| 摘要 |
PURPOSE:To eliminate photometric errors owing to the differences in light reflectances between the curtain plane of a shutter and the plane of a photographing film by setting plural pieces of photodetectors selectively in a photodetecting state in conformity with the traveling positions of the front curtain of the shutter. CONSTITUTION:In the initial period when the front curtain of a shutter starts traveling, photodetectors P1 and P2 receive mainly the reflected light from the front curtain, and the photocurrents generated in these photodetectors P1, P2 are integrated through transistors Q1, Q2 in an integrating capacitor C1, so that the charging voltage increases gradually. When the front curtain of the shutter is going to end traveling, a photodetecting selection switch S3 is turned on and the other photodetector P2 is set in a non-photodetecting state, thus the integration of the photocurrents in the capacitor C1 is continued in accordance with only the photocurrent generated in the photodetector P1. When the charging voltage of the capacitor C1 attains a prerescribed voltage, and rear curtain travels, and the exposure of the subject image on the plane of a photographing film is completed. |
