Buying guide

ND Filter for Video: Stops, Variable vs Fixed, Thread Sizes

The 180-degree shutter rule, how many stops daylight needs, variable ND and the cross pattern, IRND, thread sizes for popular lenses and when to use step-up rings.

Updated 27 September 2026 6 min read By Electronic Australia

Short answer An ND filter for video lets you keep the shutter at about double the frame rate (1/50 for 25p) and the aperture wide in daylight. In direct midday sun at ISO 100, shooting f/2.8 at 1/50 needs roughly 6 stops of ND. A 2 to 5 stop variable ND suits run-and-gun work, while fixed or IRND filters suit controlled shoots and dark fabrics. Buy for your largest lens thread and step the others up.

Choosing an ND filter for video comes down to four decisions: how many stops you need, whether a variable or fixed filter suits the way you work, whether infrared contamination will matter, and what thread size to buy. This guide works through each one, then points to filters in our neutral density filter range.

Why an ND filter for video matters: the 180-degree rule

The 180-degree rule is a cinematography convention: set the shutter to roughly double the frame rate. That gives each frame a natural amount of motion blur, so movement looks smooth rather than choppy. PolarPro and Hoya both describe it this way, and Hoya adds that a shutter far faster than the frame rate produces jarring, separated motion in a video sequence.

Frame rate	Shutter speed for 180 degrees
24p	1/50 (1/48 exact)
25p	1/50
30p	1/60
50p	1/100
60p	1/120

Photographers deal with bright light by raising the shutter speed. Video shooters cannot do that without breaking the rule, and stopping the lens down loses the shallow depth of field many people bought a fast lens for. An ND filter is the only control left: it cuts light evenly across the frame without changing colour (in a good filter) or depth of field.

How many stops of ND filter do you need

Reading ND numbers

Filters are labelled in two ways. The ND factor (ND8) tells you how many times the light is reduced. The optical density (0.9) goes up by 0.3 for each stop.

ND factor	Density	Stops	Typical use
ND2	0.3	1	Fine trim indoors or at dusk
ND4	0.6	2	Overcast days
ND8	0.9	3	Open shade, cloudy bright
ND16	1.2	4	Soft sun, stopped down a little
ND64	1.8	6	Direct sun at f/2.8
ND1000	3.0	10	Long exposure stills, not everyday video

Stops for Australian daylight

The sunny 16 rule gives a useful starting point. In direct sun at ISO 100, a correct exposure is about f/16 at 1/100. Slow the shutter to 1/50 for 25p and the equivalent is about f/22. From f/22 to f/2.8 is six stops, so you need roughly ND64 or a 6-stop setting. Open to f/1.8 and you need close to 7 stops. Stop down to f/4 and 5 stops will do.

Two things push the number higher. Bright sand, water and pale concrete reflect extra light, and many cameras' log profiles start at a higher minimum ISO than 100. Each doubling of ISO adds one stop to the ND you need, so a profile that starts at ISO 800 needs three more stops than the table above. Haze, cloud and late afternoon light pull the number down.

Variable ND vs fixed ND

A variable ND is two polarising layers in one frame. Turning the front ring changes how much light gets through. A fixed ND is a single piece of glass with one density.

	Variable ND	Fixed ND
Speed of adjustment	Turn a ring, no filter change	Swap or stack filters
Range	Usually 2 to 5 or 6 to 9 stops in one filter	One strength per filter
Colour and evenness	Can shift at the dark end	Generally more consistent
Cross pattern	Possible near maximum	No
Suits	Events, travel, vlogging, gimbal work	Interviews, narrative, repeatable setups

The variable ND cross pattern

Because a variable ND works by crossing two polarisers, pushing it to its darkest setting can produce an uneven dark X across the frame. Hoya states this directly for its Variable Density II: near or at maximum density a cross-like dark pattern appears and cannot be removed, as a property of variable ND filters. Wide lenses make it more visible.

Manufacturers deal with this in two ways. Some limit the range. NiSi says its True Color ND-Vario covers 1 to 5 stops with no cross polarisation artefact at its maximum and no vignetting at 16mm full-frame equivalent. Others split the range across two filters, which is why you will see variable NDs sold as 2 to 5 stop and 6 to 9 stop versions. Tiffen also notes that the marks between minimum and maximum on its variable ND are reference points, not calibrated stops, so use the camera's meter or zebras rather than counting marks.

