I have photographed Rainbow Falls in Whiteshell Provincial Park for decades. While I had noticed some swirling of the waters beneath the falls, I was not aware of just how much there was. Of course, the amount of swirling changes depending on how much water flows at any one time. I decided to make the effect more pronounced by using a Singh-Ray Variable Neutral Density Filter with built-in polariser in front of the lens. This reduced the amount of light reaching the sensor considerably, permitting me to select a longer exposure (3 seconds in this case) to allow the motion of the swirling water to show up distinctly. This type of motion could not be achived otherwise in broad daylight. Motion that existed but was not apparent before is now revealed. This particular filter reduces the incoming light by up to 8 stops.