Taking control of exposure for creative effects is one the pure joys of photography. Neutral density filters are one tool you can use to control exposure in their ability to reduce the amount of light that enters the lens.
We’ve explained what neutral densities filters are and how to use them, but sometimes you want a more compact, all-in-one solution that lets you explore the effects of an ND filter at a range of different densities. This is when you might want to consider buying a variable ND filter.
What is a variable ND filter?
A variable ND filter is a neutral density filter that allows you to just the density of the filter. Typically you twist a ring on the outside of the filter, and the filter shifts between low and high densities (often anywhere from 2 up to 10 stops of light).
When to use a variable ND filter
It’s best to use an ND filter or variable ND filter when you are shooting in strong daylight or other bright conditions and want to shoot with a wide aperture, for instance, to create a shallow depth of field effect. Without an ND filter in this situation you will probably blow out your exposure. An ND filter helps reduce the light coming into your lens, allowing you to shoot at f/2.8, for example, at a reasonable shutter speed.
You might also use an ND filter if you were shooting the sea, for instance, and wanted a long exposure to smooth out the water for that classic milky sea effect. In the daylight you won’t be able to get an exposure long enough to flatten the waves. An ND filter, again, reduces the light hitting your sensor allowing you to shoot at a longer exposure.
When to use a variable ND filter in particular? Variable ND filters are useful because you have control over its opacity. Using our beach example again, if you are photographing a sunset, the light levels will change dramatically over a short period of time. A variable ND filter allows you to keep adjusting the opacity until you no longer need it.
Variable ND filters are also useful for videographers. Say you were filming someone speaking on a street corner and then panned over to a commotion taking place in a dark alley. A variable ND filter lets you seamlessly move your camera from brighter to darker scenes while maintaining the same depth of field in your shot.
Do ND filters affect image quality?
This is a common question, and the answer is no: ND filters will not affect image quality. ND filters only limit the amount of light reaching your camera’s sensor via the lens. You do this in order to get a longer shutter speed. Provided your camera is stable, it will produce sharp, detailed images with an ND filter mounted.
Some of the questions around image quality with ND filters might come down to confusion with colour filters and gels, which can affect your image quality.
How to know when you’ve pushed a variable ND too far
While variable ND filters offer tons of flexibility, sometimes you can push them too far. You’ll know when you’ve done this if you see a funny dark cross in the centre of your scene if you try to darken the image too much – this is a feature of using two sheets of polarising material. And if you use them with a very wide lens there can be variation in the effect across the frame.
What’s more, if you pan in video, the effect may change because polarising filters work best when the sun is to the side of the frame.
Variable ND vs fixed ND filter – what are the differences in image quality?
There are, however, some subtle differences in image quality between variable ND filters and traditional fixed ND filters.
Stills shooters looking for big-resolution, high-quality images (think landscape photographers) will typically opt for a fixed ND filter. Videographers or photojournalists and street and travel photographers might opt for a variable ND filter.
In most instances, a variable ND filter will deliver the image quality you want. But in a few conditions it can struggle.
With reflective surfaces, for instance, a variable ND filter may produce odd tones as you change the strength.
There’s also the issue that with a variable ND filter you are shooting through more layers of glass than you are with a fixed ND filter. This means you can sometimes get softer images.
Then again, with a variable ND filter you might find that you get shots you wouldn’t ordinarily be able to achieve because you don’t have a full set of filter or the time to keep changing them one-by-one.
In short, a fixed ND filter will deliver higher quality images, while a variable ND filter offers far more speed, flexibility and convenience. A variable ND filter will also save you a lot more money in the long run than buying lots of fixed ND filters at different strengths.
What is the best variable ND filter?
Variable ND filters come in a range of sizes and price points. To help you choose, we’ve rounded up seven of the best variable ND filters for your needs, from the high end to the budget options.
1. B+W XS-Pro Digital ND Vario MRC Nano
- Price: £224/$189
- Sizes: 52-82mm
- Multi-Resistant Coating
Schneider Optics’ B+W XS-Pro Digital ND Vario MRC Nano is more than you’ve likely budgeted for a variable ND filter, but it’s the variable ND filter you should buy. What sets the B+W XS-Pro Digital ND Vario MRC Nano apart from others is a Multi-Resistant Coating that perfectly repels water. Rain or sea spray, droplets bead up nicely and roll off the filter. What’s more, this coating also effectively reduces ghosting and reflections.
