| 摘要 |
<p>PURPOSE:To obtain correct exposure despite successive opening of an aperture to full aperture side in close-up flash photographing by providing a correction circuit which makes the generation timing of a dimming signal forcedly earlier than the value determined by a photographical rule. CONSTITUTION:If the aperture is changed to full aperture side where film sensitivity information is made constant and a distance ring is fixed at the closest distance, a variable resistance 5 changes according to its change. The voltage value by the resistance value of this resistance 5 is inputted together with the voltage value by other information to a subtracter constituted of an operational amplifier 57 and the like. Now, the film sensitivity is kept constant and the object distance is also fixed, and therefore, the top end voltage of a resistance 58 changes with the aperture information alone. Here, when the value of the variable resistance 5 decreases, namely, when the aperture approaches to the full aperture, the top end voltage of the resistance 58 lowers and the voltage drop of a resistance 60 decreases, thus escaping from a clamp region. Hence, the potential of a capacitor 50 which is reference voltage rises and generates the dimming output earlier than the theoretical value. With such constitution, correct exposure is obtained.</p> |
