Why use a Neutral Density (ND) filter?

“The goggles, they do nothing!”

Sometimes you have too much light, and that’s where Neutral Density (or ND) filters come in. Neutral Density filters are designed to simply reduce the amount of light that gets to your camera. They are dark filters that typically come in 1, 2 or 3 stop reduction increments, and are most often used outdoors under bright sunny conditions.

With most shooting situations (especially indoors or under low light) the issue is the opposite, so it’s hard to imagine needing less light. Typically, you need more light, faster shutter speeds, etc. That’s why ND filters are often used for landscape photography, where during a bright sunny day, light is in abundance. This may simply be because of the light amount, or because you have light hitting off a highly reflective surface such as sand, water, or snow and ice.

Left side with no ND filter, Right side with an ND4 filter.

Reduce the Light Intensity

Maybe you want to simply reduce the amount of light in the picture. All cameras have a maximum shutter speed they can attain, and every lens has a widest aperture they can open up to. If you have too much light, it can strain these limits. Also, every lens has a sweet spot which you may want to shoot in, which could require less light to achieve.

Slower Shutter Speed

If you’ve ever shot a picture of running water, you’ve likely tried using a slower shutter speed to indicate motion. There are a variety of other scenarios where using a slow shutter speed may be the technique required to get the shot, but you can only slow down the shutter speed if you can reduce the amount of light. If your aperture is already at it’s minimum, an ND filter will let you cut out some light so you can achieve this.

Wider Apertures

Perhaps you want a low depth of field in your picture, or (as above) you’re looking to shoot at your lenses optimum aperture for the best sharpness. If you have too much light in the scene, the camera will struggle to not blow out the image at wider apertures, so an ND filter will help you out immensely here.

Graduated ND Filters

Finally, you can buy graduated ND filters which go from dense (dark) to light in a gradient pattern on the filter. These are handy when only a portion of the image is bright (like the sky) and a portion is darker (like the ground). It will help to achieve exposure balance.