What is an ND Filter and When to use the ND filter?
Have you ever wondered how photographers capture dreamy smooth waterfalls? Or how they smooth out the water in seascapes? One of the secrets is using a Neutral Density filter. If you’re thinking of buying or using ND filters to create long exposure effects, and you want to know the basic knowledge of it, then this tutorial is for you.
What is an ND Filter?
ND filters(Neutral Density Filters) are designed to reduce the amount of light that entering the camera sensor. It's basically a pair of sunglasses to your camera. With less light entering the camera lens, a longer exposure or a wider aperture can be achieved.
Photo@Adrián González López
What do ND filters do?
With an ND Filter, you have a larger degree of control over the exposure in an image. You can shoot the stunning motion blur images that we are unable to see with our eyes.
Here’s an example of two similar shots, The first without an ND filter and the second one without ND filter:
Photo@Federico Pasinetti With an ND filter
Photo@Federico Pasinetti With an ND filter
When to use the ND filter?
1: The Motion Blur Effect
Shooting the flowing water particularly the waterfall is a time when you want to use an ND filter. Capturing the moving water with slow shutter speeds((1/15th of a second and longer) can create a silky effect. But it is basically impossible to achieve on a bright sunny day even with the smallest aperture and the lowest ISO. In this situation, applying a proper ND filter is equivalent to stopping down one or more additional stops, thus leading the slower shutter speed and dreamy motion blur effect.
2: Shallow Depth of the Field
If it's the middle of the day and you want to capture a nice shallow depth of field you'll need to have the aperture wide open. An ND filter can help you to achieve a shallow depth of field even under full sunlight.
Examples of this use include:
- Blurring water motion (e.g. waterfalls, rivers, oceans).
- Reducing the depth of field in very bright light (e.g. daylight).
- When using a flash on a camera with a focal-plane shutter, exposure time is limited to the maximal speed (often 1/250th of a second, at best), at which the entire film or sensor is exposed to light at one instant. Without an ND filter, this can result in the need to use f/8 or higher.
- Using a wider aperture to stay below the diffraction limit.
- Reduce the visibility of moving objects.
- Add motion blur to subjects.
- Extended time exposures.
Why do I need an ND filter?
Without an ND filter Use Contrast With an ND filter
Without ND filter With ND filter