摘要 |
Method and apparatus for detecting a focus condition for an optical system sequentially forms two images of an object, the images propagating along two different optical paths. The two images are sequentially received with a plurality of photosensitive elements. The photosensitive elements are disposed in a plurality of sections, each section having a plurality of elements, each element outputting a signal corresponding to received light. The element output signals from the first image are stored in a first memory, while the element output signals from the second image are stored in a second memory. A processor calculates the image light contrast for each section from the stored element signals. Then, the section displaying the highest contrast is selected for use in the correlation process. The correlation process is carried out by correlating the stored first image element signals with the stored second image element signals from the selected section. From the correlation process, the focus condition of the optical system is readily determined.
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