| 摘要 |
<p>PURPOSE:To automatize correction of exposure by comparing and operating respective photometric values of the first photometric system, where the transmitted light of a photographic lens is transmitted through a focusing screen and is measured, and the second photometric system, where the transmitted light of the photographic lens is reflected on a shutter curtain without being transmitted through the focal plate and is measured, to calculate the transmittance of the focusing screen. CONSTITUTION:The transmitted light of a photographic lens 1a is measured by the first photometric system 2 before the first blind exposure. At this time, the transmitted light of the photographic lens 1a is reflected on a quick return mirror 2a and is amplified by an amplifier 5 and is inputted to a logarithmic compressor 6. When the first blind exposure is performed and the quick return mirror 2a is displaced to a rise position, the transmitted light of the photographic lens 1a is reflected on a shutter curtain 3b and is led to a TTL light receiving part 3a and is measured by the second photometric system 3. The difference between an object luminance voltage Bv1 just before the first blind exposure and that Bv2 just after the first blind exposure is calculated, and the calculated variation is compared with a certain quantity (a maximum light quantity variance allowable voltage DELTABvmax); and if the variation is smaller than this value, it is judged that (Bv1+Bv2)/2 and an object luminance voltage Bv are equal to each other.</p> |
