Full gray NDx16 filter Cokin P. The full ND NDx16 filter is designed to reduce the amount of light entering the lens (by 4 stops). Gray filters, by reducing the amount of light, increase exposure time and allow for greater depth of field. They can be used for both black and white and color photography. The NDx16 filter has a light transmission of 6.25%, preventing overexposure of bright areas in the image. Using gray filters allows you to use longer exposure times and capture more details in the photograph. It is an essential element for a photographer when taking landscape photos. The filter is uniformly colored and allows for mounting on the base, where up to three square filters or one round filter can be attached.