AN APPARATUS AND TECHNIQUE FOR DETECTING AND CONTROLLING THE FOCUSING OF AN OPTICAL SYSTEM BY IMAGE SHARPNESS AND LATERAL SHIFT TECHNIQUES

In a method and apparatus for detecting focus condition of an imaging optical system, the focus condition is detected in accordance with a combination of two different detection methods such as an image sharpness detection and an image lateral shift detection by using first and second light receiving element arrays for the image sharpness detection and a third light receiving element array for the image lateral shift detection. For making the construction of the apparatus compact and simple, these light receiving element arrays are formed on the same semiconductor substrate. Further a light flux dividing prism and a lenticular lens array are formed integrally with each other. According to the focus detection method of the present invention, it is possible to detect the focus condition for various kinds of subjects accurately over a wide range by using both the image sharpness detection and image lateral shift detection even in a range near an in-focus position.