| 摘要 |
<p>A camera has shutter-diaphragm blades (40, 42) openable to define a primary aperture (46-48) for passing light to the film plane and a secondary aperture (50-52) for passing light to a photodetector (58) for controlling exposure; the blades also being arranged to admit light to the photodetector before exposure for indicating whether the brightness is adequate for exposure without flash. Preferably, a visual indication is given by means of a LED, and preferably if the brightness is not adequate, operation of the camera without flash is inhibited. The passage of light to the photodetector before exposure may be allowed by a third aperture (54- 56) in the blades, or by an extension of a secondary aperture (59, Figure 7 not shown). In another form, two blades (40,42, Figures 2a to 4a not shown) are contoured to provide tabs (54', 56') which are spaced before exposure to allow light to reach the photodetector along a path, distinct from the path provided by the secondary aperture. Alternatively, an aperture controlling the light path to the photodetector may be provided in an independently operable third blade. <IMAGE></p> |
