| 摘要 |
PURPOSE:To make possible controlling of diaphargm aperture and achieve higher reliability, smaller size and lighter weight by using the stored values of the combinations of diaphragm apertures and focal lengths with respect to F values. CONSTITUTION:The rotating amount of a cam barrel 2 which determines the focal length of a zoom lens body 1 converted to a signal by a potentiometer P1, and this signal is the address input to an ROM4 via an A/D converter 3. The combinations of diaphragm apertures and focal lengths to obtain the minimum F value of the body 1 have been stored in the ROM4. The diaphragm aperture information is read out from the same by the focal length information and is analogically multiplied 6 by the signal corresponding to the F value having been manually set with a pontentiometer P2. The multiplied value is inputted to a servo amplifier 7, the output thereof is supplied to a diaphragm blade driving motor M. Hence, diaphragm blade 8 are effectively stopped down, and the desired F value is obtained. |
