Gray filters, also known as ND filters (Neutral Density), reduce the entire visible light spectrum evenly across the entire filter. This does not affect colors and contrasts. This reduction is useful in various applications. For example, an extended exposure time can create flowing effects in moving water or be used in bright environments with a wide aperture and extended shutter speed. The gray filter used here has a filter factor of 4, which extends the exposure time or aperture increase by 2 stops. The ND filter features excellent optical properties. The high-quality lenses are embedded in a precisely crafted metal frame. The filter also has an additional front thread, allowing for combinations. It is transported in a protective case.