Focal-Length
改變focal length(焦距長度)除了讓拍攝目標拉近放遠之外，也改變了三個視覺要素
1:field of view(視野)
2:depth of field(景深)(焦點前後清晰範圍)
3:perspective(透視)
Dolly Zoom
The Dolly Zoom: More Than A Cheap Trick
https://www.youtube.com/watch?v=u5JBlwlnJX0
Dolly Zoom Vertigo Effect with Moza Air 2 and Mini S Gimbal
https://www.youtube.com/watch?v=e-gZUagXeOE
Mastering the Art of The Dolly Zoom
https://www.youtube.com/watch?v=Amj6RiGiTOE
