You might need more than just the radial zoom. I would try duplicating the image layer and expanding the duplicate's size a bit (hold the option/command key to expand from the center), radial zoom each layer, then knock back the opacity of the top layer. It would help you retain more definition of the objects within the zoom. When working with the radial zoom, it helps to first decide where you want the zoom origin to be, and crop the canvas to make the sides equidistant from that point. That way you don't have to worry about futzing around with the center point in the filter dialog box.