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Circular polarizing filter

How and when to use lens filters

While filters are used less than in the film days, we still carry two types of filters in our camera bags when photographing nature—neutral density (ND) filters and circular polarizing filters. Skip to the end of this article if you are looking for filter purchase recommendations.

Neutral density filters

Neutral density (ND) filters are a type of filter that reduces the amount of light entering the camera. The “neutral” in the name indicates that the colors of the image aren’t changed. Think of them like sunglasses for your camera.

Using ND filters, photographers can achieve creative effects using different exposure settings by reducing the amount of incoming light to the camera.

Slow shutter speed

Because ND filters reduce the amount of incoming light, photographers can capture a scene using slow shutter speeds. Very slow shutter speeds allow you to create images of water that are silky smooth, blurring waves, ripples, or waterfalls.

ND filters can also blur the motion of fast-moving clouds, creating a dreamy effect in the sky.

Mt. Shuksan at Picture LakeMt. Shuksan at Picture Lake
Ripples on water photographed without an ND filter (1/50 second) and with an ND filter (30 seconds).
Shilshole Marina at SunsetShilshole Marina at Sunset
Ripples on water photographed without an ND filter (1/10 second) and with an ND filter (6 seconds).
WestRock Paper & Pulp Mill
ND filter used for slow shutter speed, smearing the exhaust from a paper mill.

Video

In videography, some motion blur is desired to give the video a cinematic look, and lighting conditions may require neutral density filters.

Cinematographers often want to choose an aperture and depth of field for a particular scene. For a shallow depth-of-field, this means shooting with the lens wide open at f/4 or f/2.8, allowing lots of light to reach the sensor.

For brightly lit scenes, particularly outdoors, after lowering ISO sensitivity to its lowest setting, the only way to achieve proper exposure would be to make the shutter speed faster. But if the shutter speed is too fast, the resulting video will have an unnatural-looking motion blur or lack thereof.

By adding a neutral density filter to the lens, the camera operator reduces the light reaching the sensor and can lower the shutter speed to achieve the desired motion blur while maintaining the desired aperture.

ND filter strength

The strength of a neutral density filter is measured in stops of light, which refers to the amount of light that a filter blocks. For example, a 1-stop ND filter would allow half of the light through. A 3-stop filter would allow 12.5% of the light through (0.5 x 0.5 x 0.5 = 12.5%)

Landscape photographers will find that rapidly changing light around sunrise and sunset requires changes in the strength of ND filters to match the scene’s brightness. Filters can also be stacked on top of one another when more darkening is needed.

If you want to purchase just one ND filter, a 6-stop would be most helpful. For a complete set of ND filters, we recommend carrying a 3-stop, 6-stop, and 10-stop filter to cover all lighting situations.

Other types of ND filters

Graduated neutral density filters

A graduated neutral density filter has a transition from light to dark built into the filter, providing a balanced exposure between a bright sky and a relatively dark foreground. Landscape photographers will line up the transition line of the filter with the transition between the sky and the land.

Using graduated neutral density filters can be tricky and has become less popular because the dynamic range of modern cameras is substantial, and post-processing software can achieve similar effects. Also, the straight transition line on the filter is not helpful when you have an irregularly shaped transition between the sky and the land, like a mountain range.

Variable neutral density filters

A variable neutral density filter allows the photographer to change the strength of the filter by rotating it. While it sounds convenient to carry a single neutral density filter that covers a range of darkness, these variable filters are known to have issues like color shifts, vignetting, and visible cross-hatched patterns.


Circular polarizing filter

Circular polarizers are a type of filter that helps to cut reflections and glare, providing more color and contrast to certain scenes. The physics behind these filters can be pretty technical, but you can learn more about it here. In simple terms, the circular polarizer allows you to block particular directions of polarized light. Many sunglasses use this same technology to reduce glare.

Unlike other lens filters, a circular polarizer has a ring that you can spin 360 degrees. Rotating the filter will remove more or less polarized light, increasing or decreasing the filter’s effect depending on the rotation.

With digital photography, circular polarizing filters find less use than in the days of film. You can often achieve similar color and contrast effects using post-processing software. However, certain scenes benefit tremendously from a circular polarizing filter, with effects that software cannot replicate.

