• Use a neutral density filter to reduce light.photo filters and lens hood image by FrankU from Fotolia.com
  
  Using a neutral density (ND) filter gives photographers a wide range of creative control by reducing the amount of light into the camera. ND filters are a staple in many professional photographers' equipment bags, but their uses are sometimes lost on amateur or new photographers who don't understand or appreciate their application. ND filters are usually gray in color and are available as full effect or graduated effect, in which half the filter is dark, the other is clear.
  
  

Filter Strength

• Full-effect ND filters come in different strengths and can be used individually or combined for greater reduction. An ND2 filter reduces the amount of light entering the camera by one full stop. If you are shooting at 1/250th of second, this is reduced to 1/125th. An ND8 filter reduces the light by three full stops. Again, if you start at 1/250th shutter speed, attaching the filter allows you to shoot at 1/30th of a second. ND filters increase in strength up to ND1000000, where the amount of light is reduced by 20 full stops. When using ND filters, always use a tripod for the camera. As shutter speed reduces the possibility of camera shake increases.
  
  ND filters also come in a graduated effect, in which half of the filter is dark. These filters are great when you need to balance exposure between a bright or hazy sky and the landscape. They also come in different strengths and colors.
  
  

Tips for Use

• If you are trying to achieve a cascade effect of water over a waterfall, use an ND filter to reduce the shutter speed until the water starts to blur. Start with the normal exposure, then experiment with different grades of filters until you have reduced the shutter speed to create the desired effect. Another application for full-effect ND filters is to reduce the depth of field of a scene by shooting at a wider aperture. Meter the scene normally, then test with different grades of filters until you have achieved the effect. Use a tripod to minimize camera shake and to maintain the same shooting position.
  
  

Use With Point-and-Shoot Cameras

• While ND filters and systems are traditionally designed for either film or digital single lens reflex cameras (SLRs), they can be used with point-and-shoot cameras. Because the filter is too large to attach to the front of a point-and-shoot lens, simply hold the filter in front of the lens. Hold it as close as possible without touching the lens, to prevent light from reflecting off the rear of the filter into the camera. You can also do this with SLRs. It saves time when experimenting with different strengths before taking your final picture.