The Cokin Radial Zoom #185 filter features numerous rings etched concentrically around a clear, one centimeter center spot. This causes bright highlights originating in the center point to be stretched out to the edges. This effect is comparable to shots taken with a zoom lens when the lens is "zoomed" during the exposure. This attachment should not be used for subjects dominated by a light sky or which feature empty expanses of snow or water in the background, as it is the unfocused areas of a lively, colorful background which emphasize the zoom effect.
This filter measures 85 x 85mm and fits the Cokin P series holder.