Sometimes there is just too much light.
You see a nice scene, a waterfall, a fountain or great moving clouds. You would like to blur all the movement and so you put your ISO to 100, your aperture to f16 and still you’re not able to achieve a long enough shutter speed.
What to do? Use a Neutral Density filter, also known as an ND filter. An ND filter is basically a grey piece of glass. Like sunglasses, it takes away light and therefore you can dial in a longer shutter speed. They can be bought in different strengths. The higher the number the stronger the effect. What is very important is that the grey really is grey. It should be absolutely neutral in color to avoid strange color casts. Therefore don’t buy the cheapest. Also the variable ND filters, which look very convenient, are hardly ever neutral over the entire range.
Apart from achieving a long shutter speed the ND filer can also be used to minimize depth of field. When there is too much light to be able to open up your aperture wide enough to minimize your depth of field, despite your ISO and shutter speed being already at their minimum and maximum settings respectively.
3.2s, F16, ISO 100, ND8 filter
N.B. If some of the terms in the above article are unfamiliar to you, then you might like to consider joining our Beginner’s Photography Course.