I have been a fan of Lee and Hi-tech neutral density filters and use them during workshops, but now there is a new name in the game. Breath though Photography offers a great line of filters so please check the link. Soon enough I will have some of their filters in hand and will be able to show people how they work.
In Hawaii, the sun is bright and harsh. Graduated Neutral Density filters allows an image make to control the light and manage the quantity of light coming in. This intern allows individual creativity to flow and for motion to be used as a compositional element to evoke emotion.