Use an ND filter when there is too much light for the shutter speed and aperture you want. It is useful for slow-exposure photography and outdoor video. It does not automatically improve color or make every scene look cinematic.
What changes when you fit ND
An ND filter reduces incoming light. Instead of closing the aperture or shortening the exposure, you can keep the settings that create your intended look.
For example, if a correctly exposed scene needs 1/1000 second without a filter, reducing light by three stops lets you use approximately 1/125 second at the same aperture and ISO. The filter has not brightened shadows; it has made a longer exposure possible.
How ND strength is labeled
| Light reduction | Common filter factor | Common optical density |
|---|---|---|
| 1 stop | ND2 | 0.3 |
| 3 stops | ND8 | 0.9 |
| 6 stops | ND64 | 1.8 |
| 10 stops | ND1024, sometimes rounded to ND1000 | 3.0 |
Manufacturers do not always use the same naming convention. The stated stop reduction is the clearest comparison. A label containing “ND3” can be ambiguous without knowing whether it means optical density or another shorthand.
Fixed vs variable ND
A fixed filter offers one strength. It suits a repeatable setup, such as slowing a landscape exposure by a known amount.
A variable ND lets you adjust reduction within a range. That is convenient when filming as light changes. Check its specified range and inspect the image at the wide end of your lens. Dark patterns, unevenness or color shifts can make a nominally convenient setting unusable.
We recommend a fixed ND when you can predict the exposure you need, and a variable ND when adjustment speed matters more. Check sample images and compatibility for the actual filter rather than relying only on a claimed stop range.
Choose strength from the exposure
- Set the aperture, ISO and shutter speed you want.
- Check how far the image is overexposed using the meter and highlight tools.
- Choose enough reduction to bring the exposure back into range.
- Recheck the image after fitting the filter, including corners and color.
- Remove the filter when light falls and it is no longer needed.
For video, a shutter near twice the frame rate is a common starting look, such as 1/50 at 25 fps. It is a creative convention, not a requirement for every shot.
Fit and handling matter
Check the lens’s filter-thread diameter, not its focal length. A 35mm lens does not necessarily take a 35mm filter. Step-up rings can let several lenses share a larger filter, but may interfere with a hood or storage arrangement.
For long exposures, keep the camera still and check the frame for movement you did not intend. Pair this guide with our tripod advice and exposure basics.
Technical references
Tiffen’s ND strength chart explains stop and density notation. Canon’s variable ND adapter documentation gives a concrete example of limits and color unevenness at stronger settings.
An action camera filter set
Action cameras benefit from ND filters in bright sun. The Telesin CPL and ND8/16/32 kit for the DJI Osmo Action 6 bundles a polarizer with three ND strengths. See our action camera accessories guide for the wider kit.
Frequently asked questions
What does an ND filter do?
A neutral density filter reduces light reaching the sensor. It lets you use a longer exposure or wider aperture in light that would otherwise overexpose the picture.
Is ND8 the same as eight stops?
Not in the common filter-factor notation. ND8 is three stops because it transmits one eighth of the light. Always check the maker's stop rating.
Do you need an ND filter indoors?
Usually not if light is already limited. Use ND only when you need less light to keep your chosen shutter speed and aperture.