If i had a nickel for every time someone asked if they need a polarizing filter…i should change my name to Jefferson.  The thing about polarizing lenses is that you really do need them, when you need them.  I should change my name to Cryptic Jeff.  A polarizing filter is designed to do one thing very specifically and it is truly (so far) the only way to achieve the effect.  I say “so far” because software is becoming more competent every day and could, at some point in the not to distant future, replace the need for optical filtering.  The image to the left is from my recent trip to the National Street Rod Association’s annual hot rod event.  Using a polarizer is a must for an event like this.  The ability to cancel out the reflective value and allow the color of the paint to show will make a HUGE difference in the look of your image.

For a fancy description of what a polarizing filter does to the light that makes your image see this incredibly boring wikipedia article.  For those of us that cant call MIT our Alma Mater, a polarizing filter allows certain wavelengths (colors) of the visible light spectrum to come through the lens and bounces other wavelengths away.  These filters are very effective at reducing reflections and this is why polarized lenses are used in sunglasses.  Here is the tricky part though, you can purchase $10 sunglasses or $200 sunglasses and there is a major difference in how efficient the glasses are at polarizing the light.  The same holds true for lens filters.  A high quality filter (which will cost more than a few Jeffersons) is going to deliver consistent results across the entire field of view of the lens.  This is especially important when using wide angle lenses.

Wide angle lenses have a very large field of view which means the light that makes that image is collected and bent into the camera lens at a steep angle.  High quality camera lenses are built to correct for optical aberrations that occur as a result of the light being manipulated in this manner.  Low quality filters are not.  A cheap polarizing filter will not provide a consistent effect across the entire field of view of the image.  Instead you will be left with the effect in one area while the rest of the image remains unaffected.  Keep in mind a cheap polarizing filter for an average sized consumer lens can set you back about $50-70 .  Typically you will invest another 25-35% for a pro-grade filter like the B+W or Hoya HD brands.

So, while most photographers think of using polarizing filters for landscape shooting because it produces a rich blue sky with nice contrast in the clouds,  it is also minimizing unwanted reflections and glare in your scene.

The image to left is shot with exactly the same camera settings, lens, camera body, position of camera, etc as the image to the right.  The only difference is the use of a polarizing filter on the image to the right.  Note how the reflection of the sun is not completely hidden.  No polarizer will do that.  Pick your battles.  More importantly, notice how the beautiful color of the classic Corvette comes through with a properly used filter.

Both of the following images were shot with a polarizing filter, but the filter was set to different position in its rotation.  The top image was set to reduce glare on the hood of the car.  In this case the color wasnt being drastically affected by the reflection of the sky, but the reflection was extremely annoying to see.  However, notice the glare on the side of the truck to the right side of the image.  Because  these two surfaces are perpendicular to each other, you cannot polarize to reflection on both surfaces simultaneously.

The image below shows the reflection on the hood of the car but omits it on the truck.

As always, click on any image to see it larger.