ND standards can be classed as essential in modern photography. These filters absorb light evenly across the visible spectrum, therefore reducing the light entering the lens without affecting the image colour. Traditionally used on film for extending shutter speeds in bright conditions, they are now becoming essential to digital photographers for reducing the sensitivity of sensor chips on cameras which have relatively high minimum ISO settings.
ND Standards extend exposure times allowing for movement in an image, be it people, water, foliage or clouds. If used with care the effects can be impressive.
Blenders feature an effect transition that occurs over the entire length of the filter, starting at the top and graduating all the way to the bottom. This allows for a graduated effect across your image without any specific horizon line.