Graduated Neutral Density Filters
Graduated neutral density filters allow you to shoot high-quality images in scenes where brightness varies. A typical example is a photograph of a seaside scene with a bright blue sky. If you expose for the foreground, the sky may be too light, and if you expose for the sky, the background is too dark. Using a graduated filter, you can correctly expose both the foreground and background without needing to use photo software to correct your exposure.
What Are Neutral Density Filters?
A neutral density filter is a glass or plastic filter placed in front of the camera lens to reduce the amount of light reaching the camera sensor. Neutral density filters vary in strength from less than half a stop to as many as 24 stops. A rectangular ND filter fits into a holder mounted in the front of the camera, while circular ND lens filters screw onto the front of the lens. ND filters don't affect colors.
Solid ND filters reduce the light reaching the camera sensor by a fixed amount, while variable ND filters use two layers of polarized glass to adjust from nil to ten stops or more, depending on the type of filter.
Design of Graduated Filters
As the name suggests, graduated ND filters vary in density from top to bottom, allowing you to take a photo of a dark foreground against a bright background while achieving correct overall exposure. The strength of a graduated filter varies from nil at the top through to three, four, or more stops at the bottom. Graduated filters have a soft or hard transition between light and dark regions.
A reverse graduated ND filter differs in that the darkest portion of the filter is in a band through the center of the filter. Use these filters to take photos of sunrise and sunset when the sun is just above the horizon. The top section is typically one stop darker at the top, approximately three stops darker in the middle, and clear at the bottom.
ND Filters and Motion Blur
Solid neutral density filters let you control the amount of light so you can use a slower shutter speed or wider aperture setting. A slow shutter speed helps create motion blur. This can create an impression of movement in clouds, or smooth the appearance of flowing or moving water. A wide aperture allows you to control the depth of field by throwing the background out of focus in brightly lit conditions.
Graduated, neutral density, and color effect filters allow you to control exposure in cameras to achieve better photos. Check the full range of graduated ND filters at B&H Photo and Video to find the right filter for your next shoot.