The Heliopan 27mm Solid Neutral Density 2.0 Filter is an ND filter with a 97x filter factor that provides a 6.6-stop exposure reduction. Its 2.0 density creates a darkening of the entire image, allowing you to photograph with a wider aperture or slower shutter speed than normally required. By slowing your exposure time or increasing your aperture, you are able to control depth of field and convey movement more easily. Neutral density filters do not affect the coloration of the image and are ideal for pairing with other filters. To prevent internal ghosting and reflections, each glass surface includes four layers of anti-reflection coating. Together, these eight coatings offer greater protection to the filter substrate and help it to stay clean for longer than with uncoated filters. This Heliopan neutral density filter is constructed from Schott glass for increased optical clarity as well as color fidelity and features a brass filter ring for enhanced durability and jamming prevention.