| 摘要 |
PURPOSE:To accurately detect the best focus position by calculating the variance of data regarding the brightness of a subject by focus positions and regarding the maximum value of the variance as the best focus position. CONSTITUTION:A control circuit 6 calculates data of a signal (e.g. brightness signal) regarding the brightness of the subject stored on a memory 3 at intervals of a time (e.g. 100 ms) which is preset and inputted to a memory 9 to find its variance. When the best focus position is obtained, the widest distribution range of brightness is obtained, so the position where the variance becomes maximum is the best focus position. Namely, the variance of the data regarding the brightness of an image is calculated by the focus positions and the maximum value of the variance is regarded as a proper focus position. Consequently, the proper focus position is accurately detected without being affected by local brightness, etc. |
