I want to use my FS5 to shoot the bride over the shoulder of the groom and have the groom's shoulder to have soft focus. I realize that this could depend on the distance, but I would think I might be up to 20 feet away. What lens and f stop would like give me this result? At the moment, I only have the kit lens 18-105mm f4, so I am assuming I won't get much bokeh under these circumstances.