Camera Controls and Settings: Neutral Density Filters
Understanding what a neutral density filter does, and how it can expand your aperture options is an important concept for every shooter. Learn to get more control over your depth-of-field by using this effective tool.
The exposure triangle deals with the camera controls you can use to control exposure, but each camera control has side effects you may want to avoid. One effective way to help control your exposure without introducing unwanted side effects is using Neutral Density Filters. Essentially a neutral density filter is like putting sunglasses on your camera. It reduces the intensity of the light that hits your sensor with no negative side effects. This can allow you to reduce your exposure if you’re on your highest f-stop and your shot is still overexposed, or allow you to shoot at a lower f-stop to control depth of field. They can also prevent the temptation to use a faster shutter speed to reduce your exposure. These filters can be built in to a camcorder, screwed on directly to the front of a lens, or placed in a matte box. They can be a fixed density, or have a variable control for ease of use. There are various different ways that that ND filters are measured, for example, a filter labeled .3 ND2 or ½ will all reduce light by 1 stop. Built in ND filters are typically found on professional level camcorders. Most will have 3 different options ranging from 1 to 6 stops of light reduction A screw on ND filter is attached to a lens using the inner screw threads on a lens. Most camera models print the filter diameter on the lens right where the lens cap attaches. It's usually indicated by a circle with a slash through it followed by the size in mm. If you have a matte box on your camera, you can purchase ND filters to slide inside of it. Neutral Density filters are an accessory or feature that no shooter should be without. They help you gain true control over your exposure with no undesirable side effects.