There are lots of different accessories and add-ons that you can use along with your camera. Often, it can be difficult to know what might be useful to add a useful technique to your kit. One accessory that can be overlooked by photographers is the neutral density filter. For some, neutral density filters may seem mysterious in their use or too specialized. It can’t hurt to familiarize yourself with this very useful accessory. Although the neutral density filter is something that is found in the camera bag of many a landscape photographer, any photographer can benefit from understanding what the neutral density filter does and techniques to use it effectively. You may find that there are situations where a neutral density filter can work for you. The rest of this article will give a brief guide on how to use neutral density filters in your photography.
What is a Neutral Density Filter?
Neutral density, or ND, filters are glass or plastic filters screwed onto or placed in front of a camera lens. A neutral density filter does nothing more than affect how much light reaches the lens. Think of the neutral density filter as performing in much the same way as sunglasses or tinted windows. The darkened filter means less light through the lens and therefore less light reaching the camera’s sensor or the film plane. Neutral density filters can be screwed onto the front of the lens or used as a sheet that fits in a holder. Also, ND filters come in several types.
ND Filter – a darkened glass or plastic filter. Comes in varying strengths.
Graduated – graduated ND filters will be darkened on only part of the filter and transition to clear glass or plastic. Graduated ND filters also come in varying strengths.
Because an ND filter controls light, it also controls exposure. You will need to compensate the exposure time according to the strength of the ND filter. It is not as difficult as ou might think. You will meter your scene without the filter in place to determine exposure, then do the math depending on the strength of the filter.
ND filters are categorized by density.
|Amount Light Is Reduced
EXAMPLE: A 1-stop ND filter will halve the amount of light and therefore the exposure so a 1/8000 of a second exposure becomes 1/4000 of a second. A 2-stop ND filter means 1/8000s becomes 1/2000x. A 10-stop ND filter reduces a 1/8000s exposure to 1/80s.
When can a Neutral Density Filter Be Useful?
ND filters are commonly used in landscape photography. Creating waterfall and beach photographs where the water appears smooth, glass-like, or mist-like is made possible by using ND filters. Using an ND filter to extend the exposure into several seconds is enough to achieve this effect.
An ND filter can also be useful in urban landscape photography. Often crowds and traffic make it difficult to capture some scenes. Using an ND filter to achieve very long exposure times will effectively make people “disappear” from the photograph. Due to the extended exposure times when using ND filters in this way using a remote trigger, a tripod, or other very stable base is necessary to avoid camera shake. For DSLR users eliminating “mirror slap” by engaging mirror-lockup can also help. Image stabilization can also introduce an amount of shake as well so consider turning it off.
An ND filter can also be useful in portrait photography though this is not as common. Achieving a shallow depth-of-field in very bright daylight is limited by the camera’s highest available shutter speed. When the shutter speed isn’t fast enough to achieve the proper exposure, you have to increase your f-stop, increasing your depth of field. Using a 2 or 3-stop ND filter will allow shooting at wider apertures in brighter light, meaning shallower depth-of-field.
Hopefully, this article has provided you with an understanding of the neutral density filter and where it can be used effectively. We covered what the neutral density filter is and what it does, and the different options available. Now, it’s down to you. With plenty of available options to choose from, trying out shooting with a neutral density filter is an easy experiment. Don’t be afraid to get creative and try different things, you might be surprised by the results. I hope you can find creative and rewarding ways to use neutral density filters in your photography.