The Hoya 77mm Solas Variable NDX 0.4 to 2.6 Filter is a solid variable neutral density filter that provides an exposure reduction of 1.3 to 8.7 stops. The 0.4 to 2.6 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 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 lines that represent different density values.
This Hoya variable neutral density filter is constructed from optical glass for clarity and color fidelity. To prevent internal ghosting and reflections, each glass surface includes 10 layers of anti-reflection coating. These coatings also provide further protection to the filter substrate and helps it to stay clean for longer than with uncoated filters. The design of this filter has also been optimized for use with digital sensors and to promote nearly flat attenuation of visible light and infrared light. Due to imaging sensors' greater susceptibility to infrared light, compared to traditional film, color casts can occur when photographing darker subjects that require increased exposure times.