Variable ND filters for video

IRND: when infrared becomes a problem

Digital sensors are sensitive to some infrared light. Traditional ND filters were designed in the film era, when only visible light mattered, so many cut visible light without cutting infrared by the same amount. With heavy ND, infrared makes up a larger share of what reaches the sensor. The result is often called IR pollution: black fabrics can look pink, reddish or brownish, and the whole image can drift warm.

An IRND filter adds infrared blocking to the ND so both are cut together. Tiffen goes a step further with its NATural ND line, which it says blocks IR, UV and visible light for a more neutral image. Consider an IRND if you often film dark suits or black fabric with heavy ND. How much it matters varies by camera and filter, so test your own body before a paid job.

Fixed ND, IRND and ND kits

Browse more in variable neutral density and solid neutral density, or the full NiSi range.

What size filter do I need

The filter thread size is printed on the front of the lens barrel or the inside of the lens cap, marked with a diameter symbol. Manufacturer specifications for some popular lenses:

Sony FE 24-70mm f/2.8 GM and GM II: 82mm
Sony FE 24-105mm f/4 G OSS: 77mm
Sigma 18-50mm f/2.8 DC DN Contemporary: 55mm
Sony E PZ 16-50mm kit zoom: 40.5mm

ND filter for Sony 24-70

Both versions of the Sony FE 24-70mm f/2.8 GM take 82mm filters. Because 82mm is also the largest thread among the lenses most hybrid shooters carry, an 82mm variable ND is a common anchor for a kit.

Step-up rings

A step-up ring screws into a smaller lens thread and presents a larger one, so a single 82mm filter can serve a 67mm, 72mm or 77mm lens as well. It does not change focal length or aperture, and it saves buying the same variable ND several times over. A few cautions:

Use one slim ring rather than chaining several together.
Check the widest focal length on wide zooms, where thick frames and stacked filters are most likely to darken corners.
Avoid step-down rings, which put a smaller filter on a larger lens and invite vignetting.
Lens hoods usually will not fit over a stepped-up filter.

Step-up rings to 82mm

See all sizes in our step-up rings category.

Magnetic ND systems

If you swap filters often, a magnetic system replaces threading with an adaptor ring that stays on the lens and filters that snap on. It costs more to set up but speeds up changes, especially when stacking an ND with a mist filter. Our guide to magnetic filter systems compares NiSi JetMag Pro, Freewell, PolarPro Helix and screw-in options in detail. For gimbal cameras with built-in lenses, see the ND section of our DJI Osmo Pocket guide.

Questions

How many stops of ND do I need for video in sunlight?

For f/2.8 at 1/50 and ISO 100 in direct midday sun, about 6 stops, based on the sunny 16 rule. Wider apertures, reflective surroundings and log profiles with a higher base ISO push that toward 7 to 9 stops. For overcast days, 2 to 4 stops is usually enough.

Is a variable ND good enough for professional video?

Many professionals use them for events, documentaries and gimbal work because they save time. The trade-off is possible colour shift and the cross pattern at the dark end. Staying inside the filter's marked range, or choosing one designed to avoid the cross pattern, avoids most problems. Fixed NDs remain more consistent for controlled shoots.

Do I need an IRND filter?

Only if you use heavy ND and film subjects where infrared shows up, such as black fabric, which can turn pink or brownish. With light ND the effect is usually small. Test your camera with a black jumper in sun, with and without the filter, to see whether it matters for your work.

Can I use one ND filter on all my lenses?

Yes, with step-up rings. Buy the filter to fit your largest lens thread, often 82mm, and add a ring for each smaller lens. Check for dark corners at the widest focal length, and use a single ring rather than stacking several.

Sources

Specifications and background were checked against these pages when the guide was last updated. Always confirm compatibility on the product page before ordering.

ND Filter for Video: Stops, Variable vs Fixed, Thread Sizes

Why an ND filter for video matters: the 180-degree rule