The Cokin Clearsky Filter blocks specific wavelengths of city lights, such as those from sodium and mercury vapor lamps. This removes the yellow and orange glow of streetlights for nighttime city photography. Additionally, it enhances the contrast of the sky for astrophotography by darkening the color gradient of the sky background and highlighting stars or the Milky Way. Features: - Double-sided multi-AR coating and AF coating (waterproof, oil-resistant, and scratch-resistant) - High-resolution phosphor laser neodymium glass - Recommended operating temperatures: -10°C to +40°C - Diameter: 52 mm.