If you use heavy 500mm or 600mm lenses, a good tripod system a tripod and a tripod head is a must, simply because hand-holding these lenses is not practical. Canon 300mm lens, Canon 7D Just a few birds I’ve taken in the past. I have noticed that birds, especially hummingbirds and Finches, can see the focusing laser when it activates. Cormorant in flight, Canon 7D, Canon EC 200mm 2.8L II RSM, 19 points A, ISO 100, 1/1000s, f/5.6, Spain. 3. Light is critical. I can't emphasise this enough. To get a feeling of the bird’s world, then you need to get down to their level! Canon EC 200-400mm f/4 L IS RSM is announced and have built in 1.4x teleconverter, that can turn it in a 280-560mm f/5.6 lens instantly, but I don't know when this lens will be available yet.