An ND filter is a grey filter that blocks light so you can use a longer shutter speed in daylight. Enter your shutter speed without a filter and pick your ND strength to get the correct shutter speed with the filter, from ND2 to ND1000.
Common ND values
| Filter | Stops | New time |
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What filter types exist?
An ND filter is one of about a dozen categories. Below is an overview of the filters you will encounter in practice, what they do and when they are useful. Click through to the photo thesaurus for the in-depth explanation per filter.
Light reduction
- ND filter
- Blocks light without affecting colour. Long shutter speeds in daylight, wide aperture in bright light.
- Variable ND (VND)
- ND with a stepless rotating ring. Video and run-and-gun work. One filter for many situations.
- Graduated ND (GND)
- Half dark, half clear. Darkens sky or horizon. Landscape with big exposure gaps between sky and land.
Light quality
- Polariser (CPL)
- Blocks polarised light. Cuts reflections, deepens blue skies, saturates colour. Landscape, water, glass. Does not work on metal.
- UV filter / Protective filter
- Optically clear. Protects the front lens element. Beach, desert, rain. As sacrificial glass.
- Black Mist / Pro Mist
- Diffuses highlights, lowers contrast. Cinematic glow. Portrait, video, evening scenes with point lights.
Creative / experimental
- Star filter / Cross filter
- Turns point lights into 4-, 6- or 8-ray stars. Christmas markets, city lights, events.
- Streak filter (anamorphic)
- Horizontal light streaks around bright sources. Video and cinematic stills. Deliberate choice, not for every shot.
- Infrared filter (IR)
- Blocks visible light. White leaves, black sky. Surreal landscapes. Only works on IR-sensitive or converted cameras.
ND Filter Calculator: how it works
The ND filter calculator tells you exactly what shutter speed to use after mounting an ND filter on your lens. Use it whenever you shoot long exposures, whether that is silky waterfalls, blurred waves, or slow-moving clouds. Enter your base exposure, pick your filter strength, and get the corrected shutter speed straight away.
How ND filters change your exposure
An ND filter cuts the amount of light reaching the sensor without affecting color. Each stop of light reduction doubles your shutter speed. An ND2 blocks one stop, an ND1000 blocks ten stops, making your shutter speed 1024 times longer than the base exposure.
In practice that means a base exposure of 1/250s becomes just over four seconds with an ND1000. Calculating that by hand in the field is where mistakes happen. The calculator handles the math so you can focus on the shot.
Practical situations where this tool saves time
Long exposure photography is the most obvious use case: smoothing out water, streaking clouds, or emptying a busy street of people. But videographers working at a fixed shutter speed of 1/50s also run into situations where an ND filter is the only way to control exposure without touching aperture or ISO.
The calculator covers every common filter strength from ND2 to ND1000. Type in the shutter speed you measured without the filter, select the ND value, and read off the result. No more counting stops on your fingers in the dark.
Frequently asked questions
How many stops does an ND1000 filter block?
An ND1000 blocks ten stops of light. A base shutter speed of 1/125s becomes roughly eight seconds with that filter in place.
How do I calculate exposure when stacking two ND filters?
Add the stops of both filters together and use that combined value. An ND8 (three stops) stacked with an ND64 (six stops) behaves like a nine-stop filter, equivalent to an ND512.
Why is my long exposure still overexposed after using the calculated shutter speed?
The most common cause is measuring your base exposure with the filter already on the lens. Remove the filter first, meter the scene, then enter that reading into the calculator.