Long-exposure shots are relatively easy to take at night with a DJI drone since their cameras are stabilized. Just set a low shutter speed and press the shutter button. If you are capturing cars, boats, or any other illuminated objects moving at night, you will end up with some cool light trails like in the picture below.
But if you’ve tried taking a long-exposure shot during the day, you know that once you’ve set the smallest aperture and lowest ISO possible, increasing your shutter speed will inevitably overexpose your shot. This is where ND filters come in handy.
What is an ND Filter?
A Neutral-Density Filter, or ND filter, is likened to "sunglasses"for your camera. The primary purpose is to control the amount of light that is entering the camera lens. Under bright sunlight, an ND filter allows photographers more leeway in selecting an aperture and shutter speed by preventing overexposure.
Using ND filters
Here's a more detailed breakdown of what ND filters can do:
- Long Exposure Photography:
ND filters allow photographers to use longer shutter speeds in bright light without overexposing the image.
This can create a variety of effects, such as turning a bustling city square into an ethereal ghost town, blurring flowing water in daylight into a smooth, magical stream, or creating silky clouds against a static landscape.
ND filters can help mitigate the issues of light pollution when shooting celestial bodies.
- Shallow Depth of Field:
ND filters allow photographers to use a broader aperture setting in bright conditions, enabling a narrow depth of field for a pronounced bokeh effect, without the risk of overexposure.
- Video Cinematography:
For filmmakers, ND filters are essential to maintain the preferred shutter speeds to obey the "180-degree shutter rule". This rule results in a more cinematic look with proper motion blur.
Device: DJI Air 2S | Aperture: f/2.8 | Exposure: 1/50s | ISO: 100 | Filter: ND 512
- Color Saturation And Contrast:
In high-contrast scenarios, like seascapes or snow, ND filters can help balance the image's brightness range, improving color saturation and overall contrast.
Choosing ND Filters
DJI has different official ND filters for their drones and cameras, like ND4, ND8, ND16, ND32, ND64, ND128, and more.
The number associated with an ND filter indicates that how much light enters the lens in terms of a fraction.
- ND4 reduces light by 1/4. An ND4 filter can reduce 2 stops of light, allowing you to slow the shutter speed from 1/100s to 1/25s.
- ND8 reduces light by 1/8. An ND8 filter can reduce 3 stops of light, allowing you to slow the shutter speed from 1/200s to 1/25s. This one cuts 3 stops of light and is good for slight motion effects, like smoothing out rushing water.
- ND16 reduces light by 1/16. An ND16 filter can reduce 6 stops of light, allowing you to slow the shutter speed from 1/400s to 1/25s.
- ND64 reduces light by 1/64. An ND64 filter can reduce 4 stops of light. It's often used to blurred motion effects in bright daylight.
Please note that we recommend only using official DJI ND filters, as they are specially designed to work well with the gimbal camera’s center of gravity.
Choosing the right ND filter depends on your goals for the image and the conditions in which you're shooting. Here are some factors you should consider:
- Light Conditions:
If you're shooting in bright daylight and want to use a wide aperture for shallow depth of field, a stronger ND filter may be beneficial. Alternatively, if you're shooting long exposures at dusk or dawn, a lighter ND filter might be more appropriate.
- Shutter Speed:
If you want to create blur, such as water flowing over a waterfall or clouds moving across the sky, you'll need a longer exposure, which generally requires a stronger ND filter.
- Subject Motion:
If you're photographing a moving subject and don't want motion blur, a lighter ND filter will let you use a faster shutter speed.
Example
The photo below was taken with the Phantom 4 Pro and with the lowest ISO and smallest aperture possible. By reducing the shutter speed here, one risks overexposing the shot.
In addition to using ND filters for daytime water photography, they can also be used to take better urban landscape shots.
The shot below was taken with a relatively fast shutter speed. It looks a bit stiff and unnatural. The cars and people are moving, but there’s very little motion blur.
With an ND filter, we can lengthen the shutter speed and create some motion blur. Motion blur can give your photos a more lively and active feel, like the one below.
The screenshot below was taken with an ND16 filter attached. With ISO and aperture remaining the same, and the shutter speed can be set to 1/12.5 seconds.
If you used a weaker ND filter in this situation, you couldn’t achieve the same level of motion blur. However, if you chose a stronger ND filter, too much light would be kept out, your image would be underexposed, and your ISO value would need to increase accordingly.
So what ND filter you should choose depends on the amount of light around you and the effect you want to achieve.
Device: DJI Air 2S | Aperture: f/2.8 | Exposure: 2s | ISO: 400 | Filter: ND 4