John Grogan | A Practical Look at Polarizing Filters

A Practical Look at Polarizing Filters

May 05, 2017  •  Leave a Comment

I get a lot of questions regarding, what type of polarizer to use? Meaning should I get a circular polarizer or a linear polarizer?

On the surface one would say a circular polarizer is used on all modern DSLR or SLR cameras if you are still using film. For the sake of this subject I need to assume two things, this is not a technical conversation and I assume we all know how a polarizer works and why use them.

The need for circular vs linear polarizers seems to stem from the way auto focus and the auto metering functions of the camera body share light coming thru the lens and in this case the filter. The idea is because of the reduced amount of light can cause the camera to misjudge the light and cause the metering system to give you the wrong exposure and or focus.

Another issue is multi coating used on lenses and filters. It is difficult to find quality filters that use multicoating. In most cases, they are expensive and hard to find. A circular polarizer is simply a linear polarizer with an extra layer or coating affecting the way light is transmitted to the sensors in your camera.

Now those are the issues, but in application what is the net result. Let’s look at price. I compared a Hoya 77mm circular to a Hoya 77mm linear polarizer. Using B&H Photo for pricing, I found the linear to be $46.99 and the circular polarizer was $93.90 with variations of circular polarizers up to $199.00. But that’s a look at price and we all know price is not a final factor.

In practical uses in both a hand-held meter and the built-in meter, the polarizer is at or below 1/3 stop difference in the error factor. On some cameras, a third stop is not enough variance to affect the image. In most prosumer and pro cameras, you could see a difference, but in those situations the photographer brackets taking in account of the filter characteristics. In my personal practice, most all assignments and personal projects are shot on manual exposure so this issue is not a problem. Most of the reviews and comments I found in researching this subject is that people for the most part cannot tell the difference.

Conclusion. If you are starting out in photography go ahead and get the circular, the idea always is to get the best product you can afford. If you’re like me, and already have the linear filter continue to use it but understand the differences. In fact, I have both and I really use them without noticing the difference. But above all, knowledge is the key.

Why and how to use to polarizer? Sounds like a subject for later on …


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