lovelifey: [Photography] Neutral Density Filters: Everything You Need to Know

The post Neutral Density Filters: Everything You Need to Know appeared first on Digital Photography School. It was authored by Andrew S. Gibson.

neutral density filters the essential guide

What are neutral density filters, and how can they improve your photography?

In this article, I share everything you need to know about ND filters, including basic instructions, specific gear recommendations, plus some helpful advice along the way.

So if you want to know how to use a neutral density filter, when to use an ND filter, or why to use an ND filter, you’ve come to the right place.

Let’s dive in, starting with a simple definition:

What is a neutral density filter?

A neutral density filter blocks light, which is why it’s sometimes referred to as sunglasses for your camera. The result? Less light passes through the lens to reach the camera’s sensor.

In other words, a neutral density filter is essentially a dark piece of glass that goes in front of (or behind, in some special circumstances) your lens.

Different neutral density filters offer different levels of light-blocking power, generally measured in stops of light. Typical ND filter strengths are one stop (written as “0.3” or “ND2”), two stops (written as “0.6” or “ND4”), three stops (written as “0.9” or “ND8”), six stops (written as “1.8” or “ND64”) and ten stops (written as “3.0” or “ND1024”).

Some manufacturers even make neutral density filters that block 16 stops of light or more, although these are specialty items and infrequently used by the average photographer (professional or otherwise).

Note that the higher the ND filter strength, the more light that gets blocked. So a ND2 filter, which blocks one stop of light, pales in comparison to an ND64 filter and its six-stop light-block capabilities.

The photo below shows a ten stop neutral density filter mounted on the front of a lens. As you can see, the filter is nearly opaque; once it’s added to your setup, you won’t be able to see through the camera viewfinder.

Why should you use ND filters in your photography?

ND filters block light, yet photographers generally want more light, not less. So why should you consider using an ND filter?

Well, as it turns out, more light is good…most of the time. Occasionally, though, you’ll find that you have too much light to work with, which is where ND filters come in handy.

Specifically, you can use neutral density filters in two helpful ways:

To achieve a wide aperture in bright sunlight
To slow down your shutter speed in the daytime

Let’s take a look at each of these effects in turn:

Using ND filters to achieve a wide aperture

As you may be aware, wide apertures create beautiful blurry background bokeh that makes the subject pop off the page (portrait photographers love this!).

Unfortunately, when the light is strong, a wide aperture will let in too much light, resulting in overexposure. So the blur-happy photographer is either forced to wait until the light dies down, or must use a narrow aperture and sacrifice their beautiful wide-aperture backgrounds.

Except there’s another option:

The ND filter.

It’ll fit over the lens and block out some of the bright light. That way, you can use a wide aperture to achieve your desired blur effect without overexposing the shot.

Using ND filters to slow down your shutter speed

Landscape photographers use long exposures to create blurry, stretchy clouds, ethereal atmosphere, and still water.

But to create a long exposure, you generally need a shutter speed of a second or longer, which is pretty much impossible to do in the middle of the day without dramatic overexposure.

That’s where ND filters come in. You can use your ND filter to block the light, which in turn allows for beautiful long exposures of landscapes.

In fact, I’d say that this function – for long exposures in the landscape – is probably the most common reason to see an ND filter on a photographer’s lens.

For example, this photo was taken with a 1/125s shutter speed and no ND filter:

But I wanted blur in the water, so I added an ND filter and turned that exposure time into a whopping 210 seconds. Here’s the resulting shot:

When should you use ND filters?

As you’ve probably gathered, neutral density filters are especially useful for portrait photography, especially portraits done in bright sunlight. They’re also highly useful for landscape photography – if your goal is to blur a moving subject, an ND filter can probably make it happen.

However, you can certainly use ND filters in other scenarios. For instance, an architectural photographer might want to blur the clouds when photographing buildings or even home exteriors. An abstract photographer might want to blur water when photographing on the beach. And a videographer might want to keep their aperture wide while filming in the sun.

In each of the above cases, an ND filter is the easiest way to achieve the photographer’s artistic goals.

Neutral density filters vs graduated neutral density filters

There are two popular types of neutral density filters:

Standard ND filters.

And graduated neutral density filters (also known as “GND filters”).

So what’s the difference?

Neutral density filters block light evenly across the frame. Graduated neutral density filters, on the other hand, block light across just part of the frame. Half the filter is clear, half is opaque, and you get a graduated area in between.

GND filters are designed to handle uneven exposures. If you’re photographing a sunset with a bright sky and a dark foreground, the darker portion of the GND filter will dial back the sunset, while the lighter portion will do nothing. That way, you get a well-exposed sky and a well-exposed foreground in the same photo. Make sense?

The photo below shows a two-stop Lee graduated neutral density filter in a square filter holder. The top half of the filter is dark (to block light) and the bottom is clear:

In general, graduated filters are used by landscape photographers to deal with tricky sky-foreground lighting conditions. And unlike neutral density filters, their purpose isn’t to slow down the shutter speed or widen the aperture – instead, it’s simply about blocking out a too-powerful sky.

How to use neutral density filters: the basics

Now I’ll share a quick ND filter tutorial for portrait and landscape photography.

ND filters for portraits

Using ND filters to create wide-aperture portraits is simple.

Just choose a relatively weak ND filter (in the 1-stop to 3-stop range). Mount it in front of your lens. And take photos the way you normally would, except with greater latitude when choosing the aperture.

If you still can’t get the aperture you’re after, then you can always swap out your original ND filter for a stronger option.

Just make sure to watch the light carefully. If the sun goes behind clouds, you may need to take the filter off the front of your lens to get the shots you want.

ND filters for landscapes

Using an ND filter to capture slow-shutter landscape photos can take careful technique, especially if you’re using a strong filter (e.g., 10 stops or 16 stops).

As mentioned above, it’s tough to see through a powerful ND filter. So you’ll need to identify your composition and set your point of focus before adding the filter. (You may also want to determine the proper exposure prior to adding the filter, then adjust the shutter speed to compensate once you’ve added the filter to your lens).

Make sure you’ve mounted your camera to a tripod (you don’t want to end up with any camera shake!). Then trigger the shutter using a remote release or your camera’s self-timer function.

The neutral density filters I use

There are many neutral density filters to choose from – so how do you know which ones to buy?

Ultimately, you have to decide how much you want to spend (some ND filters are quite expensive!), then look at the options. But I can start by telling you which filters I own and recommend.

You see, I use an ND filter kit, the circular Formatt Hitech 72mm Firecrest Joel Tjintjelaar Signature Edition Long Exposure Kit. It contains three neutral density filters, with strengths of 3, 6, and 10 stops.

You can also stack two filters together to block 9, 13 or 16 stops of light.

Note: if you plan to use your filters on multiple lenses, buy the filter size you need for the largest lens, and get step-down rings to adapt the filters to fit the smaller lenses – or get the square drop-in filter kind instead.