- set your focus-mode to
AF-C. This is 'continuous' autofocus which means that while the
shutter-button is half-pressed the camera will continue to attempt to re-focus when the subject is moving. Set your AF-area mode to
Single-point AF or
Dynamic-area AF and use the centre focus point in the viewfinder (at least initially till you start getting sharper results). Follow your dog in the viewfinder with the
shutter-button half pressed - you should see the dog come into focus. Then press the
shutter-button the full way to take the shot when desired.
Cheers.