| 摘要 |
PURPOSE:To shorten the processing time of automatic focus adjustment by not operating a correcting circuit when a diaphragm value at photographing is larger than the specific diaphragm value for the using lens and operating the correcting circuit when the value is smaller than the specific value. CONSTITUTION:Electric supply to a microcomputer PRS is started by turning on a power source switch, and the photographing diaphragm value Av is determined based on the output of a light measuring sensor SPC by pressing down a release button to the first step. Successively, the computer PRS calculates the defocus quantity of the photographing lens based on the output of a focus detecting sensor SNS. Then, the diaphragm Av obtained by the light measurement is compared with a reference value Ao, and when the result is discriminated at Av<Ao, prediction is carried out. Lens driving is also conducted based on the defocus quantity immediately obtained when it is discriminated as Av>Ao. Thus, a predictive calculation which loses effect by focus depth is prevented and the processing time is shortened by discriminating whether to operate or prevent the predictive correction of the diaphragm value. |
