景深预览按钮
/ˈdɛpθɒvfˈiːld ˈpɹiːvjuː ˈbʌtən/
n
English: depth-of-field preview button · 景深预览按钮
English · depth-of-field preview buttonEspañol · botón de previsionado de profundidad de campoFrançais · vérification de la profondeur de champ
释义：Button that closes the diaphragm so that the relative clarity of various depths can be seen through the viewfinder.