The B+W XS-Pro Digital ND Vario MRC Nano is a screw-in filter, which is 9mm deep (not including the thread), and provides between 1 and 5 stops of light reduction on your scenes.
In use, you’ll find the front ring rotates and is marked with hard stops to indicate where the different densities are located between the minimum and maximum.
2. Syrp Variable ND Filter
- Price: £139/$139
- Sizes: 52 & 82mm
- Adapter rings
The Syrp Variable ND Filter is also no budget option at £139/$139, but again, it oozes quality and its performance is superb. Interestingly, unlike other filters where you’ll find a range of sizes, Syrp provides two versions: 67mm and 82mm.
The 67mm Small Kit comes with adapter rings that allow you to mount the filter to lenses ranging from 52mm to 58mm. The 82mm Large Kit option provides adapters for lenses from 72mm to 77mm.
So the Syrp offers a lot of flexibility. It also provides near flawless quality in both build and performance. And like the B+W, front coating on the filter makes it water and dust resistant.
3. Marumi DHG Vari ND2-ND400
- Price: £55/$93
- Sizes: 52-82mm
- Weather resistant
Distributed in the UK by Kenro, the Marumi DHG Vari ND2-ND400 offers between 1 and 8 stops of light reduction. While not as expensive as the Syrp and B+W, the Marumi still manages to offer solid build quality.
It’s also very quick and easy to mount to your lens. A textured area on the ridge lets you grip it firmly and rotate with ease.
There are no hard stops like the Syrp and B+W, and nor does it offer the coatings. But as a mid-range option, the Marumi is probably your best bet.
4. Singh-Ray Variable ND Filter
- Price: £/$390
- Sizes: 49-82mm
- Controls up to 8 stops of light
Singh-Ray’s Variable ND filters come in both standard and thin ring options and let you add between two and eight stops of neutral density to your images.
This variable ND will cost you plenty, but its durability and consistent colours all throughout its different density settings will give your images a reliable style and feel.
At this price, if you’re a hobbyist photographer the Singh-Ray might not be for you. But if you’re a professional or advanced enthusiast looking build a consistent body of work, the Singh-Ray Variable ND Filter is just what you need.
5. Hama Vario ND2-400
- Price: From £33
- Sizes: 52-77mm
Hama’s budget offering is a variable ND filter that really punches above its weight. It might not have the same build quality as the Singh-Ray above, but if you’re a hobbyist or just taking your first steps into using ND filters, the Hama Vario ND2-400 is the perfect variable ND for your needs.
Colours and sharpness remain respectably consistent throughout the densities, and beginners will also like how easy this filter is to fit and remove from their lenses.
You won’t find hard stops on the Hama Vario like you do the more expensive ones (there are markings on the ring, however) and there’s no 82mm diameter option. But for price, user friendliness and consistency, this is one of the best variable ND filters out there.
6. Tiffen variable ND filter
- Price: £95
- 2 to 8 stops of light
- Thin profile ring
Tiffen’s variable ND filter provides 2 to 8 stops of light and is one of the most versatile and easy-to-use options you can buy. It’s also designed with a wider outer optic that helps reduce vignetting when you’re shooting at wide angles.
Excellent value for money, the Tiffen variable ND filter is well made and will bring the colour and clarity back to your outdoor videos and images.
7. NiSi Variable ND Filter
- Price: £109
- 1.5-5 stops
- No colour-cast multi-layer coating
NiSi’s high-end variable ND filter offers a shutter speed reduction of 1.5 to 5 stops. You can control the density via a simple screw on the filter ring, which smoothly cycles through light to dark.
NiSi also promises no loss of sharpness thanks to its contrast colour design and a multi-layer coating that reduces unwanted colour casts.
NiSi’s variable ND filter is one of our favourites on this list thanks to the precision it affords.
7. PolarPro Variable ND 2-5Ev Peter McKinnon Edition
- Price: $249
- Fused quartz glass
Etched markings on the aluminium frame of the PolarPro Variable ND 2-5Ev make it easy to make precise adjustments to exposure. The rotating action is smooth and silent, plus vignetting is well controlled. Detail levels are also maintained extremely well.