Polarizer
160 Linear Polarizer
164 Circular Polarizer
If you do not have a polarizer, stop reading this and get one! I use a polarizer on almost every shot with a blue sky. Without a polarizer, blue skies appear a tepid, light blue on film; with a polarizer filter, they come out in a rich, deep color. The filter works by cutting out reflected glare and it's also useful for water (lakes, ponds), window glass, and tree leaves. A polarizer is more expensive than most other filters but worth the investment.
Regardless of the type of shooting you do, a polarizer is the most useful and versatile filter you can own. It's a very visual filter with which to work: As you rotate it in its mount, the effects are immediately noticeable. A polarizing filter can deepen the color and contrast in a sky (the most intense effects are always 90° from the sun or light source), eliminate glare from wet or reflective surfaces and cut through atmospheric haze to increase clarity and contrast in a scene. Since the effect of a polarizer is most pronounced when it is used perpendicular to the light source (the sun usually), try this trick... Make an "L" with your thumb and forefinger. Point your forefinger at the sun and your thumb will point in the direction that the polarizer will have its greatest effect. You can rotate your thumb around the axis of your forefinger, pointing the lens in any of these directions will let you take full advantage of the polarizers capabilities. Polarizers have little or no effect when they are used in the same direction as the light source.
Polarizers come in two varieties: Linear 160 and Circular 164. Each has the same effect visually; the difference is just in the way they polarize the light passing through. If you own an auto focus or auto-exposure camera (basically any modern camera), use a 164 Circular polarizer, which won't interfere with its automatic functions. Digital cameras in general do not have reflection mirrors, and, as a result, can use both (linear or circular) polarizers.
LINEAR
Produces deeper colored blue skies, which at the same time creates a striking contrast with white clouds. Minimizes light reflections from glass and water Reduces glare from non-metallic surfaces. Provides a general color saturation to both cool and warm tones. Can be used in extremely bright light situations to reduce the amount of light entering the camera; this enables more selective depth of field control. Manufactured in self-rotating and drop-in formats. Note: using a Linear Polarizer on an auto focus camera with a beam-splitting meter will result in under-exposure of approximately 2-3 f:stops. Light is polarized by both the filter and the beam-splitting meter which results in double polarization. However, Linear Polarizers can be used with both non-auto focus and auto focus video cameras.
Light Loss: 2 f:stops
CIRCULAR POLARIZER
Provides the same filter effects as a Linear Polarizer, but is designed to work with auto focus cameras with beam splitting metering. The Circular Polarizer has linear polarizer construction plus a built-in "Wave Retardant" to ensure proper exposure. The linear element polarizes the light, and the wave retardant de-polarizes it, and then the beam-splitting meter polarizes the light again for proper exposure. The use of a Linear Polarizer with a beam-splitting meter will result in underexposure. Also used in video for video assist. (video tap).
Light Loss: 2 f:stops
What is the difference between the Polarizer and the circular polarizer ?
A circular has an additional quarter-wave plate or scrambler behind the (still linear) polarizing foil. Although not scientifically correct, it more or less restores the natural 50/50 vertical/horizontal balance of polarization, without affecting the initial pictorial result.
Only by restoring this natural balance it will allow the light metering and AF sensors to work properly, as they use polarizing beam splitters. With a linear filter, you would risk a cross-polarizing effect, ie a black-out. Bad for both light metering and AF.
In spite of what most people will tell you: the main reason to buy a circular polarizer is *not* the AF sensor, but the light metering system. You can *see* when AF goes haywire (it won't shift focus, it just has more difficulty to lock on), but you can only guess what happens with your light meter!
Actually, the first circulars were required long before AF existed, and are still required for non-AF cameras today (Rollei 600x series is a nice example).
POLARIZER TIPS
TIP #1: How much a polarizer filter will darken a sky depends on the type of sky and your shooting angle in relation to the sun.
TIP #2: On a sunny day, position your shoulder towards the sun and your subject at a right angle to your shoulder. When the sun is high in the sky, maximum polarization will result along the horizon. When the sun is low in the sky, maximum polarization will result in all areas in front of and behind you.
TIP #3: A polarizer has very little effect when used under a gray, overcast sky.
TIP #4: Remove any protective lens filters when using a polarizer.
TIP #5: Use a polarizing filter indoors only for reducing relections and glare. Any color saturation will be minimal. Remember, a polarizer filter will effectively reduce your lens aperture by up to 2 f:stops.
TIP #6: Use a polarizer filter to control depth of field. This is similar to using a Neutral Density filter, except that the Neutral Density will render "neutral" colors, while the polarizer saturates colors. Neutral Density filters are available in greater light reducing densities than polarizers.
TIP #7: To distinguish a Circular Polarizer from a Linear Polarizer, turn the filter backwards and look through it into a mirror. If the filter image in the mirror is black, you have a circular polarizer. If the image is clear, you have a linear polarizer.
Tip # 8: A Polarizer tends to cool down the image. I find adding a Warm filter will restore warmth and a more natural image.
Jim Dees
No Polarizer
164 Polarizer and 027 Warm
Mt. Washington, New Hampshire
Photo by Ken R Sheide
Cokin Circular Polarizer #164
"A scene I encountered in the hills of Terceira on an overcast day. I liked the view so much that I came back on a sunny day just to take this picture!"
Ken R Sheide
Photos by Dr. Ching-Kuang Shene
Without a polarizer
With a polarizer
Without a polarizer With a polarizer
Also look at these pages for more examples of what a Polarizer can do
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