The 62mm Haida NanoPro Variable Neutral Density 1.2 to 2.7 Filter is a variable neutral density filter that provides an exposure reduction of 4 to 9 stops. The 1.2 to 2.7 density creates a darkening of the entire image, allowing you to photograph with a wider aperture or slower shutter speed than normally required. The degree of density is easily controlled by rotating the front filter ring, helping you to predetermine the additional exposure length required. By increasing your aperture or slowing your exposure time, you are able to control depth of field and convey movement more easily. For easier, repeatable control over density settings, the front ring is also visually demarcated with dots that represent different density values and includes a rotation lever to further enable fast, as well as precise positioning of the front ring.