| 摘要 |
<p>1450633 Cameras POLAROID CORP 10 June 1974 [5 July 1973] 25631/74 Heading G2 A A camera, when used for flash photography, has its exposure aperture and exposure time set in dependence on the focusing of the lens such that, at predetermined intermediate subject distances (typically around 4 feet) the exposure time lasts for most of the flash illumination interval and, for a given subject, is larger than the exposure times at slightly greater and slightly smaller distances. As shown, shutter-diaphragm blades 24, 26 open to an extent dependant on a follow-focus arrangement Figs. 3, 4, 5 (not shown), whereby apertures 36, 38 define on exposure aperture dependant on subject distances and apertures 56, 58 define a photo-cell aperture dependant on subject distance to control an exposure time determining light integrating unit; apertures 56, 58 being shaped to provide the required exposure time control at subject distances around 4 feet. It is stated that such control is necessary because at intermediate subject distances neither the subject nor the background dominates the exposure and the integrating unit tends to produce erroneous exposure times. By utilizing most of the flash illumination interval, the effect of such errors is reduced.</p> |
