What photography filters do and when to use them

A photography filter is a piece of glass or plastic you screw onto the front of your camera lens to change how light reaches the sensor. Filters work by blocking, absorbing, or shifting certain wavelengths of light before the image is recorded. Unlike editing software that changes a photo after you take it, filters alter the light in real time, which means what you see through the viewfinder is close to what you'll get in the final image.

Filters fall into two broad categories: those that reduce light (neutral density and polarizing filters) and those that shift color (warming and cooling filters). You use them when you need to control exposure in bright conditions, cut glare and reflections, or match the color temperature of your scene to what your camera sees. A polarizing filter on a sunny beach cuts the glare off water and makes the sky deeper blue. A neutral density filter lets you use a slower shutter speed in daylight without overexposing. A warming filter adds orange tones to a scene shot in cool, blue light.

Key Takeaways

  • Filters screw onto your lens and change light before it hits the sensor, so the effect shows in your viewfinder and requires no editing afterward.
  • Polarizing filters reduce glare and reflections and deepen blue skies, making them useful for landscape and water photography.
  • Neutral density filters darken the entire image equally, letting you use slower shutter speeds or wider apertures in bright light.
  • Warming and cooling filters shift the overall color tone of your image, useful when your camera's white balance is not matching the light in your scene.
  • Filter size is measured in millimeters and must match your lens diameter, printed on the lens barrel or in your lens manual.

Polarizing filters: cutting glare and deepening color

A polarizing filter blocks light waves that bounce off reflective surfaces like water, glass, and wet pavement. When you rotate the filter while looking through the viewfinder, you'll see the glare and reflections fade. The effect is strongest when the sun is at a 90-degree angle to your subject — shooting across a lake or toward a window works better than shooting directly into the sun.

Polarizing filters also deepen blue skies and make clouds stand out more, because they reduce the scattered light that makes the sky look pale. The trade-off is that they cut about one to two stops of light, so your camera will need a slower shutter speed or wider aperture to maintain the same exposure. On an overcast day or indoors, a polarizing filter may darken your image too much to be useful.

To use a polarizing filter, screw it onto your lens, look through the viewfinder, and slowly rotate the filter ring until the glare or reflection disappears or the sky reaches the color you want. The effect changes as you move or as the sun moves, so check your viewfinder again before you shoot. Most polarizing filters are circular (the type that rotates) rather than linear, because circular filters work better with modern autofocus systems.

Neutral density filters: shooting slow in bright light

A neutral density (ND) filter is a gray piece of glass that reduces the amount of light entering your lens without changing color. ND filters come in different strengths, measured in stops — a 3-stop ND filter cuts light by three stops, a 6-stop cuts it by six stops, and so on. The stronger the filter, the darker it is.

You use an ND filter when you want to use a slow shutter speed or wide aperture in bright conditions. In full sunlight without a filter, you might be forced to shoot at 1/2000 of a second at f/16 to avoid overexposure. With a 6-stop ND filter, you can shoot at 1/30 of a second at f/4, which lets you blur moving water or clouds, or blur the background while keeping the subject sharp. ND filters are essential for long-exposure photography — waterfalls, flowing rivers, and silky clouds all require shutter speeds of several seconds, which is impossible in daylight without a strong ND filter.

To use an ND filter, screw it onto your lens, compose your shot, and set your exposure as if the filter were not there — your camera's meter will read the darker image and adjust automatically. If you're using a very strong filter (10 stops or more), you may need to focus before attaching the filter, because the image will be too dark to focus through. Check your final image on the back of the camera to confirm the exposure is correct.

Warming and cooling filters: shifting color temperature

Warming filters add orange or amber tones to your image, while cooling filters add blue tones. These filters are useful when the light in your scene does not match what your camera's white balance is set to. If you're shooting indoors under tungsten bulbs and your camera is set to daylight white balance, the image will look too orange — a cooling filter or a white balance adjustment will fix it. If you're shooting at sunset and want to enhance the warm tones, a warming filter will push the color further in that direction.

Warming and cooling filters come in different strengths, often labeled by color temperature in Kelvin or by a number system (81A, 81B, 82A, 82B, and so on). An 81A filter adds a mild warm tone, while an 81EF adds a stronger one. An 82A filter adds a mild cool tone. You choose based on how much color shift you want and what light you're shooting in.

