I was testing using the 2X converter on the 70-200 lens as still searching for a good 'travel' set-up for bird photography. It was bright and sunny in the morning and the results were pretty good. When it clouded over, focus was not so accurate. Lots of Black-tailed Godwits feeding and then roosting on the mud banks. I always enjoy the way the light and dark change as the flocks wheel around. Coot, Moorhen and Widgeon all obliged to test the lens combination.