The Rodenstock 67mm Digital Vario ND MC Slim Filter is a solid variable neutral density filter providing a controlled reduction of about 1.5 to 5 stops. The 0.45 to 1.5 (2.8x-32x) 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, allowing you to previsualize the additional exposure length required. By slowing your exposure time or increasing your aperture, 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 each represent one stop of neutral density. While the filter will cleanly produce up to 5 stops of neutral density, up to 9 stops of neutral density can be achieved by rotating the filter past the setting scale. However, when working with densities greater than 1.5, color neutrality becomes gradually compromised with increased blue-violet coloring to imagery. Rodenstock's Digital MC filters feature a hardened, black anodized aluminum slimline filter mount with front filter threads. This allows the attachment of other filters or lens hoods while still maintaining the vignette-reduction capabilities of a slim filter. It is constructed from multi-layer coated hardened optical glass.