P.173 Using the ND Filter (Tip #004)

The Neutral Density (ND) filter allows you to shoot photographs at lower shutter speeds by reducing the amount of light that hits the camera sensor. The term neutral density refers to the blocking out of light without producing a colour cast on the final image. Your camera has an inbuilt neutral density filter which reduces light intensity to 1/8 of actual levels (sometimes referred to as ND8, or equivalent to 3 stops).

The ND filter can be used to create images with silky smooth water or clouds. Because exposure times are increased through having applied the filter, it is usually necessary to use a tripod when taking this type of photo.

This photo I took using a tripod. The shutter speed of this shot is 1/8th second. Because this photo was taken during autumn in dark woodland I was able to take this photo without the use of an ND filter on my camera.

Here you see a situation in which I was attempting to blur the background by having you cycle past me as I took the photograph. The effect that I wanted has been achieved to a partial extent, but would have been much better if I could have applied an ND filter (which I don't have on my camera). The reason the background is not very blurred is that the shutter speed is 1/100th second, since any attempt to use a longer exposure would have resulted in an over exposed shot without the aid of an ND filter.

One other thing to bear in mind when taking this type of shot is the fact that you want to use the lowest possible ISO setting, since you don't want to offset the effect of the ND filter through having an increased ISO setting. Lock your camera to ISO 80 (the lowest setting on your camera) before taking this type of photograph (see my tip #001, to be found under 'Tags' on the right).

The photograph right is another example of this technique being used on a waterfall. The technique can also be used to good effect on waves and, if there is a reasonable amount of movement in the clouds, on skies .







For further reading, see: 8 Tips for Long Exposure Photography on the Digital Photography School web site.