| 摘要 |
PURPOSE:To obtain a zoom lens barrel for automatic focusing which has a simple structure and is easy to assemble, by controlling the rotation of a driving motor with a signal from a focus detecting part to stop the first lens group in the focus position. CONSTITUTION:The first lens group 2 as the front groups which is moved in the direction of the optical axis by a driving motor 14 and the second lens group 3 as the rear group which moved forward and backward in the direction of the optical axis by the zooming operation are provided. Further, a zoom lens barrel 1 for automatic focusing is provided with a focus detecting part 27, which is provided in a position optically conjugate with a photographic film face and receives the detection light consisting of a part of the light of an object incident to this film face to discriminate the focus state of the image of the object to the photographic film face, and a control circuit 55 which controls the rotation of the driving motor 14 by the signal from this focus detecting part 27 to stop the first lens group 2 in the focus position. |
