What Are ND Filters?

Everything you need to know about ND filters

We’re happy to explain what this filter can do for your photos.

ND filters are ideal when you’re shooting outdoors. An ND filter, also known as a neutral density filter, works like sunglasses for your lens. Curious about this filter and when it’s best to use one? We’ll answer the most frequently asked questions and tell you everything you need to know about ND filters.

What is an ND filter?

ND stands for “Neutral Density.” An ND filter (also called a neutral density or grey filter) is essentially sunglasses for your lens. It’s a lens filter that reduces the amount of light entering the camera. These filters are made from darkened glass or plastic. When you place an ND filter on your lens, less light reaches your camera sensor. The result: fewer overexposed photos.

This is especially useful when you like shooting with a wide aperture or when you want to work with slower shutter speeds. Thanks to an ND filter, you can still capture sharp and properly exposed photos in these situations.

What are stops?

When talking about ND filters, you’ll often come across the term “stops.” Stops indicate how much darker or lighter your image becomes. This allows you to choose exactly how much light you want to block or double for each photo.

It’s important to know that using an ND filter also affects your aperture, shutter speed, and ISO settings. For example, you can use a slower shutter speed when photographing with an ND filter that blocks a lot of light, because light can hit the sensor for a longer period without overexposing the image.

There are useful calculations that help you determine the effect of the ND filter on your other settings. For example, the difference between aperture f/5.6 and aperture f/8 equals one stop. The same applies to shutter speed: the difference between 1/250 and 1/125 is also one stop.

Some filters come with a handy chart that helps you quickly determine the correct shutter speed when using a neutral density filter. For example, if your shutter speed is 1/200 and you attach a 4-stop ND filter to your lens, your shutter speed becomes four stops slower — in this case, approximately 1/12 second.

We understand this can seem complicated at first, but the more you practice, the easier it becomes. Who knows, maybe you’ll soon be taking photos like these too:

When do you use an ND filter?

There are several reasons why you might use an ND filter. One of the most common uses is capturing movement, such as flowing water in a waterfall or light trails from cars. When you use a neutral density filter in these situations, you can work with a slower shutter speed to create smooth, flowing effects.

In addition, you can place an ND filter on your lens when you want to use a wider aperture. In this case, the function of the filter is to prevent overexposure. This is often used in portrait photography, where you may want a shallow depth of field while still maintaining correct exposure in bright conditions.

ND filters with a fixed stop

Fixed-stop filters are the most common type of ND filter. These filters have a fixed strength. If you need a different intensity, you’ll have to switch to another ND filter. The strength is usually indicated in numbers or stops.

ND filters with a variable stop

Variable ND filters work a little differently. With this type of filter, you can adjust the strength yourself. This allows you to decide exactly how much light you want to block in each situation.

Variable filters are especially useful when shooting in changing conditions. For example, when photographing outdoors and clouds move in front of the sun, you can simply adjust the filter instead of changing to a different one.

Can you also film with an ND filter?

Yes, an ND filter can also be very useful for video recording. Just like with photography, an ND filter helps prevent overexposure while filming.

There is one important thing to keep in mind when filming with an ND filter: your shutter speed should be double your frame rate. This is exactly why ND filters are so important for video. Without one, your footage can easily become overexposed in bright conditions. An ND filter helps maintain the correct light balance while preserving natural-looking motion blur.

Long story short: all the tips and benefits of an ND filter

To wrap things up, we’ve listed the main advantages of ND filters along with some useful tips.

Benefits of ND filters

ND filters:

• reduce the amount of incoming light;
  
• can add motion blur to moving subjects;
  
• allow you to use long shutter speeds in daylight;
  
• help reduce light in specific parts of your composition;
  
• make it possible to shoot with a wide aperture (such as f/1.8).

Tips for using an ND filter

Planning to use an ND filter? Here are a few final tips:

• mainly use an ND filter in bright conditions, such as during the day;
  
• when using an ND filter, shoot in Manual (M) mode;
  
• variable filters are ideal when shooting in changing conditions;
  
• when filming with ND filters, make sure your frame rate and shutter speed are correctly balanced.

Short but powerful: ND filters

Curious why every photographer should own an ND filter? Our video team explains it all in detail in this video: