I recently tried using Neutral Density (ND) Adjustable Variable Filter for long exposure photography at night.
A ND filter is very handy for long exposure photography. A ND filter does not affect the colour of your photo and blocks out light and allow less light into the camera sensor. This means you can use your camera at incredibly slower shutter speeds thereby extending the exposure. If you are using a variable ND filter, you can adjust the degree of darkness. Of course, the basic requirement for use a ND filter is a sturdy tripod or a flat surface to avoid camera shake.
ND filters can be used for achieving great effects in photography. They can not only be used for getting motion blur effect on a waterfall or clouds and even can be used to make moving people disappear in a crowded tourist place.
Each ‘stop’ of a ND filter reduces the amount of light entering the camera by a factor of 2, i.e.:
1 stop = ND2 = 50% transmittance
2 stops = ND4 = 25% transmittable
3 stops = ND8 = 12.50% transmittance
4 stops = ND16 = 6.25% transmittance
5 stops = ND32 = 3.12% transmittance
I would love to hear your experience of using ND filter.