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Six of the best ND filters

B+W XS-PRO Digital ND MRC Nano £52-226/$67-270 www.manfrotto.co.uk

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 increases optical clarity and colour fidelity. Thread diameters range from just 30.5mm all the way up to 95mm, and you can have two-, three-, six- or 10-stop densities. Whichever option you go for, you get an exceptionally shallow frame depth that makes these filters great for use with ultra wide-angle lenses.

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

PROS Huge range of thread diameters and versatile density options available CONS Inaccurate density rating for our sixand 10-stop samples; mediocre sharpness

Cokin Nuances Extreme ND Z-pro £120/$180 www.cokin.com/en

Cokin’s Nuances Extreme ND filters come in six- and 10-stop densities, which is an ideal choice for longexposure 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.

Our testing proved this to be more than just marketing hyperbole. Both our six- 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, although it is expensive at £99/$180.

Nuances Extreme filters are hard to fault in real-world shooting, yet are fairly well priced – making them a winning combination.

PROS Flawless colour accuracy, image sharpness and f-stop accuracy CONS Cokin’s own holder is pricey, but you could use an alternative 100mm holder

H&Y K-series HD MRC Neutral Density £130 www.handyfilters.com

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

The K-series square ND filters (measuring 100x100mm) come in useful six- and 10-stop densities. We’re quoting the price of the 10-stop filter – the six-stopper is £10 less. Both use multi-coated glass that avoids colour casts while also resisting moisture, fingerprints and scratches.

Our testing revealed the six-stop filter to be perfectly colour-accurate, while the 10-stop filter 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 that the foam gasket doesn’t quite seal the filter perfectly against light leakage.

PROS Excellent image quality; nifty magnetic attachment system; keen pricing CONS Slightly behind the Cokin and Lee filters for colour neutrality in our tests

Hoya PROND £35-109/$30-100 www.hoyafilter.com

Hoya’s PROND range of circular filters comes in ND4 to ND1000 variants for a two- 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. This could introduce minor vignetting if you shoot with the filters fitted to a very wide-angle 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 (six-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 will set you back around £99/$87, making it reasonable value for its decent image quality. If you prefer the convenience of a circular filter over square designs, the PROND is your best choice.

PROS Class-leading image quality for a circular filter; fairly well priced CONS Not quite a match for the best square filters in this group

Lee Filters 100x100mm Proglass IRND £179/$237 www.leefilters.com

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 conventional two- to 10-stop range, but there’s also a super-dark 15-stop variant available for shooting extremely long exposures. The IRND name signifies that the filter coating blocks infrared and ultraviolet light for better image contrast, and Lee Filters is claiming top-notch exposure consistency and colour accuracy. We tested the six-stop and 15-stop filters in the IRND line-up, and both did indeed have absolutely no impact upon colour accuracy in our shots. 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 newly introduced £83 Lee100 holder. Finally, a lens adaptor ring is required to attach the holder to your chosen lens. All in all, it’s a substantial investment for undoubted quality.

PROS Sublime image quality; wide range of densities; versatile filter size CONS Quality doesn’t come cheap; new filter holder costs more than outgoing version

Marumi DHG Super ND £38-87/$52-120 www.kenro.co.uk

ND filters produce the most dramatic results when you are shooting very long exposures, so Marumi’s DHG Super range only contains highdensity nine- 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) size range, but the ND500 pricing is similar.

The filter’s shallow frame depth helps avoid vignetting when shooting with an ultra wide-angle 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 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 the frame wasn’t quite so badly affected, but both filters still gave the worst results of the group.

They’re acceptable if you’re on a tight budget, but we’d hoped for a better showing.

PROS Appealing price; good range of thread diameters; useful density options CONS Colour accuracy not quite perfect; image sharpness far from perfect