Can anyone tell me how to focus on the two swans, I focused on the right hand swan
kept the shutter button half way and re-composed but the left hand swan is a lot softer
than the right, is this the right way to go about it?
I’d imagine it’s simply that you’re not getting much room for error at f/6.3. Seeing as you took this at 1/500 sec, you might have considered closing the aperture a stop or two and shooting at 1/250 or 1/125 sec.
Alternatively (if you were not using a tripod, say) you could put your ISO to 800 and shoot at 1/250 f/11. At f/11 you should get enough DoF to cover this shot.
Now you just have to go back and find the swans again!