Finding device of variable magnification
Patent 4779969 Issued on October 25, 1988. Estimated Expiration Date: 
July 3, 2006. Estimated 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.
July 3, 2006. Estimated 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.Patent References 696788 3227042 Varifocal lens system with macro-photography capabilities Three element varifocal lens systems Varifocal objective containing movable lens component of positive refractivity Patent #: 4018510 InventorsAssigneeApplicationNo. 06/881818 filed on 07/03/1986US Classes:359/422, Variable magnification359/432, Variable magnification359/643EyepieceExaminersPrimary: Henry, Jon W.Attorney, Agent or FirmInternational ClassesG02B 15/177 (20060101)G02B 23/14 (20060101) Foreign Application Priority Data1985-07-03 JPAbstractA variable magnification finder including from front to rear, a first lens unit of negative power, a second lens unit of positive power and a third lens unit of positive power, these three units constituting an objective lens of positive overall power, followed by an eyepiece lens of positive power, wherein a finder image formed by the first and second units near the third lens unit is observed by the eyepiece lens, and, with the other lens units being held stationary, the second lens unit is axially moved to vary the finder magnification.Other References
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