Camera Lens Filters: The Basics

Here’s a quick rundown on using some of the most common types of screw-in filters and considerations when using them.

Polarizing Filter Comparison Test Header
Text & Photos By David Coleman
Last Revised & Updated:
Filed Under: Lens Filters

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Here’s a quick rundown on using some of the most common types of photography filters and considerations when using them. I’m focusing here on screw-in filters for DSLRs and mirrorless cameras.

What a Polarizer Filter Does

A polarizer (or polarizing filter) cuts glare. In doing that, it makes many scenes more vibrant, with richer colors, darker skies, clearer water, and fewer reflections.

There are different kinds of polarizer filters. The most common in photography are linear and circular polarizers. Linear polarizers are less expensive, but they don’t work on DSLRs or mirrorless cameras that use through-the-lens metering and autofocusing.

Circular polarizers don’t have that limitation, but they are also more expensive. They have two pieces of treated glass that rotate relative to each other. As you rotate the front piece, the strength of the effect changes because the maximum effect is when perpendicular to the light source.

Polarizer Filter Tests - With Filter

There are some considerations when using a polarizer filter. One is that they slightly reduce the amount of light passing through the lens, typically by around 1.5 to 3 stops. Another is that some thicker polarizers can introduce vignetting on some lenses. They don’t work as well on very wide-angle lenses. They don’t work well with most lens hoods. And they don’t work well with lenses where the front element rotates when focusing.

I’ve put together some practical examples of the effect of polarizer filters as well as a side-by-side shootout of some common circular polarizers.

What a Neutral Density (ND) Filter Does

A neutral density filter reduces the amount of light passing through the lens and hitting the sensor (or film). A standard neutral density filter has consistent filtering across the whole filter (i.e., it’s the same amount of dark across all of it). Ideally, they should be a completely neutral gray that doesn’t impart any color cast to the image.

A graduated neutral density filter is darker on one side than another. A common use for those is in landscape photography to even out the light levels from a bright sky and a darker foreground.

Standard neutral density filters are typically used to slow down the shutter speed. Some practical examples are exaggerated motion blur like a silky smooth waterfall, to “remove” people from an architectural landmark, to match a specific shutter speed to framerate (in video), to eliminate the risk of propellers in the shot (in drones or helicopter shooting), or to be able to use a wide aperture in bright conditions or with flash when high-speed sync isn’t an option.

Neutral density filters come in different strengths, ranging from subtle to almost opaque. Confusingly, there are a few different rating systems. For example, an ND0.9, ND8, and ND103 rating all refer to the same amount of light reduction (in this case, it’s a 3-stop reduction).

ND Filter with Long Shutter Speed

There are also variable neutral density filters that work by rotating two pieces of glass by each other to adjust the strength of the effect.

Again, there are considerations in using a neutral density filter. They work best when the camera is mounted securely on a tripod or other mount point. Darker ND filters can interfere with a camera’s autofocus. And there is often a risk of color casts coming into play, whether from an imperfectly neutral cast in the filter itself or the effects of how sensors (or film) react to long exposures.

What a UV/Haze/Protection Filter Does

A UV or haze filter cuts down some parts of the light spectrum to increase clarity through hazy or glare conditions (but to a much lesser extent than a polarizer filter). But because their effect is so subtle, they have little negative impact on image quality, and they’re relatively inexpensive, photographers often use them as a layer of protection for the lens. Dropping a lens or scratching against other gear in a camera bag is much less expensive when you only have to replace a relatively inexpensive filter rather than a whole lens.

Some photographers argue that any extra glass between the sensor and the scene will have a negative effect, however minimal, and therefore prefer not to add a protection filter. Others argue that there’s little practical optical difference and that the benefits of having that extra layer of protection outweigh those minimal effects. Basically, it’s one of those things that comes down to personal preference.

Things to Watch For with Screw-in Filters

When using screw-in filters, there are some considerations to factor in. Here are a few of them.

Stacking Filters

Many filters (but not all) have a thread on their front as well. That lets you attach another filter on top of it, known as stacking.

What you can get away with here depends on the quality of the filters you’re using as well as the specific lens you’re using. Better quality filters generally have fewer negative optical effects, so they might get away with more pieces of glass before image quality starts to suffer much.

On wide-angle lenses, in particular, there’s a risk that the filter’s frame will start to be visible in the shot, leading to vignetting around the corners and edges. Stacking multiple filters on top of each other increases that risk,

Step-Up/Step-Down Filter Rings

Ideally, you’d have a filter that exactly matches the lens diameter. But that’s not always practical.

Step-up and step-down filter rings don’t have any glass—so they’re not filters. They’re adapters that bridge the gap between the lens diameter and the filter diameter when you don’t have the perfect fit available. For example, they’d let you use a 77mm filter on a lens with a 68mm diameter.

They’re inexpensive and small, and relatively convenient to keep in your camera bag. You can buy them individually or as kits with multiple rings.

The biggest negatives relate to using step-down filters; that is, putting a smaller filter on a larger lens. That usually leads to vignetting (you can change the crop from full-frame to APS-C on some cameras, which can be a workaround).

Wide-Angle Filters

As I mentioned above in the stacking filters part, wide-angle lenses are particularly prone to vignetting when adding filters. So, with wide-angle lenses, it’s often a good idea to be especially mindful of stacking.

In some cases, you can also find slim filters that are designed for wide-angle lenses. They’re especially useful for avoiding vignetting.

And some very wide-angle and fisheye lenses have bulbous front glass and won’t accept a screw-on filter.

Lens Hoods

Whether you can use a screw-on filter at the same time as a lens hood depends on the specific lens. Some work well; some don’t. And some dedicated lens hoods even are designed to function as filter holders themselves.

Lens hoods tend to be inconvenient when using circular polarizer filters or variable neutral density filters.

Don’t Over-Tighten Them

Filters should go on finger tight. Doing them too tight risks damaging the fine threads on the lens or filter or both, which are usually made of relatively soft brass, aluminum, or plastic.

If you have a filter that stubbornly won’t come off, try a rubber band, (clean) kitchen gloves, or a filter wrench.

Lens Filter Size Charts

I’ve compiled some lens filter size charts, starting with some of the most commonly used and current lenses. You can find the corresponding chart here:

And you can also use step-up and step-down filters if you don’t have the exact size filter on hand.

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David Coleman

I'm a professional photographer based in Washington, DC. Seven continents, up mountains, underwater, and many places in between. I've been shooting for 30+ years, and my photos and time-lapse videos have appeared in a bunch of different publications, from major newspapers to magazines and books, billboards, TV shows, professional sports stadiums, museums, and even massive architectural scrims covering world-famous buildings while they're being renovated. You can see some of my travel photography here and here.