When to use a circular polarizing filter

Water reflections

One of the most obvious times to try a polarizer is when photographing water, like a river or the surface of a lake. A circular polarizer can reduce or eliminate the glare and reflection on the water’s surface.

Silver Falls in Mt. Rainier National ParkSilver Falls in Mt. Rainier National Park
Waterfall photographed with and without a circular polarizing filter. Notice the dramatic blue color of the river is revealed, and the foliage colors become more saturated.
Wet surfaces and foliage

Wet rocks or leaves can have significant reflections that hide their underlying color and detail. Using a circular polarizing filter on scenes like this dramatically reduces the reflections from these surfaces, revealing their actual color.

Sculpted red walls of Avalanche Gorge in Glacier National ParkSculpted red walls of Avalanche Gorge in Glacier National Park
Wet rocks photographed with and without a circular polarizing filter. Notice the filter removes most of the bright glare on the rocks.
Hoh RainforestHoh Rainforest
Forest photographed with and without a circular polarizing filter. The bright, bluish reflections on the ferns are removed, revealing the green color of the foliage.
Clouds and atmospheric haze

Polarizing filters can darken skies and brighten clouds. They can also cut through the glare of atmospheric haze. While the effects can sometimes be dramatic, be cautious about how much of the effect to apply, as it can sometimes leave the sky looking unnatural.

Black & white

Black and white photos allow much more creative freedom when adjusting brightness. A polarizing filter can be helpful to darken a sky or enhance clouds when shooting for black and white.

Determine when to use a circular polarizing filter

What impact will a circular polarizer have on your scene? The easiest method is to remove the filter from your bag and hold it up to your eye. Rotate the filter to see how it impacts your scene’s glare, reflections, color, and contrast before you put it on the camera. For some scenes, the effect will be subtle or non-existent. For other scenes, the effect can be pretty dramatic.

After you put the polarizing filter on your camera, preview your image and experiment with the rotation of the filter before clicking the shutter.

When to avoid circular polarizing filters

  • Wide-angle lenses – Wide-angle lenses can show uneven polarization effects, particularly in the sky, with blotches of different brightness that are unattractive and impossible to remove.
  • The angle of the sun – Polarizers work best when the direction of the sunlight is at a 90-degree angle to the camera. When the sun is directly behind or in front of you, the effect of a circular polarizing filter is minimal.
  • Desired reflections – Sometimes, a reflection is desired as part of your composition. Removing a reflection with a polarizer will make the image look dull. If you still want to use a polarizer to enhance the sky, take another picture without the polarizer to capture the desired reflection. Then, merge the images during post-processing.

Types of lens filters

Lens filters come in a variety of shapes. It is essential to match your filter or adapter sizes to your lens.

  1. Circular screw-in filters – Circular screw-in filters are the most popular filter type. These filters mount directly by screwing them into the filter thread on the front of your lens. When you purchase a circular screw-in filter, match the filter size to the size of the filter thread of your lens. If you have lenses with varying filter thread sizes, purchase the filter size for your largest lens and use a step-down ring to accommodate your smaller lenses. (e.g., Buy an 82mm filter with an 82–to–72mm step-down ring.) These screw-in filters can sometimes get jammed; carrying an inexpensive filter wrench to remove them is helpful.
  2. Magnetic filters – When you use filters often, screwing them onto your lens is tedious and can be problematic in cold weather. Some filter sets are magnetic. You attach a single adapter ring to your lens and then attach the filters to that adapter with magnets. These magnetic systems allow you to add and remove filters quickly.
  3. Rectangular or square filters – Some filter systems have square or rectangular filters. They attach to the front of your lens using a unique filter holder. Because the filters are larger than the front element of your lens, they can be used on various lens sizes. Most graduated neutral density filters are rectangular.
  4. Drop-in filters – On lenses with large front elements, often, there is a small drop-in compartment at the back of the lens. Adding a small filter at the back of the lens is easier and less expensive than using large filters on the front.

Filter purchase recommendations

If you are planning a photography trip and need filter recommendations, please get in touch with us.

Quality differences make some filters better than others. High-quality filters are durable and introduce little to no color cast in your images. The darker the filter, the more likely it is that it has a color cast. We currently use and recommend filters from Breakthrough Photography and Kase. Both are durable, with good color neutrality.

For circular screw-in filters: Breakthrough Photography

For magnetic filter systems: Kase Filters

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