Hoya Misty-Spots are available in four types: Gradual, Breeze, Windmill, and Halo. They have a sharp central image with a pleasant blurring of the outer field.
Four Types of Misty Spot Filters
With Misty-spot Gradual, blurring appears to emanate from the center
With Misty-spot Breeze, there is a uni-directional streaky blurring of the background
With Misty-spot Windmill, blurring appears to swirl around the center
With Misty-spot Halo, blur appears to radiate from a single point at the edge of the field.