| 摘要 |
PROBLEM TO BE SOLVED: To provide an electronic camera capable of efficiently and precisely performing an automatic focus control of a downhill method in consideration of the effect of high frequency noise. SOLUTION: The digital video camera 10 captures the black level of a video signal during initializing process, in advance. When an automatic focus process is started, the digital video camera 10 captures an AF evaluation value and luminance evaluation value at the current position of a compensator lens 150. Then, the maximum AF evaluation value and the position of the compensator lens 150 at that time are updated. In addition, an AGC gain is captured. The offset value of the AF evaluation value is calculated by using the AGC gain, the luminance evaluation value and the black level. A threshold is calculated, based on this value and the maximum AF evaluation value. If the AF evaluation value is smaller than the threshold, the lens position at which the maximum AF evaluation value is deemed as being a focusing position, and is controlled. If the AF evaluation value exceeds the threshold, the compensator lens 150 is moved by a predetermined number of steps, and the processing described above is performed again. COPYRIGHT: (C)2008,JPO&INPIT |
