From a clear centre, the Cokin Radial Zoom fiter duffuses colours & light in the form of rays towards the picture edges, like a fireworks display. By night, it's the filter to use for neon signs, illuminated monuments, general views of the lights of the city, & the brilliantly lit avenues. By day, highly-colored subjects & backgrounds irradiate their colors with the same intensity. Recommended for focal lengths of 35-50mm & apertures of f 5.6/f 8.