Core Skills: Moving Image (Racking)

Racking Shot is when the focus in a shot focuses on one object then changes and focuses on another.
This video from youtube is a tutorial about pulling focus and rack focusing.
https://www.youtube.com/watch?v=b5KXQw48SNk

These are a few images

Non-focus in the foreground of the sunflower. While the Middle ground and background are in focus.

Then it changes from the top image. where the sunflower in the foreground is in focus and the middle ground and background are not in focus.