On our visit to Bombay Hook National Wildlife Refuge we saw large flocks of American Avocets. The only problem was they were so far out in the Shearness Pool. Photographing large flocks was acceptable at 600mm, but I added a 2x teleconverter to get to 1200mm for individual Avocets. Even then I had to crop quite tightly for the individual Avocets. These are also handheld, so I upped my ISO to 1200 ISO and f/16 hoping for more sharpness with the 2X Teleconverter.