| 摘要 |
PURPOSE:To obtain a zoom lens with simple construction and good accuracy, by providing a guide means guiding and displacing the 1st group lens holding cylinder toward light axis for focusing, and operating means displacing the 2nd group lens toward light axis for magnification. CONSTITUTION:In the 1st group lens holding cylinder 9, straight keys 9a, 9b are slidably inserted to key grooves 4e, 4f of a cam ring 4, and the cylinder 9 turns incorporatedly when the cam ring 4 turns. Since a guide cylinder 10 is inhibited for rotation with two straight bars 10a, 10b, the cylinder 9 causes displacement toward light axis through the operation between a cam groove 9c and a steel ball 11 to shift a lens L1 and to correct focus plane movement. A moving ring 5 holding a magnification lens L2 is guided straightly toward optical axis with guide bars 7a, 7b. With this constitution, a zoom lens with simple construction and good accuracy can be obtained. |
