| 摘要 |
PURPOSE: To accurately obtain the moving speed of an image surface by calculating it based on the focusing state of a converted object position and the focusing state at a second time. CONSTITUTION: By a photographing lens 1, luminous flux from an object 2 is guided to a main mirror 3. By the mirror 3, one part of the luminous flux from the lens 1 is reflected on a reticle and the other part is transmitted. By a sub-mirror 4, the luminous flux transmitted through the mirror 3 is reflected and guided to an AF module 5. Based on the positions LP1 and LP into of the lens 1 respectively detected at the first time t1 and at the second time t0 and the extending amount DP1 thereof, the focusing state of the object position is converted to that of the first time t1 at the position of the lens 1 of the second time t0. Since the moving speed of the image surface is calculated based on the o converted focusing state of the object position and the focusing state at the second time t0, it is accurately calculated. |
