| 摘要 |
PURPOSE:To improve the accuracy of focus detection for an object corresponding to the center of a screen and a position distant from it by arranging three photodetecting element arrays corresponding to at least secondary image-forming lenses, selecting two optional photodetecting element arrays according to the signal from an input means, and utilizing the output signals of those two photodetecting element arrays. CONSTITUTION:An optical means is provided with at least one field lens which is arranged nearby a plane equivalent to the image formation plane of an objective 1 and the three secondary image forming lenses 41-43 arranged at least linearly in a plane perpendicular to the optical axis of the objective 1. Then the optical axis of the center secondary image forming lens among the three secondary image forming lenses 41-43 is aligned nearly with the optical axis of the objective 1 and a photodetecting means is provided with the three photodetecting element arrays 51-53 corresponding to the three secondary image forming lenses 41-43. Two optical photodetecting element arrays are selected among those three photodetecting element arrays 51-53 by an input means and its output signal is used to perform focus detection at an optional position in the screen. Consequently, the focus detection for a position distant from the center of the screen is performed with high accuracy. |
