STOPPING POWER

Mike Harris demonstrates the light-blocking capabilities of different strengths of ND filter by blurring a waterfall

- Mike Harris

15 MINS

Photographers often try to get as much light into their camera as they can, investing in bodies that boast topnotch image quality at high ISOs and fast lenses that gather as much light as possible via super-wide apertures.

However, there are times when we want to reduce the amount of light that enters the camera, so that we can produce longer exposures. This might be to blur moving clouds, smooth out choppy waters, or exaggerate intentional camera movement. You can increase exposures by using a lower ISO and/or narrower aperture, but very often even a camera's base ISO and the very narrowest aperture aren't enough to capture sufficient motion (not to mention the latter can reduce image quality). The solution in these instances is to use a neutral-density filter.

ND filters act a little bit like sunglasses for cameras. These tinted sheets of glass block light to allow for longer exposures, and they come in various strengths, so you can tailor the light-blocking properties according to the lighting conditions you're shooting in, and the aesthetic you're trying to achieve. We paired our NiSi V7 filter holder with the most common strengths of ND filters - 3-stop, 6-stop and 10-stop to demonstrate how each affects the same subject.

Remember that the speed of the subject and available ambient light will affect the outcome too, so have fun experimenting. You can even stack ND filters to increase the strength - so a 3-stop and 6-stop filter would together block nine stops of light, for example.