"The basic idea of the Bokeh Kit is put a cutout shape in front of the camera lens, which shapes out-of-focus lights using the shape on the cutout [Optics nerd time: I'm not sure of the exact optics going on here, but what I'm guessing is that it masks the circle of confusion formed at the image plane with the cutout shape. Someone please correct me here if I'm wrong]. Udi took the idea of his DIY shaped bokeh and turned it into a product where you can swap in one of a number of pre-made cutouts. The shaped bokeh is sharp - in particular, I do like how it turns otherwise plain-old background bokeh into sharp shapes, which (when the composition works) match a sharp foreground subject."
