| 摘要 |
PURPOSE:To confirm the depth of field without spoiling brightness greatly by placing a variable focus plate element in a translucent state and putting a lens in focus in automatic focusing mode, and driving the element into a diffusion state when focusing is disabled or in manual focusing mode. CONSTITUTION:The variable focus plate element 114 is driven into the translucent state in the automatic focusing mode to put the lens in focus or into the diffusion state when focusing is disabled or in the manual focusing mode. When the depth of field needs to be confirmed, the variable focus plate element 114 is put in the diffusion state corresponding to the kind and stopping value of the lens 111 after the focusing. Consequently, a bright and sharp finger image which has no decrease in light quantity is obtained in the automatic focusing mode and when the focusing is disabled or when the manual focusing mode is selected, the extent of defocusing is easily confirmed and the depth of field can be confirmed without spoiling the brightness. |
