Sapphire’s RackDefocus filter generates a defocused version of the source clip using a ‘circle of confusion’ convolution. This effect is often preferable to a gaussian blur for simulating a real defocused camera lens, because bright spots can be defocused into clean shapes instead of being smoothed away. The iris shape can be controlled using Points, Pointiness and Rotate, and the Use Gamma parameter can adjust the relative brightness of the blurred highlights.