I was tracking 3 or 4 Goldcrests foraging in the undergrowth and trying to predict when and where one would surface. When one suddenly popped up just in front of me I didn't panic for once but managed to fire off a quick burst. The autofocus worked well; most of the pictures in the sequence were sharp, at least on the head. The picture is cropped but only to make a more interesting composition, not to zoom in on the bird. This experience increased my confidence no end and since then I've managed to get sharp close-ups on 2 more occasions.
There are 3 more sharp images in the sequence and I'm afraid I can't resist the temtation to post them all so I hope you will indulge me. :-)