TAKE IT TO THE MAX
If you want to maximise motion, use an extreme ND filter
once you start experimenting with capturing motion, don’t be surprised if a) you get hooked on the technique and b) you want to take the effect much further. to do that, you’ll need to arm yourself with an ‘extreme’ neutral density filter. A ten-stop nD is the most popular and probably the most versatile for general use, though weaker six-stop and stronger 15-stop nDs are also available from manufacturers such as lee Filters and hitech. With a ten-stop nD filter exposures are increased by 1,000x, so you can leave your shutter open for several minutes in broad daylight and literally capture the passing of time. Drifting clouds record as delicate streaks, moving water turns to milk and the effect can look stunning.