Those of you who follow my Flickr stream will have noticed the abundance of photos displaying creamy, silky water surfaces - the result of a heavily darkened ND filter.

ND filters (short for Neutral Density) are quite simple: pieces of grey glass, depriving the lens of light, thus forcing the camera to use longer shutter speeds. One would wonder, why anyone would want less light, when we pay large amounts of money for lenses with wide aperture and lots of light? There can be many instances when the use of an ND filter is justified. For example, in very bright sunlight, when I want to be able to shoot with a wide aperture for bokeh. Or, in my case, when photographing water and wanting that silky look that comes from water splashing about during a very, very long exposure.

A common ND filter is the ND8. This is a 3 stop filter, which means that you have to open your aperture 3 stops to get the same amount of light as without the filter. I own an NDx1000 filter (10 stops). This filter increases the shutter speed by times one thousand. So if my normal shutter speed would be 1/10, I end up with 100 seconds. 0,5 seconds turn into 500 seconds. And here’s what happens during that time.

Created with Admarket’s flickrSLiDR.

The NDx1000 requires a bit of special handling. When you look at it, you see - blackness. It is almost solid black, so when attached to the lens, you’ll see nothing in the viewfinder. Nothing at all. So composing the image and focusing must be done beforehand, and the filter is screwed into place just before taking the photo. This doesn’t allow forvery spontaneous photos, but it certainly holds an element of surprise - what you see on the LCD is often much more surreal than you’d ever expected. The way the motion of water and clouds blur in a single frame  is quite special and it’s always a thrill to see the result after those minutes in the dark.
If you need more exposure time than you camera allows (usually 30 seconds) and use the B mode, a remote control is necessary, as holding the shutter button down fith your finger will result in motion blur. It is essential to keep the camera steady, so in addition to the remote, you’ll also need a sturdy tripod for those dreamy shots.

Post processing involves getting rid of the hotpixels (red or white pixels scattered across the darker areas as a result of sensor warming due to the long shutter speed) and perhaps also some noise filtering. The NDx1000 tends to give a rather warm color tint to the photo. I usually don’t correct this in the RAW converter, as I feel it adds to the dreamy wuality, but this can of course be adjusted.

A dark ND filter like this is quite a pricey item, but I feel it was worth the investment as I really enjoy to see the clouds sail by and the water turn silky in my new landscape photos. If you don’t want to invest big bucks in and NDx1000, go for an ND8 to begin with. It will give you the same results, only you have to be onsite at a later hour for a darker window of time.