| 摘要 |
PURPOSE:To obtain a large-aperture ratio zoom lens excellent in aberration correction, by constituting the optical system of the zoom lens of four lens groups having a positive, negative, negative, and positive refractive indexes from the object side, and making the optical system to satisfy a prescribed condition. CONSTITUTION:The 41-th lens group IV1 is composed of the 411-th lens having a positive refracting power, 412-th lens having a positive refracting power, 413-th lens having a negative refracting power, and 414-th lens having a positive refracting power, and the 42-th lens group IV2 is composed of the 421-th lens having a negative refracting power, 422-th lens having a positive refracting power, and 423-th lens having a positive refracting power. The optical system is made to satisfy the conditions of formulae I -V. The RIVi of the formulae represents the radius of curvature of the i-th lens surface counting from the object side of the 4th lens group IV1 and IV2 and the DIVi represents the i-th lens thickness or air interval. The fW represents the focal length of the entire system at the zoom position of the wide angle end. |
