Pop on a pair of (decent) sunglasses and not only are your eyes less strained, things just look better. The reason for this is likely the polarization effect. Colors may appear more saturated, bright blue skies can take on a deeper hue, and some pesky reflections just vanish. All of these can benefit certain photographs and make the circular polarizer filter one of the best—and most difficult—filters to use.
Exactly What Does a Polarizer Do?
It’s both simple and difficult to understand what polarizing filters accomplish. Technically, per our expert product writers, a circular polarizer “helps to reduce reflections and glare by filtering out light that has become polarized due to reflection from a non-metallic surface.” Essentially, this means it cuts down on certain types of light in a way that can benefit your imagery. More specifically, it will reduce glare and reflections, including certain haze. In real-world applications this can help eliminate reflections on glass or water, reduce some reflected light on certain subjects, or improve overall contrast in a landscape.
You may have heard of linear polarizers, in addition to the now standard circular polarizer. In practice, both filters accomplish the same goal. However, circular polarizers have an extra quarter wave-plane element that helps convert the light back into a form that is suitable for modern autofocus and auto-exposure systems. Since this tech wasn’t around years ago, early filters were fine with linear polarization, but if you are shopping today, circular is the safe bet.
Basic Polarizer Tips
How exactly do you best make use of a polarizer? That can be incredibly easy or extremely technical, depending on how you want to approach it. If you pick one up, you will notice that the front part of the filter spins and then changes the appearance of the image on your camera. You could very easily just make the adjustments, preview in the camera, and then just pick a position that looks the best. Simple and effective.
Technically, there are some things to know. Among the most important is that polarizers work best when at a 90° angle from the sun. This means that you should practically never use a polarizer facing directly toward the sun. Another reason to take off the filter for shots that include the sun is that the extra glass can result in more flaring. So, your sunsets and sunrise photos will be better off without the filter.
Another thing to keep in mind is that polarization is not likely to have a uniform appearance across your entire image. This is especially true with wide-angle lenses. Getting a deeper blue out of a sky is a very common use for a polarizer, but if you are shooting with an ultra-wide lens you may see that the sky shifts quickly from normal to dark in an unnatural way. Be careful with the way you apply it and you shouldn’t have an issue. You have control over where and how much polarization will have an impact on your photo, so you should experiment.
While using the filter, you may notice that your camera’s meter is telling you to increase your exposure. That is because polarizers generally absorb some of the light entering the lens—it is part of their job. You can expect to lose between 1-3 stops of light, depending on the exact model and brand of filter you picked. It can result in some moments where a tripod might be advisable to get your exposure just right. It also means that polarizers are not going to be great filters for low-light situations.
If you are looking for a recommendation, we chose the B+W XS-Pro Kaesemannn Circular Polarizer MRC-Nano Filter for our tests, and found it to be very reliable, though you should have good luck with plenty of brands on the market.
That should be all the basic information you need to get started with a polarizing filter, but if you have any questions, please feel free to ask in the Comments section, below.