image. The effect changes a lot depending on the position of the sun or the orientation of the camera. It is also sometimes difficult to see the change through the viewfinder at all – especially with cameras with a small viewfinder.

• Polarizing filters steal light from you! A really big disadvantage of such filters is that they block some of the light that is supposed to fall through your lens. Not all filters are the same, but in general you should expect a difference of 2-3 f-stops. High quality parts block only little light, about 1-1.5 stops. However, cheaper variants can lead to a difference of up to 3 f-stops, which is quite a lot. For this reason you should only use polarizing filters when you really need them.

• High-quality filters are expensive. Depending on diameter, glass quality, coating and brand, high-end filters can be quite expensive. If you then need a different size for each lens, the wallet becomes even lighter. My recommendation here would be that you buy only one size (the largest) and use adapter rings for the other lenses. So you can use the same filter for all lenses and save money. This way you lose time during assembly, but you have a few hundred francs more left over for other things.

• Polarizing filters can cause artifacts or flares (light reflections). A filter is another piece of glass in front of your lens and increases the risk of artifacts and light reflections – Lens Flare. Especially with cheap filters this happens frequently. You must also make sure that both lens and filter are clean, because dust or other particles can also be a reason for flares. This in turn leads to reduced contrast and loss of image quality.

• Circular polarizing filters can cause vignetting. With wide-angle lenses, pronounced vignetting may occur at the edges of the image. To avoid this, I recommend that you do not superimpose several filters. Buy only “slim” or “nano” type filters, they are particularly thin and rarely cause vignetting. But you probably won’t be able to get the lens cap on it.

Summary

A polarizing filter belongs in every camera backpack. Once again, this applies especially to landscape photographers. The filter not only makes for a more beautiful sky, it is also a versatile tool that removes reflections and haze and gives a color and contrast boost to an image. But it would be wrong to leave the part always on the lens, because then less light (1-3 f-stops) comes into the camera. In addition, the filter on a wide-angle lens can lead to unwanted gradient effects in the sky. Circular polarizing filters of high quality are expensive and need getting used to. Nevertheless, their advantages clearly outweigh the disadvantages.