| 摘要 |
PROBLEM TO BE SOLVED: To improve accuracy of focal point detection by a simple circuit configuration. SOLUTION: A pixel signal outputted from a focal point detection sensor is A/D converted with an accuracy of 10 bits. A re-integration flag is 0 at the beginning. Therefore, the pixel signal is converted from 10 bits into 8 bits (step S316). The maximum value and the minimum value of the pixel signal are obtained (step S317) and the pixel signal is stored in a memory (step S321). Contrast is calculated together with calculation of defocusing (step S325). The re-integration flag is determined as 1 when the contrast is low, and the amount of the shift is obtained (steps S327, S329). Next, an integral action of the focal point detection sensor is performed again, to obtain the pixel signal. After the pixel signal is A/D converted with an accuracy of 10 bits, it is converted into 9 bits (step S312), a shift amount is subtracted from it to be converted into a data length of 8 bits (step S313). |
