| 摘要 |
PURPOSE:To prevent focus detection accuracy from decreasing by arranging a luminous flux limiting member between a visual field mask and a secondary image forming lens and determining the size of opening parts so that the margin area of an opening part outside effective luminous flux is larger in the separation direction of a secondary image than in a direction perpendicular to it. CONSTITUTION:The luminous flux limiting member (aperture 18) is arranged between the visual field mask 10, and secondary image forming lens and an aperture lens 12, and the size of the opening part is so determined that the margin area of the opening part outside the effective luminous flux is larger in the separation direction of the secondary image 15b than in the direction perpendicular to it. Namely, the opening sides 18<-1> and 18<-3> of the stop in the two-image splitting direction are given an enough margin from the effective luminous flux and the opening sides 18<-2> and 18<-4> have no margin from the effective luminous flux. Therefore, even if ghosts 19b<-3> and 19a<-1> appear on line sensors 14a and 14b, light beams which form the ghosts are made incident very slantingly to the optical axes. Consequently, a decrease in focus detection accuracy due to the ghosts is eliminated. |
