| 摘要 |
PURPOSE:To decide on the accurate quantity of defocusing of an objective lens to any body by calculating the quantity of evaluation from outputs of sensors which detect two images varying in relative position relation according to a focus state, and detecting a far/close contention with this quantity of evaluation. CONSTITUTION:A field lens 2 is arranged on the same optical axis with a photographic lens 1 for making a focus adjustment, two secondary image forming lenses 3a and 3b are arranged behind the field lens 2, and sensor arrays 4a and 4b for photodetection are arranged further behind it. The sensor arrays 4a and 4b are composed of plural photoelectric converting elements respectively, and when the output of the (i)th photoelectric converting element is denoted as a(i) and b(i) and P is a positive number, the quantity U of evaluation is calculated from an equation. When this quantity U of evaluation is larger than a specific value, a decision on the far/close contention is made. |
