Water in blur motion with an ND filter

The remnants of old pier pilings dot the water all along the Hudson and East rivers in Manhattan. I have been wanting to do some photos of them where the water is a milky blur in contrast with the craggy sharpness of the wooden pilings. This past weekend I had the opportunity because the weather was overcast enough to lower the exposure time necessary to cause the blur. Even so, I needed an even lower shutter speed to achieve the effect I was after. For this I relied on a neutral density filter that would knock 9 full f-stops off the exposure. At an ISO of 100 that gave me 30 seconds at f/8 to f/11, enough time and depth of field for the motion of the water to blur while the pilings remained sharp.

One of the final images, taken with a Nikon D800 at f/9 and ISO of 100. I used a 9-stop ND filter to increase the exposure time, but probably could have achieved the same effect with a 6-stop filter instead. One problem with the 9-stop filter is that it is so dark you cannot even see the subject through the viewfinder when the filter is on the lens. I had to remove the filter and refocus for every change of scene.

This is the actual scene shown how it would have been without the ND filter. Even stopped down to f/16 I was only able to slow the shutter speed to 1/4 second for this version. 

This is the scene shot at 15 seconds. I wanted the water to be milkier than this so I increased the speed to 30 seconds for the final versions.