| 摘要 |
PURPOSE:To increase a detection range by arranging a couple of photodetector arrays consisting of K each of photoelectric converting elements on both sides of a surface conjugate to an expected focal plane. CONSTITUTION:Subject light incident to a cameral through a lens 2 is reflected by a movable reflecting mirror 1 to reach a viewfinder. Light passed through the center translucent mirror part 1a of the mirror 1 is passed through a total reflection mirror 5 and split into two by a half-mirror 6; they illuminate photodetector arrays 8 and 9 positioned in front of and behind a surface conjugate to a film 10. Their outputs are A/D-converted by a circuit 15, and a central processing unit 16 obtains an evaluation function S as shown by formula, where am is a coefficient and Dm is the difference between a maximum and a minimum among (m) successive elements. On the basis of the formula, a focusing signal is supplied to a display 17 and an optical system driving control circuit 18 to drive the motor of a driver 19. |
