He takes unfiltered photos mostly and then 1 or 2 through the filter, and blends in the soft images in PS so he can control the level of fuzziness. I really like the effect. It brings out the constellation shapes and star colours, and looks very atmospheric.
Yes.. high quality lens (sharp), and then soft filter... to unsharp the image.
In my days we were using white gause over the lens to achieve that esoteric feeling on portraits.. David Hamilton was famous for this technique back in late '70-ies.
