9.5 | ND FILTERS
As you know
by now, a slower shutter speed makes for a smoother image, but it also makes
for more light on the sensor. One way to correct the amount of light is to
adjust the aperture. However, this in turn affects the depth of field of the
image. To still get the right light, you can use ND filters (ND=Neutral
Density). The ND filter acts as a kind of umbrella or sunglasses for your lens.
This is because the filter blocks some of the light to avoid overexposing the
images.