The best neutral density filters in 2020: ND filters for longer exposures

Investing in one of the best neutral density filters is a fantastic way to give your landscape photography an instant upgrade. Long exposures can often be the secret ingredient to take an image from zero to hero – but if your scene is too bright then you'll need one of these filters to achieve this effect.

If you're in need of the best ND filter, then you're in luck. We've rounded up the best neutral density filters to help you find the perfect one for you. Landscape and cityscape photography can benefit hugely from long exposures, which will smooth out water, get rid of any wandering pedestrians and capture beautiful light trails in low light conditions. However, photographers will often find that there's too much light in their scene with a bare lens. 

Using a narrow aperture, such as f/22, and setting a low ISO can sometimes be enough to help you achieve a slow enough shutter speed.However, sometimes the best option is to artificially cut down the amount of light coming through the lens with a neutral density filter. 

However, it's not quite so simple as randomly picking a filter and hoping for the best. For the best chance of success, you'll need to select the right density option. Too strong and you'll end up with an exposure longer than necessary (which can introduce unwanted noise into your photo). Too weak and you won't get the long exposure effect that you're seeking. 

The best ND filters come in different density options that are defined by several numbering scales. The different numbers might seem intimidating or confusing at first, but you'll soon get used to it! For example, ND 1.8 and ND64 both describe a filter that cuts light transmission by six f-stops. This means that you'd be able to use a shutter speed that's six stops slower than without the neutral density filter.

Six stops of reduced light should be plenty when working in low light conditions such as dawn or dusk. However, if you're working in direct sunlight and you're looking for super long exposures to blur water or sky, then you might want to use an ND 3.0/ ND1000 filter instead. This will give you 10 stops of reduced light to play with, which can make an incredible difference to your scene.

To help you find the best neutral density filter for you, we've tested both round and square ND filters. We've explored whether any of the below options reduce image sharpness or produce an unwanted color cast. 

Cokin’s Nuances Extreme ND filters come in 6-stop and 10-stop densities, which is an ideal choice for long exposure photography. They can also be had in three sizes: P-size (84x100mm), Z-Pro (100x100mm), and X-Pro (130x130mm). We went for the Z-Pro option as this is the best balance of portability and versatile lens coverage. Their tempered mineral glass with rounded corners is said to be drop resistant, while a nano metallic alloy coating gives a more uniform density and better colour neutrality.

And our testing proved this to be more than just marketing hyperbole. Both our 6-stop and 10-stop filter samples were joint best with the Lee IRND filters for colour accuracy. Sharpness at all points in the image frame was also flawless, and both filters exactly matched their f-stop light reduction ratings.

Cokin’s EVO filter holder is an ideal match for Nuances Extreme filters. It’s beautifully made and features a very effective foam gasket to guard against light leaks during a long exposure, but it is not the cheapest option.

LEE Filters has long been the go-to brand for uncompromising filter quality, and its latest ProGlass IRND range is said to be the new benchmark in ND performance. Six density options are available, with a typical 2-stop to 10-stop range, but there’s also a super-dark 15-stop variant for extremely long exposures.

The IRND name signifies that the filter coating blocks infrared and ultraviolet light for better image contrast, and LEE is claiming top notch exposure consistency and colour accuracy. We tested the 6-stop and 15-stop filters in the IRND line-up and both did indeed have absolutely no impact on colour accuracy in our testing. Image sharpness was also flawless, with both filters maintaining perfect centre, mid and corner-frame crispness.

With such long exposures possible, LEE has come up with a companion app to help you calculate optimal exposure times. You’ll also need a suitable 100mm filter holder to use IRND filters, with the obvious choice being the latest LEE100 holder. Finally, a lens adaptor ring is required to attach the holder to your chosen lens.

Hoya’s Pro ND range of circular filters comes in ND4 to ND1000 variants for a 2-stop to 10-stop shutter speed reduction. Most common filter thread diameters are catered for by the 49mm-82mm size range, though the frame is slightly deeper than the B+W and Marumi circular filters, which could introduce minor vignetting when shooting with a very wide lens.

As you’d expect, Hoya is keen to promote the ProND’s colour neutrality and exposure accuracy, with features like a Metallic ACCU-ND coating on both sides of the glass. And whatever this really is, it does work. We tested the ND64 (6-stop) and ND1000 (10-stop) ProND versions and found them to be the only round filters on test to have no negative impact on image sharpness at any point in the frame. Colour accuracy was a shade off the standard set by the best square filters, but a 0.5% deviation from the ND64 and a 1.3% difference from the ND1000 won’t be visible in real-world shooting.

A 77mm ProND 1000 compares well with similar rival filters on price, making it reasonable value for its decent image quality.

The H&Y name may be new to the filter scene, but the company has actually been manufacturing filters for other brands for many years, and having recently made waves with its innovative magnetic filter frames, H&Y is now putting its name to the filters themselves.

The K-series (100x100mm) square ND filters come in useful 6-stop and 10-stop densities. Both use multi-coated glass that avoids color casts while also resisting moisture, fingerprints and scratches.

Our testing revealed the 6-stop filter to be perfectly color-accurate, while the 10-stop was just 1.2% off the mark, most likely due to it being fractionally less dense than its 10-stop rating. Both filters produced a flawless image sharpness result.

The filters are even more appealing as they come with H&Y’s nifty magnetic filter frame which would cost £23/ $35 separately. It makes the filters much easier to fit and means you never touch the glass. The only drawback is the foam gasket doesn’t quite seal the filter perfectly against light leakage.

