| 摘要 |
PURPOSE:To prevent the condition of being out of focus due to the movement of an object by detecting the movement of the object upon a focal plane so that the shutter time second may be automatically determined in accordance with the moving velocity. CONSTITUTION:Let is be assumed that the brightness of an object which is obtained from a photometric circuit is at a level of EV 15. In this instance, the shuter time second information Tv ''min and Tv'' max for ensuring proper exposure are calculated in accordance with the iris aperture information Avmax and Avmin fed from the lens and the Ev value. Then, the ranges Tv' min and Tv' max of the shutter time second, which are restricted by a shutter mechanism, are compared with the calcualted results so that the shortest and longest information Tvmax and Tvmin of the shutter time second corresponding to the EV value is selected within the iris and shutter time second coacting range, as shown in hatched lines. Here, Tb and Tc of the Drawing are selected in accordance with the shutter time second T' which is preset manually. If the selected values are located out of the coactive range, the approximate extreme values Ta''' and Tb''' are selected as the shutter time second. |
