| 摘要 |
PURPOSE:To stabilize the distance detection of a camera which uses different focal lengths, by controlling the luminous intensity of a light source and the output amplification factor of a photodetector according to variation in lens focal length. CONSTITUTION:In response to release operation, motor Mt displaces a photographic lens to deflect reflex mirror M accordingly. Consequently, projected light from LED reaches object A scanning on the optical axis of lens L2 from the nearest distance to the far distance, and its reflected light is detected by photodetector S, whose output is supplied to motor Mt via amplifier Amp. Then, motor Mt stops to fix lens ZL3 corresponding to the distance of the object. In this case, the luminous intensity of LED is increased and the gain of Amp is determined corresponding to the focal length of the lens in use. Thus, the stable distance detection is performed. |
