| 摘要 |
PROBLEM TO BE SOLVED: To obtain a focus detector constituted to prevent the occurrence of a rear focus illusion. SOLUTION: A CPU 51 is respectively inputted with information indicating an open aperture F value of a taking lens 81 and focal length from a lens CPU 83 and calculates a focusing zone as follow: 1. When the open aperture F value is smaller than 1, a front focus side zone width FrW is set at 20μm. 2. When the open aperture F value is greater than 4, FrW is set at 50μm. 3. In the range from 1 to 4 in the open aperture F value, the value meeting the open aperture F value between 20μm to 50μm is set. 4. When the focal length is shorter than 20 mm, the rear focus side zone width RwW is set at 1/4 of FrW. 5. When the focal length is longer than 80 mm, RwW is set at the same width as the width FrW. 6. In the range from 20 mm to 80 mm in the focal length, the value meeting the focal length from 1/4 of FrW to FrW is set. The CPU 51 moves the focusing lens by controlling the driving of a motor 54 in such a manner that the amount of defocusing is confined within the focusing zone. COPYRIGHT: (C)2005,JPO&NCIPI |
