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US Patent 5734509 - Zoom lens system
US Patent Issued on March 31, 1998
Estimated Patent Expiration Date:
September 13, 2016Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
Estimated Patent Expiration Date:
September 13, 2016Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.AbstractA zoom lens system is composed of three lens groups. Arranged in the order from an eyepoint side are a first lens group G1 having a positive refracting power, a second lens group G2 having a positive refracting power and movable along an optical axis during the period of zooming, and a third lens group G3 having a negative refracting power and movable along the optical axis during the period of zooming. In the second lens group G2, at least one positive lens includes a lens surface composed of an aspheric surface at least on one of its eyepoint side and object side. Not only a sufficient eye relief is ensured but also various aberrations are corrected throughout the whole zooming range. | InventorAssigneeApplicationNo. 713592 filed on 09/13/1996US Classes:359/689, Three groups359/399, Telescope359/422, Variable magnification359/645, Having three components359/716Having three componentsField of Search359/689, Three groups359/645, Having three components359/716, Having three components359/791, + + - Arrangement359/399, Telescope359/422Variable magnificationExaminersPrimary: Nelms, David C.Assistant: Lester, Evelyn A. Attorney, Agent or FirmForeign Patent References
International ClassesG02B 015/14G02B 025/00 G02B 023/00 G02B 013/10 Foreign Application Priority Data1992-12-09 JP |
