If you try to get the black color right, the white looks deathly pale. "There's a similar problem with respect to depth of field." A photo always has a single focal point, "explains Yang." If you focus on a bird's beak, the feathers are going to be out of focus.
至於景深也有同樣問題，「一張照片總有一個聚焦點，聚焦在鳥嘴，羽毛就會鬆掉；聚焦在前爪，後爪就會模糊。