Photography filters are an essential tool for any photographer looking to enhance and transform their images. Filters allow you to control how light enters the camera lens and can be used to create a variety of special effects and correct issues like color casts or excessive brightness.
One popular type of filter is the neutral density or ND filter. ND filters reduce the amount of light entering the lens evenly across the color spectrum. This allows you to use slower shutter speeds in bright lighting conditions to achieve effects like motion blur on flowing water or car light trails at night.
What is a grey lens filter?
A grey lens filter, sometimes called a grey neutral density filter, is a type of ND filter. It reduces all wavelengths of visible light evenly, resulting in a neutral grey look when viewing through the filter.
Grey ND filters come in different densities, which refers to how much light they block. The higher the density number, the darker the filter and the more light it will absorb. For example:
- ND2 filter – 1 stop of light reduction
- ND4 filter – 2 stops of light reduction
- ND8 filter – 3 stops of light reduction
Each stop of density cuts the amount of light in half. So an ND8 filter will allow only 1/8th of the light to pass through compared to no filter.
Benefits of using a grey lens filter
There are several advantages of using a grey neutral density filter in photography:
- Allows slower shutter speeds – As mentioned above, cutting the light with an ND filter means you can use slower shutter speeds to achieve motion blur and other creative effects, even in bright daylight.
- Reduces depth of field – Using a slower shutter also allows you to open up your aperture wider. This decreases depth of field, blurring the background for a more professional, portrait look.
- Levels exposures – ND filters help balance exposures between bright skies and darker foregrounds for well-exposed landscape and cityscape photos.
- Lets you use flash in bright light – They allow you to use wider apertures with flash in bright lighting when you would otherwise exceed your flash sync speed.
- Protects lenses – A grey filter also protects the front element of your lens from dust, moisture and other potential damage when outdoors.
When to use a grey ND filter
Here are some common situations where using a grey neutral density filter can help:
- Landscapes – When shooting scenic vistas with a bright sky and darker land or water, an ND grad filter helps balance the exposure.
- Waterfalls and rivers – Using a grey ND filter allows you to achieve silky, misty water effects by slowing down the shutter speed.
- Seascapes and ocean waves – Again, slowing the shutter with an ND filter creates beautiful blurred effects on moving water.
- Cityscapes and traffic – Light trails from cars at night are only possible with a slow shutter enabled by an ND filter.
- Portraits outdoors – An ND filter allows you to open up the aperture for blurred backgrounds and flash work.
- Video – ND filters help maintain proper exposure when filming outdoors, allowing lower frame rates and shutter speeds.
How to use a grey ND filter
Using a grey neutral density lens filter is straightforward:
- Attach the grey ND filter to the front of your lens using the filter threads.
- Set your camera to manual mode and meter the exposure without the filter.
- Calculate how many stops of light reduction you need based on the filter density.
- Adjust your settings – reduce the shutter speed by the number of stops needed for the filter.
- Optionally, open up the aperture to reduce depth of field.
- Take the photo with the slower shutter speed enabled by the ND filter.
The effect will be immediately visible on your camera’s LCD. Use Live View mode to preview the motion blur or long exposure effect in real time.
Keep in mind you may need to use a tripod to avoid camera shake at slower shutter speeds. An ND filter also gives you flexibility to use wider apertures and lower ISOs for the best image quality.
Choosing the right grey ND filter density
Choosing the appropriate grey ND filter density for the situation involves some estimation and experimentation. Here are some guidelines:
| Lighting Situation | Recommended ND Filter Density |
|---|---|
| Bright sunlight | ND8 or ND16 filter |
| Moderate sunlight | ND4 or ND8 filter |
| Heavy overcast | ND2 or ND4 filter |
You may need to stack multiple ND filters together for very bright situations that require more light reduction. Always check your test shots and adjust the density as needed.
Variable ND filters
Variable ND filters offer the versatility of using different densities with one filter. They have two rotating polarizing elements – adjusting the rotation controls the density from around 1 to 5 stops of light reduction.
While variable NDs provide added convenience, some disadvantages include potential vignetting when rotated and an “X” pattern that can appear. Non-variable solid ND filters generally offer better image quality.
Conclusion
In summary, grey neutral density filters are invaluable accessories for controlling light and motion in photography. They allow creative techniques like silky water and blurred backgrounds by reducing light evenly across the spectrum.
Look for grey ND filters when shooting outdoors, whether landscapes, cityscapes, water motion or other scenes with mixed lighting. With practice, you can learn to quickly estimate the appropriate density and dial in great exposures.
Along with producing beautiful long exposure effects, grey ND filters also protect your front lens element. Investing in a high-quality grey neutral density filter kit will give you the ability to transform bright, harsh lighting into soft, creamy dreamscapes.