| 摘要 |
PURPOSE:To make always full-aperture photometry possible, by detecting stopping-down of an aperture and controlling a stepping motor before the release operation to return the aperture to the open state. CONSTITUTION:If an aperture AP has a certain aperture value by some cause in the initial state of photometry, clock pulses from a pulse generator CG1 are inputted to a stepping motor driving circuit DR through an OR gate O1 because a switch SW2 is opened. Since a switch SW1 is opened because of photometry, the output of an inverter I3 given to a terminal LE of the driving circuit DR becomes high-level. Then, a stepping motor SM is rotated counterclockwise to return the aperture to the open state. Thus, full-aperture photometry is always possible. |