To use a warming or cooling filter, screw it onto your lens and shoot. The color shift will show in your viewfinder. If you want to fine-tune the effect, you can also adjust your camera's white balance setting — for example, setting it to a warmer white balance (like tungsten) will add warmth on top of what the filter is already doing. Check your images on the back of the camera to see if the color matches what you want.

Finding the right filter size for your lens

Filters are sold by diameter, measured in millimeters. Common sizes are 52mm, 55mm, 58mm, 62mm, 67mm, 72mm, 77mm, and 82mm. Your lens diameter is printed on the lens barrel, usually near the front, and looks like a circle with a line through it followed by a number — for example, ⌀55mm means your lens takes 55mm filters.

If you don't see the size on your lens, check your lens manual or search the lens model number on the manufacturer's website. If you own multiple lenses with different diameters, you can buy filters for your largest lens and use step-up rings to attach them to smaller lenses. A step-up ring is a cheap adapter that lets a smaller lens use a larger filter. You cannot use a smaller filter on a larger lens without vignetting (dark corners in the image).

When you buy a filter, make sure you're getting the right size. A 52mm filter will not screw onto a 58mm lens, and forcing it can damage both the filter and the lens threads. If you're unsure, bring your lens to a camera shop and ask them to check the size for you.

How to attach and remove filters safely

To attach a filter, hold the lens in one hand and screw the filter onto the front of the lens with your other hand. Turn it clockwise until it is snug — you should not need to force it. If the filter is hard to turn, stop and check that the threads are aligned straight; if they are crossed, you can strip the threads and ruin the filter or the lens.

To remove a filter, turn it counterclockwise. If a filter is stuck, do not use pliers or a wrench — you can crack the glass. Instead, run warm water over the stuck filter for a few seconds to expand the metal slightly, then try again. If it's still stuck, take it to a camera shop; they have tools to remove stuck filters without damage.

Always keep a lens cap on your filter when you're not shooting. Filters protect your lens from dust and scratches, so it's better to have a scratched filter than a scratched lens. If your filter does get scratched, you can replace it cheaply. A scratched lens is much more expensive to repair.

Stacking multiple filters and managing light loss

You can screw two or more filters onto the same lens at the same time — for example, a polarizing filter and a neutral density filter together. When you stack filters, the light loss adds up. A polarizing filter cuts about 1 stop, and a 3-stop ND filter cuts 3 stops, so together they cut about 4 stops of light. Your camera's meter will account for this automatically, but you should be aware that stacking filters can make your viewfinder darker and harder to focus through.

If you stack more than two filters, you may see vignetting (dark corners) in your image, especially if you're using a wide-angle lens. To avoid this, buy filters with thin frames designed for stacking. When you stack filters, screw the thinnest one on first, then the thicker ones on top.

Frequently Asked Questions

Do I need a filter if I can edit the photo afterward?

Filters and editing do different things. A polarizing filter cuts glare and reflections that editing cannot recover — once the glare is in the image, no software can remove it cleanly. An ND filter lets you use a slow shutter speed to blur motion, which editing cannot replicate. Warming and cooling filters shift color, which you can also do in editing, so those are more optional. If you shoot in RAW format, you have more control over color in editing, so warming and cooling filters matter less.

Can I use filters on my phone camera?

Phone cameras have fixed lenses that do not accept screw-on filters. You can buy clip-on filters that attach to the phone body, but they are not as effective as lens filters because they do not sit directly in front of the lens. For serious filter work, you need a camera with interchangeable lenses or a fixed lens with a filter thread.

What's the difference between a circular and linear polarizing filter?

A circular polarizing filter rotates to adjust the effect and works with autofocus. A linear polarizing filter does not rotate and can interfere with autofocus and metering on modern cameras. Buy a circular polarizing filter unless you have an older film camera or a specific reason to use linear.

How do I clean a filter?

Use a soft brush or blower to remove dust, then breathe gently on the glass to create condensation and wipe it with a microfiber cloth. For stubborn smudges, use a lens cleaning solution made for camera glass — do not use window cleaner or paper towels, which can scratch the filter. If your filter is dirty on the inside (between the glass and the frame), it cannot be cleaned safely and should be replaced.

Do expensive filters work better than cheap ones?

A good polarizing or ND filter from a reputable brand will perform better than a cheap one — the glass is clearer, the coatings reduce reflections, and the frame is more durable. Cheap filters can introduce color casts or reduce sharpness. For warming and cooling filters, the difference is smaller because they are straightforward pieces of colored glass. Spend more on polarizing and ND filters, and less on warming and cooling filters.