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Neutral Density Filters
Neutral Density Filters are gray filters which are designed to evenly block out a percentage of all visible light.
Since adding a Neutral Density filter reduces the amount of light we will need to adjust the Shutter Speed and/or Aperture.
One reason to use a Neutral Density Filter is to increase the aperture opening of your lens. This is done to achieve a shallower depth of field, separating your subject from your background. Keeping your subject in sharp focus while blurring the background.
Slow Shutter Speed
More commonly though a Neutral Density Filter is to slow the shutter speed to capture a motion blur.
Since there is less light entering the lens, you can reduce the shutter speed without needing to change the aperture. Using a Neutral Density Filter can let you shoot at a very slow shutter speed even if it is bright out.
When taking a photograph of a waterfall it is common for a photographer to use a neutral density filter to slow down the shutter speed. That way instead of freezing the action of the waves and seeing individual water drops, the water is softer and more flowing.
Neutral Density Ratings
There are three levels of Neutral Density Filters which block out different percentages of light.
ND 2 or ND 0.3 - Blocks 1 f-stop
ND 4 or ND 0.6 - Blocks 2 f-stops
ND 8 or ND 0.9 - Blocks 3 f-stops
Buy a Neutral Density Filter Set
Combining ND Filters
Neutral density filters can be combined together for a greater effect. For example you can combine an ND 2 and ND 8 to create a ND 10 that blocks 4 f-stops.
If you are looking to combine ND filters you should use a drop style filter like the ones by Lee or Cokin. Stacking traditional circular filters will result in vignetting around the edges of your photos, especially on wide angle lenses.
More on Neutral Density Filters
- Variable Neutral Density Filter
Variable ND Filters are one of my favorite new photography tools. This one filter replaces an entire set of ND Filters.
- Split Neutral Density Filters - ND Graduated Filters...
A Split Neutral Density Filter or Graduated Neutral Density Filters block out different amouns of light one side of the filter than the other. These filters let you better control the exposure of an overal...