ND Filter in Photography: What It Is and How to Choose One
Whether you are a beginner or an experienced long-exposure photographer, ND filters are essential tools for controlling light, smoothing motion, and elevating your landscapes. This is a practical, illustrated, and accessible guide to help you understand everything.
An ND (Neutral Density) filter is a photographic accessory that reduces the amount of light reaching the sensitive surface—digital sensor or film—without altering colors. This allows you to extend the exposure time or shoot with a wide aperture even in bright light.
Contents
- How It Works
- ND Filter Equivalence Table
- Types of ND Filters
- Graduated ND Filters (GND)
- Why Use an ND Filter?
- ND Filter Quality
- Filters I Use
- Precautions
- How to Use an ND Filter
- How to Recreate a Long Exposure Effect Without a Tripod
- Long Exposure Example
How It Works
The principle is simple: an ND filter works like a pair of neutral sunglasses for your lens. It reduces the amount of light entering the camera without altering colors or overall tone. This allows you to extend the exposure time or use a wide aperture in bright conditions.
Each ND filter is associated with a density, expressed as NDx (ND4, ND64, ND32000…) or as a number of exposure values (EV/stops). One exposure value corresponds to one f-stop, that is, doubling or halving the amount of light, such as between f/8 and f/11, or between 1/60s and 1/125s.
ND Filter Equivalence Table
| ND Value | Light Reduction | EV Reduction |
|---|---|---|
| ND2 | 1/2 of light | -1 EV |
| ND4 | 1/4 of light | -2 EV |
| ND8 | 1/8 of light | -3 EV |
| ND16 | 1/16 of light | -4 EV |
| ND32 | 1/32 of light | -5 EV |
| ND64 | 1/64 of light | -6 EV |
| ND128 | 1/128 of light | -7 EV |
| ND256 | 1/256 of light | -8 EV |
| ND512 | 1/512 of light | -9 EV |
| ND1000 | 1/1000 of light | -10 EV |
| ND32000 | 1/32000 of light | -15 EV |
Types of ND Filters
There are three main categories of ND filters:
- Screw-in filters: the most common, mounted directly onto the lens thread (diameter 77 mm, 82 mm, etc.).
- Magnetic filters: quick to attach, they use a magnetic adapter to make density changes easier.
- Square or rectangular filters: inserted into a holder. They are often used in landscape photography, sometimes combined with graduated filters.
Graduated ND Filters (GND)
GND filters (Graduated Neutral Density) balance exposure between a bright sky and a darker foreground. They are especially useful at sunrise or sunset.
Types of GND filters include:
- Soft grad: for smooth horizons.
- Hard grad: for sharp transitions (such as mountain ranges).
- Reverse grad: maximum density at the center, ideal for sunsets near the horizon.
Screw-in GND filters have a fixed center gradient, which limits framing flexibility. Square filters in a holder, on the other hand, allow you to adjust both height and angle.
But is it always necessary? With a modern camera and a properly exposed RAW file, sensor dynamic range often allows you to recover highlights or shadows. Using adaptive masks in Lightroom (or other software) can darken only the sky. This is a practical alternative if you are short on space in your camera bag or prefer traveling light, as square filters and holders are bulky and often expensive.
Why Use an ND Filter?
An ND filter is essential for:
- Extending exposure time in daylight without overexposing, especially in landscapes.
- Blurring water or clouds for an ethereal and poetic look.
- Keeping a wide aperture (e.g., f/2.8) for beautiful bokeh even in strong light.
ND Filter Quality: Be Aware of Compromises
Depending on brand and price, ND filters vary in quality. Budget models, often under €30, may show flaws: lack of glass flatness, poor optical quality, or subpar coatings. These imperfections can reduce image sharpness, introduce reflections, or degrade overall resolution—negating the advantages of your high-quality lens.
Another common issue is color casts (blue, magenta, green, etc.). If you shoot RAW, these can be corrected by adjusting white balance or using Lightroom’s Color Grading tool. However, it is best to avoid them in the first place.
Many websites offer comparative tests of filters, but:
- This is not the subject of this article—I will not include such tests here.
