| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens which is thin in a thickness direction of a camera and has a wide angle of view and a high variable magnification ratio and has various aberrations satisfactorily corrected. SOLUTION: A fourth lens group G4 comprises only three positive, negative, and positive cemented lenses c1 to c3, whereby a group structure is simplified to be able to improve productivity. That is, when the fourth lens group G4 comprises three lenses, a configuration not using three cemented lenses causes decomposition into two or more lens elements, and error factors such as lens eccentricity and changes of lens intervals are increased. Especially, when the fourth lens group G4 is made thin in order to enhance compaction, eccentric error sensitivity of respective lens elements, surface shape error sensitivity, thickness/interval error sensitivity, etc. are increased to induce the necessity of very raising alignment precision and positioning precision in an optical axis direction, of respective lenses, whereby productivity is reduced. Use of three cemented lenses c1 to c3 has an advantage of relatively easily improving productivity because it is sufficient if one lens element is managed substantially. COPYRIGHT: (C)2007,JPO&INPIT
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