You could do this with your 70-200, Rich. I used a Nikon tube, but the Kenko set for $100 is more bang for the buck. I just set up about 5 feet from a popular perch and waited. This was taken in bright sun with a very light cloud layer, lens set at 200mm, no filter other than UV, ISO 800, 1/30 @ f16 (those tubes eat a lot of light). The extension tubes are a little vexing because they play h*ll with your AF and limit the distance you can be from the subject.