This female photographer (Ursula) is hand holding a Sigma 50-500 at 500mm. Impressive.
Notice how good Farley, her Old English Sheepdog, is. He waits and he waits very patiently, while she takes photos of the snowy owls that have migrated from the arctic to our area.
Old English Sheepdog
Camera: Canon 7D ISO 400 and 1/320
Lens: Sigma 120-400 @273mm and f/9
Processed with Darktable 2.0.4: http://www.darktable.org/