- Tests are not always comprehensive, nor representative of all ranges within a brand.
- Manufacturers like Hoya multiply their ranges, making comparisons confusing even for experienced photographers.
- Some reviews may be biased: an article could be sponsored, or the photographer may have received free gear without disclosing it.
Some manufacturers offer antistatic coatings. For instance, I once bought a Hoya ND64 filter for 2-minute exposures at sunset. Without it, even at f/22, my shutter speed was too short, and with my ND32000 the exposures were excessively long. Unfortunately, the filter arrived covered in dust, and cleaning fibers stuck to the glass. I returned it and invested in a higher-quality filter.
Filters I Use
I primarily use 82 mm screw-in filters, which I also mount on my 77 mm lenses using step-down rings (82–77 mm). To avoid vignetting at wide angles, I always choose slim-frame filters, suitable for my Nikkor Z 14–30 mm f/4.
I previously used a Hoya ND1000 (77 mm). In bright daylight, it did not allow exposures longer than 60 seconds. I eventually replaced it with a Nisi IR ND32000, which shows no noticeable color cast.
For late afternoon, when light is too strong to shoot without a filter but too weak for an ND32000 (−15 EV), which would create excessively long exposures, I use an ND64, much better suited to these conditions.
Precautions
- On DSLRs: cover the viewfinder (using the built-in shutter or a cloth) to prevent light leaks.
- On mirrorless cameras: disable IBIS when on a tripod to avoid micro-movements.
- Switch to manual focus or disable AF to prevent focus shifts during exposure.
- Clean the lens and filter carefully: in long exposures, even tiny dust spots may appear clearly against smooth areas such as sky or water.
- Use a sturdy tripod and a remote shutter release (or self-timer) to prevent vibration.
How to Use an ND Filter
Using an ND filter requires method, especially for long exposures lasting several seconds or minutes. Steps to follow:
- Measure exposure without the filter: set framing, ISO, and aperture, and measure exposure before attaching the ND.
- Apply the filter factor: each ND reduces exposure by a given EV (see table above). For example, an ND1000 (−10 EV) turns 1/30s into a 30-second exposure.
- Use a dedicated app: to avoid mistakes, apps such as PhotoPills (available on iOS and Android) let you input initial parameters and filter type. The app will calculate the corrected exposure time.
- Ensure tripod stability: long exposures require a rock-solid setup. Avoid unstable ground, hang a weight under the tripod if needed, and trigger with a remote or self-timer.
With some preparation, ND filters are easy to use—for smoothing water, removing passersby, or creating artistic blur effects.
How to Recreate a Long Exposure Effect Without a Tripod
At the Accademia Gallery in Florence, I wanted to contrast Michelangelo’s David with the bustling crowd photographing it. My tripod was left at the cloakroom, so I positioned myself at the entrance of a side gallery, without any support.
I used a Canon 17 mm f/4 TS-E on a Nikon Z8 with an adapter. Tilting upward preserved verticals. Thanks to the Z8’s IBIS, I shot about fifty handheld exposures between 1/8s and 1s.
In Lightroom, I selected 7 one-second exposures with the best motion effects and opened them as layers in Photoshop. After auto-aligning layers, I converted them into a smart object and applied the stacking mode Mean (Layers > Stack Mode > Mean).
Back in Lightroom, I converted the result to black and white to remove distracting color spots and enhance readability. The merged crowd effect creates a sense of diffuse movement, with only David and a single visitor locked in mutual contemplation remaining sharp.
Standing still – David by Michelangelo, Accademia Gallery, Florence – Photo: © Sebastien Desnoulez
Long Exposure Examples
Click on the photos below to view them full screen.
All photos on this site are copyright © Sebastien Desnoulez, no use is allowed without prior written authorization.
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About the Author
Sebastien Desnoulez is a professional photographer specializing in architectural, landscape, and travel photography. Trained in photography since the 1980s, he covered Formula 1 and reportage worldwide before devoting himself to fine art photography focused on composition, light, and emotion. He also shares his technical expertise through practical articles for passionate photographers, particularly about Nikon Z lenses and hybrid workflows.
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