| 摘要 |
PURPOSE:To form an excellent picture of desired magnification by adjusting focal length through a focal-length adjusting means engaging a zoom ring while holding the zoom ring at a reference position. CONSTITUTION:An eccentric pin 17 fixed to a holding cylinder 16 is engaged slidably with a long cam hold 19 made in a lens barrel 15 for holding a lens G1, and the head of the eccentric pin 17 is engaged mutually slidably in a long hole 21 made in the zoom ring 20. When the zoom ring 20 engaged with the lens barrel 15 rotatably and slidably is rotated, the holding cylinder 16 holding lenses G2-G4 move in an optical-axis direction by the extent of rotation of the pin 17 and an extent corresponding to the shape of the cam hole 19 to perform zooming operation. When the eccentric pin 17 is rotated around a screw 18 while a ball 24 is positioned in the recessed part 22 of the zoom ring 20, the holding cylinder 16 moves finely in the optical-axis direction to adjust the focal length. Therefore, the rotation position of the zoom ring is made to correspond to the focal length accurately. |
