The 58mm ND Fader Filter from Genus is unique in the world of neutral density filters. Other companies make you buy individual ND filters to meet your needs (i.e. 1-stop, 2-stop, etc.). Genus provides one filter that generates 2-8 stops of neutral density depending on how it is rotated.
In addition, the filter is indexed so you know exactly how many stops of neutral density you are getting. It screws on like any other filter and with a mere twist of the convenient rotating handle on the filter ring, you dial in your filtration. No need to constantly change filters - as the light changes, just dial in another grade of filtration.
Neutral Density filters have several uses and offer the possibility to achieve otherwise unachievable results. They enable the shooter to adjust exposure without affecting color balance. ND filters appear gray and reduce the amount of light reaching the film.