What filters do and when to use them

A filter is a piece of glass or plastic that screws onto the front of your lens and changes how light reaches your camera's sensor. Filters let you darken skies, reduce glare from water, warm up cool light, or protect your lens from dust and damage. Unlike editing software, filters work in real time — you see the effect through your viewfinder before you take the shot.

The main reason to use a filter instead of editing later is control. A polarizing filter can bring back color in a washed-out sky that editing cannot recover. A neutral density filter lets you use a slow shutter speed in bright sunlight, something no post-processing can undo. Some filters solve problems that exist only at the moment you take the picture.

Most photographers start with two or three filters and add more as they discover what they need. A beginner does not need every type — you can shoot for years with just a polarizer and a neutral density filter.

Key Takeaways

  • Filters screw onto your lens and change light before it reaches the sensor, letting you darken skies, reduce reflections, or slow your shutter speed in bright light.
  • A polarizing filter removes glare from water and glass and makes blue skies deeper without affecting other colors.
  • Neutral density filters darken the entire image equally, letting you use slower shutter speeds or wider apertures in daylight.
  • Graduated neutral density filters darken only the top or bottom half of the frame, useful for balancing bright skies against darker land.
  • Filters come in different sizes based on your lens diameter, which is printed on the lens barrel as a number preceded by a ø symbol.

Polarizing filters: removing glare and deepening color

A polarizing filter removes reflections from water, glass, and other shiny surfaces. It also makes blue skies noticeably deeper and richer without changing other colors. This is one of the most useful filters for landscape and outdoor photography because the effect is when ready and cannot be fully replicated in editing.

To use a polarizing filter, screw it onto your lens, look through the viewfinder, and slowly rotate the filter ring. You will see the effect change as you turn it — the sky gets darker, reflections fade, and colors pop. Stop rotating when the effect looks right to you. The strongest effect usually happens when the sun is to your side, not behind you or directly in front of you.

One important note: polarizing filters reduce the amount of light reaching your sensor, so your camera will need a slightly slower shutter speed or wider aperture to keep the same exposure. Most cameras adjust for this automatically, but it is worth checking your shutter speed after you attach the filter.

Neutral density filters: slowing your shutter in bright light

A neutral density filter, or ND filter, darkens the entire image evenly without changing color. It lets you use a slower shutter speed or wider aperture even in bright sunlight. This is useful when you want to blur moving water, show motion in clouds, or shoot with a shallow depth of field on a sunny day.

ND filters come in different strengths, usually labeled by how many stops of light they block. A 3-stop ND filter blocks three stops of light, meaning you can use a shutter speed three stops slower than normal. A 6-stop or 10-stop filter blocks more light and lets you use even slower speeds — useful for long exposures that turn moving water into silk or clouds into streaks.

To use an ND filter, screw it on, set your camera to the shutter speed or aperture you want, and let your camera meter the scene. Because the filter is neutral, it will not shift the color of your image. Some photographers use a very strong ND filter (10 stops or more) to create intentional blur and motion in daylight, an effect that would be impossible without the filter.

Graduated neutral density filters: balancing bright skies

A graduated neutral density filter, or GND filter, is dark on one half and clear on the other, with a gradual transition between them. It darkens only part of your frame — usually the sky — while leaving the land or water below unaffected. This solves the common problem of a bright sky that forces you to underexpose the land to keep the sky from blowing out.

GND filters come in different strengths (usually 1, 2, or 3 stops) and different transition styles. A hard-edge GND has a sharp line between dark and clear, useful when your horizon is straight. A soft-edge GND has a gradual fade, better when your horizon is uneven or when you want the effect to be less obvious. A reverse GND is darkest at the horizon and fades as it moves up, useful for sunsets where the brightest light is right at the horizon line.

To use a GND filter, position it so the dark half covers the sky and the clear half covers the land. Look through your viewfinder and adjust the filter up or down until the sky and land are balanced — the sky should be bright enough to show detail, and the land should not be too dark. GND filters require a filter holder that lets you slide the filter up and down, unlike polarizers and ND filters which screw directly onto the lens.

