Have you ever had the problem that you were too close? I was using my 500mm lens with a 1.7 converter and the meadowlark was too close. I didn't have room to back up on this shot. Eventually, I was able to back up, but he was in the tree more and his tail still didn't show. I've been shooting birds which come to my yard. I live in a rural area in a housing tract. I have two acres with one acre I left natural along a creek. I get quite a good variety of birds.