| 摘要 |
PURPOSE:To discriminate whether a preset aperture value reaches a prescribed value or not, comparting signals from two circuits, which generate signals changing in accordance with the difference of the number of stages between the preset aperture value for every interchangeable lens and an open F value and that between a prescribed aperture value and the open F value, with a prescribed reference signal. CONSTITUTION:A photometric output circuit A1 which generates a prescribed reference signal, the first circuit which generates the first signal changing in accordance with the difference of the number of stages between the preset aperture value for every interchangeable lens and the open F value for the prescribed reference signal and consists of the first variable resistance R1 and the first constant current attracting source I1, and the second circuit which generates the second signal changing in accordance with the difference of the number of stages between the prescribed aperture value and the open F value for every interchangeable lens for the reference signal and consists of the second variable resistance R2 and the second constant current attracting source I2 are provided. The first signal and the second signal are compared in a comparator CP to discriminate whether the preset aperture value reaches the prescribed value or not on a basis of the output from the comparator CP. |