ND filters produce the most dramatic results when using very long exposures, so Marumi’s DHG Super range only contains high-density 9-stop and 10-stop options. Both are round screw-in-type filters, available in all common diameters from 49mm through to 82mm. We’re quoting prices for the 10-stop (ND1000) filter, but the ND500 pricing is similar.

The filter’s shallow frame depth helps avoid vignetting when shooting with an ultrawide lens, and its satin finish reduces reflections. The filter glass also has a scratch-resistant coating.

Sadly, neither our Super ND500 or ND1000 sample filters managed a flawless performance in our testing. The ND500 produced a 2.5% colour shift from optimal, and the ND1000’s colour deviation was worse at 4%. Image sharpness was also negatively affected. Both filters maintained perfect centre-frame sharpness, but reduced mid-frame sharpness by a noticeable 20% in the case of the ND500, while the ND1000 produced a 24% drop. Sharpness in the corners of frame wasn’t quite so badly affected, but both filters still gave the worst results of the group.

Screw-in filters may not quite have the kudos of a square or rectangular filter system, but B+W’s round XS-Pro filters certainly aren’t short on features. Their MRC Nano (Multi-Resistant Coating) helps shed dirt and water, and we found it does indeed do a good job of beading away rain drops. Further coatings reduce reflections, while SCHOTT glass (drinks, anyone?) increases optical clarity and colour fidelity. Thread diameters range from just 30.5mm all the way up to 95mm, and you can have 2, 3, 6 or 10-stop densities. Whichever option you go for, you get an exceptionally shallow frame depth that makes these filters great for ultra-wide photography.

However, our samples weren’t quite so great in our image quality tests. The 3-stop version produced excellent results in our colour accuracy and sharpness tests, but the 6-stop and 10-stop filters introduced some issues. Both our samples were ⅓-stop too dark, requiring exposure compensation to maintain accurate colour. Mid-frame and corner sharpness also dropped 5% with the 6-stop filter fitted, and by 20% with the 10-stop filter. Not great considering the hefty price commanded by the larger-diameter filters.

Six things to look out for when buying an ND filter…

Round ND filters: A circular ND filter is fantastic – as long as you only want to use it with one lens thread diameter. However, it's convenient to use and rarely lets in light leaks. If you want do want to adapt it for other lenses, you can use stepping rings to adapt a larger filter to fit a smaller lens (but you can't do this the other way round).

Square ND filters: While they require a holder and an adaptor ring, the great thing about square ND filters is that they can be used with multiple lenses. To avoid disappointment, make sure the filter is attached properly to prevent light leaks. 

Go slow: If you want to capture truly minimalist land-, sea- and city-scapes, you'll need a very dense ND1000 (10-stop) filter to help slow down your shutter speed to achieve your desired result.

Keep it sharp: Neutral density filters should do what they say on the tin – remain neutral. While color casts can be corrected in image editing programs, any fuzziness from poor glass quality will be much more difficult to fix (likely impossible). 

Extra effects: A square ND system opens up possibilities for stacking filters like a polarizer or graduated ND filters for images with even more appeal.

Variable ND filters: These handy little filters have adjustable density, and are particularly useful for controlling exposure in video, see separate guide to best variable ND filters.

ND filter reference table

Neutral Density filters are made in wide number different strengths, and different scales are used to measure this. Some manufacturers use an NDxx number, others can quote a number for the  optical density, and some use a figure to describe  the light reduction in ‘stops’. 

The table here compares the systems and shows how much slower a shutter speed each filter type will let you achieve with your camera.

Lab data

We lab tested each filter by attaching it to a Sigma 50mm f/1.4 EX DG HSM lens mounted to a Canon 5D Mark III body. Images of specialist charts designed to test lens sharpness and color accuracy were then captured using a shutter speed reduction equivalent to the f/stop density rating of the filter being tested.

The resulting images were then processed using Imatest Master analysis software to determine the impact each filter has on sharpness and color accuracy. The percentage differences in sharpness and color deviation from a non-filtered control image are displayed in the graphs below.

This graph shows the percentage impact each filter has on image sharpness. The ideal score is 100%. Almost all the filters managed this when testing centre-frame sharpness, but the higher-density B+W filters, and both Marumi filters on test, had a significant impact on sharpness in the mid-frame and corner-frame image regions.

A score of zero on this graph indicates ideal color unaffected by the filter, with longer bars showing a more obvious color cast. It's worth noting that inaccurate filter density ratings will impact on the score in this test. So for filters that produced an over or underexposed image when we reduced the camera's shutter speed by the same number of f/stops as the filter's density rating, we also used a slightly slower or faster shutter speed to counteract the issue, indicated by asterisks around the filter name on the graph.

In the case of the Marumi filters, both were accurate to their density ratings, so the poor results here are due to color casts.

Finally, the LEE 15-stop filter initially produced a poor result, but came good when using a further 1/3-stop longer exposure. However, as we needed to use a combination of shutter speed reduction, a larger lens aperture, and a higher ISO sensitivity to compensate for the huge 15-stop light reduction, we're giving the filter the benefit of the doubt and assuming it to be accurate to its 15-stop rating.

Read more:

• 10 things you need to know about camera filters – and which ones to buy
• Best variable ND filters
• 50 best camera accessories in 2020
• Best protection filters for lenses
• How to use ND filters for long exposures during the day
• How to shoot and process long-exposure seascapes
• The best polarizing filters