How and Why Do You Use an ND Filter!
Sometimes, reducing aperture size or choosing a faster shutter speed may give you a proper exposure, but ruin the picture. That’s when the ND Filter comes to the rescue.
Above: Only fast shutter speed was possible in this scene at left, but the photographer wanted to show the flow of fusion, right. A ND filter let him slow down the shutter speed.
The ND filter, also known as a Neutral Density Filter (available at Adorama), is designed to give you more control over exposure and allows you to use wider apertures in bright light when you need a longer exposure. For instance, it may be too bright for a long exposure when photographing the motion of the ocean (see photos above) but adding the right ND filter reduces the light hitting your camera’s sensor, allowing you to slow down the shutter speed while keeping the aperture consistent.
Adorama carries a complete line of Neutral Density filters. Visit the Neutral Density Filter Department at Adorama.
ND filters are color-neutral: The dyes used to make the filter have no color whatsoever, so they will not affect the color balance of any scene. They are an essential tool especially for landscape photography.
The Advantage of Rectangular ND Filters
But which ND filter should you use? ND filters come in different shapes (many companies make round filters that screw into the front of the lens. If you have multiple lenses with different sized filter threads, you would need to buy a set of ND filters for each lens—an expensive proposition. That’s why many photographers prefer square or rectangular filters that slide into a filter holder, which attaches to an interchangeable adaptor ring that screws onto a lens. Change lenses? Simply change the adaptor ring. This way, you only need one set of ND filters. Lee Filters, a UK-based company, makes its filters through a complex hand-made process, and the results are preferred by many serious photographers. Adorama carries a complete line of Lee Filters.
The other thing to know about ND filters is how dark they are. The darkness of an ND filter increases exposure by a fixed amount. How this amount is expressed differs depending on the filter manufacturer. But photographers who are just starting out may be thrown by Lee’s number designation, and how it relates to exposure value. How does “0.3 ND” relate to aperture values? Let’s see.
If you need more than 3 stops of filtration you can combine two or more ND filters. You can also combine ND with other filters, such as grad ND or grad color filters. If you stack filters, consider investing in the ProGlass ND filter line to avoid problems that can occur in the infrared and UV ends of the color spectrum when shooting digitally.
Soft grad filters, before (top) and after (above).
ND Grad Filters
A variation of ND filters is the ND Grad filter. For this, a square or rectangular filter in a holder, such as the Lee lineup, wins hands-down when compared to a circular screw-in filter. ND filters are used to reduce the dynamic range between bright skies and landscapes, which are somewhat darker. When exposing for a landscape, a photographer may have to compromise between a properly exposed ground and the sky. If the ground is properly exposed, the sky may be blown out with overexposure. While HDR (combining multiple images shot at different exposures) is one way to resolve this, the way to do it in camera with no post-processing is to use a graduated Neutral Density filter.
As with solid ND filters, ND Grads come in a variety of densities/intensities. They also come in “hard” and “soft” variations: A Hard ND Grad has an abrupt transition from grey to clear, creating a harder line in the image. This is good when shooting a seascape, for instance, where there is a solid, unbroken horizon. A Soft ND Grad has a more gradual transition, and is better for horizons that are not as even. Right: Soft (right) and hard (left) ND filters, both rated 0.6 by Lee, side by side.
ND Grad filters can be placed with horizontal, diagonal, or even vertical transitions, depending on the scene and the transition area can be shifted up or down within the holder, depending on the location of the horizon.
For more information and to purchase ND and ND Grad filters, go to the Adorama Lee Filters department.
