| 摘要 |
PURPOSE:To accurately perform focusing even under the periodical fluctuation of the quantity of incident light to an image pickup device by generating absolute value data by detecting the level of a high frequency band component, and calculating a focus evaluation value by performing the estimation of the absolute value data at every plural fields. CONSTITUTION:An estimation circuit 12 generates the focus evaluation value by adding the absolute value data from an absolute value data generating part 6. A counter 17 counts the pulse of a vertical synchronizing signal, and outputs a reset pulse to reset a latch circuit 12b in the estimation circuit 12 at every count of three pulses. Therefore, since data held in the latch circuit 12b is reset at every three field periods, the focus evaluation value of the estimation circuit 12 goes to a value on which all the absolute value data of three fields are added. Thereby, the level fluctuation of the high frequency band component of a luminance signal generated when the quantity of incident light to an image pickup element fluctuates up and down periodically can be uniformized when the focus evaluation value is calculated, therefore, accurate focusing can be performed even when the light quantity of a light source fluctuates periodically. |
