I fitted the 100-300 and teleconverter, set it to 300mm, set the shake reduction for 600mm. Aperture was set to f/16 and ISO to 400. For a notion of how much magnification this achieves, the image above is the scene from the same vantage point using a 35mm lens.

All were shot at the same f/stop, exposure times varied from 1/13 to 1/6 second.