A neutral density (ND) filter reduces the light reaching your sensor without changing color, which lets you use shutter speeds of several seconds or minutes in bright daylight. Mount the camera on a tripod, compose and focus without the filter, attach it, and then lengthen the shutter speed to match the filter’s strength.
Choosing a Strength
ND filters are labeled in stops, optical density, or filter factor, so check the label on your filter. Each stop halves the light. These are general guides for sunny conditions.
| Filter strength | Typical effect |
|---|---|
| 3 stops | Slightly softer water at moderate speeds |
| 6 stops | Silky streams and gentle cloud movement |
| 10 stops | Multi-minute exposures that smooth the sea and streak clouds |
A variable ND filter covers a range in one piece of glass, but some can show uneven darkening or color shifts at the strongest setting. A fixed filter avoids that issue.
Step by Step
- Set the camera on a sturdy tripod and turn off lens stabilization if the lens manual recommends it.
- Compose your shot and focus carefully, using autofocus or live view magnification. Then switch the lens to manual focus so it does not hunt after you attach the filter.
- Meter the scene without the filter in aperture priority at your base ISO and a mid-range aperture, often f/8 to f/11 as a baseline.
- Note the shutter speed the camera suggests.
- Attach the filter and switch to manual mode.
- Calculate the new shutter speed by doubling the original once for each stop. For example, 1/60 second with a 6-stop filter becomes roughly 1 second.
- For exposures beyond the camera’s longest setting, use Bulb mode with a remote release or an interval timer.
- Take the shot, check the histogram, and adjust the time up or down.
Practical Details
- Light leaks: with a dark filter, light can enter through the viewfinder on some cameras. Cover the eyepiece if the manual suggests it.
- Color casts: very strong filters sometimes add a tint. Shoot raw and fix white balance later.
- Wind: a breeze can shake the tripod during long exposures, so lower the center column and hang a bag from the hook.
- Subjects: moving water, clouds, crowds, and tall grass respond well. Static scenes gain little.
FAQ
Do I need a tripod?
Yes, for any shutter speed longer than you can hold steady by hand. A stable tripod is the most important companion to the filter.
Why is my image soft with the filter on?
Possible causes include focus shifting after you attach the filter, movement of the tripod, or a low-quality filter. Refocus before attaching and check results at 100 percent.
The Short Version
Pick an ND strength that fits the time you want, focus first, then add the filter and extend the shutter speed by one doubling per stop. Use a sturdy tripod and a remote release, and check the histogram after each frame.
