| 摘要 |
PURPOSE:To detect always satisfactorily focusing by evaluating the threshold value of a change-over function for changing over a method for detecting an out-of-focus image and a method for detecting a lateral deviation in accordance with the decision function changing with the F-number of an imaging lens. CONSTITUTION:The relation between an F-number and the rate of a lateral deviation is the equation I when the F-number is expressed by F and the rate of the lateral deviation by Z if there are photodetector arrays 11, 12 in the position apart by a specified distance DELTA from the imaging position by a photographing lens 1. Lateral deviation functions Y1, Y2 attain therefore the values inversely proportional to the F-number with the same subject in the range of the rate of deviation within the calculated rate of deviation. Decision of whether the imaging position of the subject by the lens 1 enters the regions between positions 13A and 13B or not is performed and in the case of Y1XY2>0, the focusing detection by the out-of-focus image is inaccurate and therefore the evaluation by the lateral deviation function Y is accomplished. The evaluation of the F-number by the decision function H is accomplished by judging that the imaging position is between the positions 13A and 13B in the case of Y1XY2<0. |
