Polarizer Lens Filters: How They Work and Which to Buy

A polarising filter (also spelled polarizer) is a screw-on filter that cuts glare and reflections, deepens blue skies and boosts colour saturation – effects you cannot fully recreate in editing. The most useful type is a circular polariser (CPL), which you rotate to dial in the strength. Here’s how they work and how to choose one.

Image: Without (top) and with (bottom) a CPL filter. Copyright Chris Sale

As a photographer, I’m constantly seeking ways to elevate my images and capture the world around me in a captivating way. One powerful tool in my arsenal is the polarizer lens filter – or polariser lens filter, depending on your language!

This seemingly simple piece of equipment can unlock a world of creative possibilities, enhancing landscapes, reducing glare, and boosting colour saturation in your photographs.

What is a Polarizer Lens Filter?

A polarizer lens filter is a circular glass filter that screws onto the front of your camera lens. It contains a special film that selectively filters incoming light, reducing glare and reflections from non-metallic surfaces like water, glass, and foliage.

By doing so, it produces several desirable effects:

Deeper, richer colours: By filtering out scattered light, polarizers allow for deeper penetration of colour-saturated light, resulting in more vibrant and intense colours in your photos. Imagine capturing the bluest skies, the greenest landscapes, and the most vibrant foliage, all achievable with a polarizer filter.

Reduced glare and reflections: Glare on water surfaces often creates an unwanted milky white sheen, obscuring details and distracting from the scene. Polarizers effectively remove this glare, revealing the true colours and textures beneath the surface. This effect is equally beneficial when dealing with reflections on glass windows, car windshields, and even shiny objects like jewellery.

Increased contrast: By reducing scattered light and enhancing colour saturation, polarizers automatically increase the overall contrast in your images. This creates a more defined and visually appealing scene, drawing the viewer’s eye to the essential elements and enhancing the overall impact of the photograph.

Types of Polarizer Lens Filters

While the basic principle remains the same, there are two main types of polarizer lens filters:

Circular Polarizer (CPL): This is the most common type used by photographers. It allows you to rotate the filter while looking through the viewfinder, adjusting the polarisation effect to achieve the desired result. This is crucial for fine-tuning the filter’s impact on various reflections and scattered light.

Linear Polarizer: This type doesn’t allow for rotation, offering a fixed level of polarisation. It’s primarily used for specialised scientific or technical applications and not commonly used in photography.

The Downside of Polarizer Filters

Light loss: Polarizers absorb some light, typically around 1-2 stops. This might require adjusting your camera settings like aperture or shutter speed to compensate, especially in low-light situations.

Autofocus limitations: Some cameras might experience slight autofocus issues with a polarizer attached, particularly older models or cameras with specific sensor types.

Colour shift: In some situations, particularly at wide angles or with certain lenses, slight colour casts might occur. Experimentation and adjustments might be necessary to achieve the desired results.

How to Use a Polarizer

While looking through the viewfinder, rotate the filter to observe how the effect changes. Adjust it until you achieve the desired level of polarisation for your scene.

Pay attention to the direction of your camera and the intended effect. Polarizers work best when the light source (usually the sun) is at a 90-degree angle to your camera position.

Like any tool, mastering a polarizer filter requires practice. Play around with the filter in different lighting conditions and subjects to understand its impact and hone your skills.

When to Use a Polarizer Filter (And Not)

Use for:

• Boosting blue skies and adding vibrancy to foliage
• Reducing reflections on water, glass, and other shiny surfaces
• Increasing contrast, adding visual separation and depth
• Controlling glare in portraits and still-life photography

DON’T Use for:

• Direct glare from the sun: Trying to remove the sun itself will have little effect.
• Metallic surfaces: Polarizers don’t significantly filter reflections off metals.
• Evenly lit scenes without strong reflections: The polarisation effect will be minimal.
• Overcast days: Polarising an already diffused sky won’t have much impact.

Are Polarizers Good for Rainbows?

Unfortunately, polarizers generally work against capturing vivid rainbows. Rainbows themselves are created from refracted and polarised light. Using a polarizer further filters this polarised light, weakening or even removing the rainbow entirely.

Best Polarizer Filters for Photography

Here’s a mix of affordable and premium options to suit different budgets:

Budget-Friendly

• Tiffen Circular Polarizer: A trusted, well-balanced option for beginners.
• Hoya Circular Polarizer: Known for good value and optical quality.
• AmazonBasics Circular Polarizer: A very budget-friendly entry point for experimenting with filters.

Premium

• B+W Kaesemann Circular Polarizer: Professional-grade with outstanding clarity and minimal colour shifting.
• Breakthrough Photography X4 CPL: Premium optics and durable construction for discerning photographers.
• NiSi Circular Polarizer: Offers excellent image quality and innovative filter housing designs.

Don't Forget...

Purchase the correct filter size to match your lenses thread diameter (you’ll find this marked on the lens). Circular polarizers are ideal for photography as they allow for on-the-fly adjustments while shooting.

A polarizer lens filter is a valuable addition to any photographer’s toolkit. It offers a simple yet powerful way to enhance your images with richer colours, reduced glare, and increased contrast.

Understanding its properties, knowing when to use it, and practising its application will unlock a new level of creativity and visual impact in your photography. So go forth, explore, and capture the world around you with the magic of a polarizer filter!

(iPhotography may make small commissions from links in this article.) 

For more, read our guide to long exposure photography.

Frequently Asked Questions

What does a polarising filter do?

It blocks certain reflected light, which reduces glare and reflections on water, glass and foliage, darkens blue skies and makes colours richer.

What is the difference between a CPL and a linear polariser?

A circular polariser (CPL) works correctly with modern autofocus and metering, while a linear polariser can confuse them. For most cameras, choose a CPL.

When should I use a polarising filter?

On bright days for deeper skies and less haze, when shooting water or wet foliage to cut reflections, and for landscapes where you want richer colour. Rotate it until you see the effect.

Does a polarising filter reduce light?

Yes, typically by one to two stops, so you may need a slower shutter speed, wider aperture or higher ISO. Remove it in low light when you do not need the effect.

Can I leave a polariser on all the time?

It is best not to. It cuts light and works unevenly with wide-angle lenses and at the wrong angle to the sun. Use it when its effect helps the shot.