The NiSi 40.5mm True Color ND-VARIO Pro Nano 1-5stops Variable ND is designed to mount onto lenses with 40.5mm front filter threads and provides an exposure reduction of 1 to 5 stops. The 0.3 to 1.5 density creates a darkening of the entire image, allowing wider apertures or slower shutter speeds than usually possible. The degree of density is easily controlled by rotating the front filter ring with or without the included silver lever, helping you predetermine the additional exposure length required. By slowing your exposure time or increasing your aperture, you can control the depth of field and convey movement more easily. The transition of density occurs smoothly which allows the photographer or videographer to adjust exposure length to the exact amount required for a given scene. For easier, repeatable control over density settings, the front ring is visually marked with numbers representing the different stop values. The ring features silver side knurlings for a secure grip and easy installation and removal. For those using this filter with cinema or video cameras, combined adjustments of aperture and this filter allow fine adjustments of the depth of field while retaining the designated frame rate.The Variable ND offers True Color that avoids color shift seen in other Variable filters. The NiSi True Color ND-VARIO Pro Nano 1-5stops Variable ND is made from high-definition optical glass for the best resolution and quality. The glass is coated using the NiSi Nano coating providing a waterproof, oil-proof and anti-reflective coating to avoid ghosting and reflections.