Filter sizes and how to match them to your lenses

Filters are sized by the diameter of your lens, printed on the lens barrel as a number preceded by ø (the diameter symbol). Common sizes are 52mm, 58mm, 62mm, 67mm, 72mm, and 77mm. You must buy a filter that matches your lens size, or it will not fit.

If you own multiple lenses with different diameters, you have two options. You can buy separate filters for each lens — the most expensive route but the simplest. Or 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 77mm filter fit onto a 72mm lens, for example. This works well for screw-on filters like polarizers and ND filters, but graduated filters in holders are harder to adapt.

Before you buy, check the diameter of each lens you plan to use with filters. Write down the sizes so you do not forget them at the store.

How to attach, remove, and care for filters

Screw-on filters attach by twisting them onto the threaded ring at the front of your lens. Align the filter with the lens opening and turn it clockwise until it is snug — do not force it. To remove it, turn counterclockwise. If a filter gets stuck, try wrapping a rubber band around the edge for grip, or ask another photographer for help rather than risk stripping the threads.

Keep your filters clean. Dust and fingerprints reduce sharpness and can cause unwanted reflections. Use a soft brush or blower to remove dust, then wipe 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 glass.

Store filters in a protective case or pouch to prevent scratches and damage. Many photographers keep a clear filter (called a UV filter or protection filter) on their lenses at all times to shield the lens glass from dust and accidental bumps. This is optional but inexpensive insurance.

Stacking filters and when not to

You can screw two filters onto the same lens at the same time — for example, a polarizer and an ND filter together. This is called stacking. Stacking works well when you want the effects of both filters, such as reducing glare and slowing your shutter speed at the same time.

However, stacking can cause problems. Each filter adds a small amount of glass in front of your lens, and too much glass can reduce sharpness, especially at the edges of the frame. Stacking also makes your lens heavier and more front-heavy, which can stress the lens mount. If you stack filters, use only two at a time, and avoid stacking on very wide-angle lenses (wider than 24mm) where edge softness becomes noticeable.

Most photographers avoid stacking graduated filters because the effect becomes hard to control. If you need both a GND and a polarizer, use the GND in a holder and the polarizer screwed on, or use them on separate shots.

Frequently Asked Questions

Do I need filters if I edit my photos in Lightroom or Photoshop?

Some effects cannot be replicated in editing. A polarizer removes reflections and deepens skies in ways that editing cannot fully recover. A neutral density filter lets you use a slow shutter speed in daylight, which editing cannot undo — the motion blur is created at the moment you take the shot. Graduated filters balance a bright sky against darker land in a way that looks natural, while editing often looks artificial. Filters solve problems at capture time; editing solves problems after.

What is the difference between a circular and a square filter?

Circular filters screw onto your lens and stay in one position. Square filters slide into a holder that attaches to your lens, letting you move the filter up and down. Circular filters are simpler and cheaper for polarizers and ND filters. Square filters are better for graduated filters because you can position the dark area exactly where you need it. Most photographers use circular filters until they need the flexibility of square filters.

Can I use the same filter on all my lenses?

Only if all your lenses have the same diameter. If they do not, you can buy filters for your largest lens and use step-up rings on smaller lenses. Step-up rings are cheap and work well for screw-on filters. Graduated filters in holders are harder to adapt because the holder itself takes up space.

Will a filter make my photos look worse?

A quality filter from a reputable brand will not noticeably reduce sharpness or image quality. Cheap filters with poor glass can cause softness, color shifts, or reflections. Spend a little more on a filter from a known brand like B+W, Hoya, or Lee. A good filter costs between fifteen and fifty dollars depending on size and type, and will last for years.

What filter should I buy first?

Start with a polarizing filter. It solves real problems — glare on water, washed-out skies, reflections on glass — and the effect is visible when ready. Once you understand how filters work and what you need, add a neutral density filter for long exposures or a graduated filter for landscape work. You do not need every type of filter to take good photographs.