Can I Use ND8 Filter in Long Exposure Photography?

Oftentimes, we use ND filters in landscape photography to achieve a slower shutter speed for capturing the flow of water, clouds.

How slow we need is depending on how fast the movement is and how much blur we want to bring for our image.

If you’re shooting around dusk, at say f/8 and ISO 100 you’ll likely to end up with a shutter speed of say 1/10th to 1/20th.

ND8 filter(3 stops ) will double that 3 times (on stop more is twice as much light: twice the exposure time, or double the aperture area or double the ISO of the sensor). We can represent this as 2^3 or 2 x 2 x2 = 8 times the exposure. This would give us shutter speeds ranging from 0.4 seconds to 0.8 seconds. This will be long enough for some jobs - fast-moving water maybe. But for cloud streaks, or to get that foggy effect of waves continually crashing onto rocks or getting a completely flat seascape you’ll need 30 seconds, 2 minutes or maybe longer.

                   Without nd8 filter                                                       With nd8 filter

Of course, you can also adjust this by stopping down the aperture. Set the aperture from f/8 to f/11 will double the times again, and then to f/16 and so on.

In strong daylight with shutter speeds up in the 1/250th to 1/1000th and above, a 3 stop is not going to make an appreciable difference in the landscape: 1/250th becomes 1/30th and 1/1000th becomes 1/125th. Not long enough to provide an appreciable effect on water, or clouds other than to blur them slightly.

The intentional blurring of motion should be obvious - if it’s just a bit soft, it looks like you just took a fail picture.

An ND64 6 stop filter (2^6) or 64 times the shutter speed is more useful here: 1/250th becomes 4 seconds for example.

And of course, you can also buy an ND1000-10 stop (2^10) or 1024 times more shutter time - and even 1/1000th of a second can become just over 1 second.

So, yes if the light is already pretty low, 3 stops more shutter time could be the answer, however, I would buy a 3 stop and a 6 stop. If you need more, you can double them up.

Get square filters and a holder system like the K&F Concept makes. This way you can just slide the filter up and down when you need to see through the finder. It makes it easier to double up on the filters if you need to as well.