| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a large-diameter, compact and high-performance focusing lens fixing a front group in focusing and having an exit pupil position satisfactorily separated from an image surface. <P>SOLUTION: The imaging lens includes in order from an object side to an image side: a first lens group Gr1 having a positive or negative refractive power; a second lens group Gr2 having a positive refractive power; and a third lens group Gr3 having a positive refractive power; and an optical aperture Stop disposed between the second group and the image surface. The focusing is performed by fixing the first lens group and moving the second lens group and the third lens group in the optical axis direction. When the focal length of the entire optical system when focused on infinity is F, the focal length of the first lens group is F1, the focal length of the second lens group is F2, and the focal length of the third lens group is F3, the following conditional expressions are satisfied: (1) 0.5<F2/F3<1.6, and (2) 6.0<¾F1¾/F<20.0. <P>COPYRIGHT: (C)2013,JPO&INPIT |
