FOCUS DETECTOR OF CAMERA

PURPOSE:To approximately calculate a minimum value using an autocorrelation result to perform highly accurate focus detection even in a bad condition. CONSTITUTION:Luminous flux from an object passing a photographing lens 11 is bisected by a mirror 12 inside a camera main body 10. One luminous flux bisected is led to an eyepiece part 15 through a screen 13 and a pentagonal prism 14. The other luminous flux bisected is reflected again by the mirror 16 and is led to a focus detecting optical system 17 which consists of a visual field diaphragm, a condenser lens, a diaphragm mask and an image reforming lens, and an image at a position corresponding to a range finding visual field is divided into two images. A solid-state image pickup element 18 is arranged in the vicinity of an image reforming surface receiving the two images formed by the focus detecting optical system 17, and a signal light-received is photoelectrically converted and a data is transferred to a microcomputer 19. The microcomputer 19 performs focus detecting calculation based on a detected data and a photographing lens 11 is consequently driven to a focusing position.