| 摘要 |
PROBLEM TO BE SOLVED: To obtain a zoom lens allowing detection of a high-accuracy focus detection signal and observation of a taken picture concurrently without being influenced by the insertion/pulling-out of an extender lens in/from an optical path. SOLUTION: The zoom lens has: a focusing part including a lens group for focusing; a variable power part including two lens groups moving on an optical axis for the purpose of zooming; an aperture stop for restricting passing light quantity; and an image-formation part including a lens group for image-formation in order from an object side to an image side. The image-formation part has: a lens group L21 including a branching element for branching incident luminous flux into a plurality of optical paths; a lens group L22 inserted in/pulled out from one of the plurality of optical paths, and at least one lens group L22ex which can be replaced with the lens group L22 in order to make the focal distance range of an entire system different from each other; and a lens group L23 having positive refractive power. COPYRIGHT: (C)2007,JPO&INPIT
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