Neutral density lens filters, or ND filters, are a powerful tool for any photographer looking to expand their creative control. By reducing the amount of light entering the lens, ND filters open up a world of possibilities — from silky smooth water in landscape photography to blurred motion effects in bright daylight.
Here's everything you need to know about ND lens filters, from the different types available to the ideal situations for using them.
What is a Neutral Density Filter?
Think of an ND filter as a pair of sunglasses for your camera lens. It's a darkened piece of glass that sits in front of your lens, reducing the amount of light that reaches the sensor. This allows you to use slower shutter speeds or wider apertures for creative effects, even in bright daylight, without risking overexposure.
Types of ND Lens Filters
There are two main types of neutral density filters:
- Fixed ND filters — These have a pre-determined amount of light reduction, measured in f-stops. A 2-stop ND filter halves the light entering the lens, allowing you to double your shutter speed. Higher stop filters (3-stop, 6-stop, 10-stop) offer progressively stronger light reduction.
- Variable ND filters — These allow you to adjust the filter's density by rotating a ring, giving you a wider range of light reduction in a single filter.
Square vs Circular ND Filters
- Circular filters — Screw directly onto the front of your lens. Easy to attach and remove, making them ideal for everyday use and quickly adapting to changing conditions.
- Square filters — Held in place by a filter holder attached to your lens. They offer greater flexibility for composing your shot and are commonly used with wide-angle lenses, where circular filters can cause darkening at the corners of the image (vignetting).
When to Use a Neutral Density Filter
- Long exposures — ND filters allow slower shutter speeds, enabling creative effects like silky smooth waterfalls, streaking light trails from cars, or star trails — adding a compelling sense of movement to your images.
- Shallow depth of field in bright light — Achieving a wide aperture (and therefore a blurred background) in bright conditions can lead to overexposure. An ND filter lets you shoot wide open without blowing out your highlights.
How Many Stops Should a Neutral Density Filter Be?
- 1–2 stops — Subtle effects, or a little extra leeway in bright outdoor conditions.
- 3–5 stops — Longer exposures on overcast days, or moderate motion blur.
- 6–10 stops — Very long exposures in bright sunlight, or dramatic motion blur effects.
Take Your Photography to the Next Level
Choosing the right ND filter is an exciting step in expanding your creative capabilities. With a bit of experimentation, you'll be unlocking effects that were previously out of reach.
To learn more about other filter options, check out our Camera Lens Filter Buying Guide. Or browse our full range of camera lens filters at Ted's Cameras and find the perfect ND filter for your photography.