Why Circular Polarizers Still Matter

A high quality circular polarizer is still one of the most important accessories for any photographer’s bag. And the new Sigma Weather-Resistant Circular Polarizers offer incredible performance, weather-tough design, and a fantastically upgraded case with grip arcs that keep the filters from rattling around in the bag. wr-cpl-58mm_01 The advances in digital capture and advanced RAW processing have rendered many classic filter types less crucial, if not outright obselete; the look and feel of warming filters, and graduated density filters, for example, are easily and quickly replicated—and in many cases bested—by what is now available during RAW processing and image toning.

An afternoon sunshower created a lot of glare on the surface of the pedestrian mall in Somerville, NJ. Adding a circular polarizer (right), and adjusting the angle helped to tame the harsh surface glare. 1/320 F9 ISO 320, Canon Rebel T3i and Sigma 17-70mm F2.8-4.0 Contemporary with Sigma 72mm Weather Resistant Circular Polarizer added for right image. Exposures balanced in Adobe Camera RAW from CR2 files.

But the same can not be said of circular polarizers, which limit and constrict the angles of light reaching the image sensor. This filter can minimize unwanted reflections on shiny surfaces, make skies more rich in color and give clouds greater presence, and in general make many images in many different situations pop from the screen or page in more dramatic fashion.  And of course, the better the image quality of the RAW file to start with, the better the tonal adjustments made during toning and processing will be. This is why circular polarizers still matter.

Light reflecting off complex surfaces can be tamed, but might not be able to be completely eliminated. Here, the Circular Polarizer was adjusted to cut the reflections as much as possible on the side of the car facing the camera. You can still see some reflections on the hood, bumper and glass in the second shot. But cleaning up the reflections shown on the side of the car in the first image in post-processing would take a lot of time an patience! 1/320 F5 ISO 100, Canon Rebel T3i with Sigma 17-70mm F2.8-4.0 DC HSM OS |C at 17mm.

Circular polarizer filters thread onto the front of camera lenses, and feature a rotating ring to adjust the angle of the filter’s light-passing axis in relation to the light sources in the image. As the polarizer filter is rotated, you can visually see the effects through the viewfinder or LCD screen. When the angle of the polarizer is at maximum to the direction of the light, the effect will be most pronounced, as will the exposure impact. If you are in a program mode, you may notice the exposure values change and slow by a full stop or more. If you are in manual, you will notice the metering changing.

Adjusting the circular polarizer filter can increase or decrease the effect on the image. The top image shows the maximum polarization effect on the clouds and sky, why the lower shows a lesser effect. Rebel T3i and Sigma 18-35mm F1.8 DC HSM | A at 18mm. Both shots 1/1250 F5.6 ISO 100.

Depending on the scene, you may not need to adjust to maximum polarization; and as you rotate the filter, you may notice the polarizer is affecting different image elements, cutting the glare more off one major reflective surface, but increasing on another surface at a different angle to the sensor.  And while a polarizer is very helpful for cutting through or minimizing reflections on some surfaces, there are times when letting a major surface in the image reflect—the top of a still pond, for example, may be more aesthetically pleasing that seeing through to the pond bottom. But if you’ve got a circular polarizer with you, the choice is yours!

The Somerset County Courthouse is reflected in the door of V Lounge, across the street, part of a “found letters” project for a local art project I’m working on. By tweaking the angle of the polarizer and the lens itself to bounce off the glass, I was able to frame the courthouse and manage the effect of the reflection on the glass panel. I chose the lower version for my project. Both photos 1/400 F5.6 ISO 400 on the Reb T3i with the 18-35mm F1.8 Art lens.

When I’m outdoors making photos, there’s almost always a circular polarizer with me. If I don’t want or need it for a particular shot, it is easy enough to rotate to minimize the effects, or quickly remove from the lens completely. But for the small size in the camera bag, and big impact on image quality, these filters are always well worth packing along.

A quick twist of a 46mm circular polarizer filter attached to the 30mm F2.8 lens of the dp2 Quattro cuts the reflections and glare of the water below the fall. Which do you prefer? Both shots 1/20 F8.0 ISO 100.

Some photographers may choose to buy a dedicated polarizer for each different filter thread diameter on their lenses, 77mm, 72mm, 67mm, for example; but stepping rings are also a great way to pair a circular polarizer with several lenses with different diameter lens threads.  When going this route, the circular polarizer that matches to your biggest diameter lens threads should be bought, with stepping rings to match the diameters of the other lenses. For example, my 77mm Sigma WR-Circular Polarizer fits my 50mm F1.4 DG HSM | Art lens natively, and it fits onto my 18-35mm F1.8 DC HSM | Art and 17-70mm F2.8-4.0 DC HSM OS | Contemporary with a 72mm>77mm stepping ring.

This Victorian Inn on Ocean Ave in Cape May, NJ just jumps out from the blue sky in the morning light, as captured through the Sigma dp2 Quattro with a Sigma circular polarizer attached at 1/500 F5.6 at ISO 100. I adjusted the polarizer to ensure the deepest blue sky colors and bracketed exposures to strike the best balance between the sky and the delicate highlight tones in the all-white design of the Inn. Without a polarizer, this shot wouldn’t be nearly as stunning in its tonality and contrast.

Graduated Neutral Density filter? I’ll do that in post, or via HDRI or layers masking for very complex contrast edges. Warming filter? I’ll set a custom white balance in-camera, or do it in Adobe Camera Raw! Cut glare, tame reflections, and make dramatic eye-popping clouds? I’m packing a Sigma WR-Circular Polarizer to make it the best in-camera before making it even stronger in processing!

Got any questions about Polarizer Filters? Let us know!

Sigma has recently relaunched the full line of Weather-Resistant Circular Polarizers, Weather Resistant UV and Protector Filters under the strict guidelines and standards of the Sigma Global Vision.   Learn more.

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