A major difference in image results between a novice photographer and a pro is something that doesn’t really have much to do with either’s talent, though it is an issue of experience. It is the use of a simple, and for most, affordable piece of equipment; a CP, or Circular Polarizing Filter.

For a ¹scientifically technical description of how a CP filter works, you are welcome to do some simple research on the web. This article will avoid the science and illuminate the application.

What does the CP Filter do?

A common application of the CP filter is noticed in photographs and video footage of scenes that include blue sky. With the naked eye, a lot of sunny days seem more hazy than others, presenting a white tinted, or washed out sky. Usually, the white is from sunlight, and Earth reflected sunlight illuminating the haze of moisture and thin white clouds in the otherwise deep blue sky. The polarizing filter realigns the light rays to hide the reflection caused by the sky born haze. Removing the reflection of light off the thin have allows one to see a deeper blue sky. The same type of effect is noticed when wearing polarized sun glasses that remove reflection from the surface of a swimming pool or window reflection, like looking into a car windshield to see who is driving the car. This is one of the reasons so many law enforcement officers wear shades almost all the time. They also look cool.

 

The polarizing effect has a lot to do with the angle at which the offending light is reflecting off the shiny surface; be it clouds, water or glass. Therefore, polarizing filters don’t always work. For this reason, still photography is a much better candidate for the CP filter than a moving video shot due to the inherent mobility of video and the inherent stillness of—well–still shots.

Because, if one is following the movement of an object with a video camera, the angle of reflected light will undoubtedly change through the video shot, reducing or increasing the effectiveness of the CP filter. This would cause the effect of the sky going from deep blue to hazy white and back again, or vice versa; certainly a distracting effect. On an outdoor, daylight shot, if the camera is locked in place on the tripod so that it cannot pan or tilt, the CP filter can work wonders if used at the correct angle to the sun for a limited time.

But, in still photography there is no changing of the light angle at time of firing. The angle is fixed due to the nature of “still” photography as opposed to moving video. Thus the effectiveness of the CP filter in still over video.

I use the CP filter for almost all outdoor shooting still shooting and even some indoor.

Why use the CP Filter?

The CP filter is known to produce richer color, better flesh tone and better texture in some cases, due to the removal of offending reflected light. Deeper blue sky and darker, richer green grass are two of the more common noticeable effects. The same effects can be enjoyed without the filter, but only on days when there is extremely low humidity. The sky will be almost as deep blue as with the filter but, the grass won’t be as dark and rich, and other effects won’t follow suit either; like glare off water, in windows and the shiny faces will still be there.

Example of using a CP filter at the proper angle. Notice the deep blue color of the sky and the rich color of the greens and reds. The filter has removed most of the water reflectiveness of this shot from sky and Earthbound objects like grass, trees and fallen leaves.

Now, I’ve turned the camera about 100 degrees to my left away from the first shot’s angle, towards the sun.

No adjusting the CP filter at this angle can remove any refectiveness at all. The sky is white and washed out as are many of the colors on trees. Obviously, shooting with the sun at the wrong angle removes likelihood of good color capture anyway. Like our eyes, the camera needs to receive reflected light of true color. The CP filter simply removes glare, or white light that reflects off of surfaces and sky bound water vapor (clouds) when used at the correct angles.

A more vibrant photo is what you get when properly using this filter. It should always be handy. I have one for each of my lenses. I am just getting ready to purchase my second working camera, probably another Canon, and I will make sure to pick up two more CPs for its kit as well. There are many events I cover where I need two working and live cameras hanging on my neck. Switching out lenses and filters is not an option during these times. So, I need to have the filters on the lenses, and the lenses on the cameras ready to shoot all the time.

When not to use the CP Filter

Because the filter reduces the amount of light in the light path, there are a few applications where I will remove the lens. All portrait photography I usually start without it. I have noticed that some people sweat more than others and the CP filter will often reduce a generous portion of the reflected light from the shiny face. But, this also changes other elements’ appearance as well, so my application in this environment is limited. Backgrounds change with a reduction of light, so if I am going to need the CP filter, I make sure I conduct the entire shoot with the filter on. This keeps the background consistent.

Why use filters at all when I can just PhotoShop it later?

In case you don’t already know this, PhotoShopping is not the miracle cure for everything. PhotoShop can’t fix bad focus, over exposure, under exposure or put texture back into something that the camera and its operator failed to capture. PhotoShop can certainly minimize errors and maximize assets, but only a correct capture at the event produces truly stunning photos and video. The CP filter helps that to happen.

Best and most common application of the CP filter. How to.

The sky is the easiest to notice when shooting with a CP filter. After mounting the filter on your lens, put the sun off of your left or right shoulder, then point the camera up into the blue sky. Zoom back so you can have an obvious point of reference on the horizon. Let the focus set where ever you want; makes no difference to the filter. While viewing through your SLR viewfinder glass, turn the outside ring of the CP filter so that it turns around either way, clockwise or counter clockwise. You’ll notice that the tone of the blue sky changes from light to dark or vice versa. There is no written scientific rule on where to set the filter at this point, but I always go for the darker blue. This is where the filter is doing more of its reflective nulling work. Once you have the sky looking its darkest, slowly change your angle in reference to the sun by turning your body left or right while still looking at the sky through the viewfinder. Notice that the sky’s tone changes just as if you were still turning the filter. In this fashion you can quickly learn the best angle to setup for great looking shots using your filter.

By Stu Marks: Chicago Area Media Designer & video consultant.

¹                      http://www.ehow.com/how-does_5402629_circular-polarizing-filter-works.html
                http://en.wikipedia.org/wiki/Photographic_filter