| 摘要 |
PURPOSE:To enable focus to be detected at the arbitrary portions in the field of view of the photographing optical system by providing the means of selecting one out of the plural photo detector groups disposed on the imaging plane so as to receive the respectively different portions of the images. CONSTITUTION:Respective photo detector groups 3a-3e are disposed on the imaging plane of a photographing optical system 1 for detecting foucs and receive respectively different images. The photo detector groups 3a-3e are selected by a select switch 5 and the illuminance signal of the selected photo detector group is supplied to a picture-element-distributing part 6. The picture-element-distributing part 6 fetches out the illuminances xn-1, xn, xn+1 of the three adjoining picture elements with respect to the respective picture elements and parallel supplies these subsequently to a local illuminance operating part 7. The local illuminance operating part obtains ¦Xn of the second order difference of the illuminances about xn and similarly obtains Xn for each n. A cumulation operating part 8 obtains the sum Y with respect to the Xn being inputted. The position where the value of Y becomes maximum may be detected as focus. |
