Why is it when I turn the camera on, my screen keeps moving up and down?

[AC Question]

why is it when i turn the camera on, my screen keeps moving up and down

Hi guys, I'm new to samsung, i just bought an s6 a month ago. Im very careful with phones in general, i dont know how this issue started... everytiime i go on camera, the screen keeps moving up and down non stop when it focuses on something. The picture comes out normal though...for now... lol