Variable power finder and imaging apparatus

Details Variable power finder and imaging apparatus Variable power finder and imaging apparatus

2006-01-10

2006-01-10

Nguyen, Thong Q (Department: 2872)

Optical: systems and elements

Compound lens system

Telescope

C359S432000, C359S689000

Reexamination Certificate

active

06985289

ABSTRACT:
A variable power finder is proposed, which comprises: an objective system; an inverting system; and an ocular system, in order from object side. The third lens group of the objective system is constituted by one lens prism having at least one reflection surface, and following expressions are satisfied:in-line-formulae description="In-line Formulae" end="lead"?f3/fw≧2.5  (1)in-line-formulae description="In-line Formulae" end="tail"?in-line-formulae description="In-line Formulae" end="lead"?−1.0<(R32+R31)/(R32−R31)<1.0  (2)in-line-formulae description="In-line Formulae" end="tail"?in-line-formulae description="In-line Formulae" end="lead"?L1/fw2≦0.45 1/mm  (3)in-line-formulae description="In-line Formulae" end="tail"?in-line-formulae description="In-line Formulae" end="lead"?L2/fw2≧0.03 1/mm  (4)in-line-formulae description="In-line Formulae" end="tail"?where f3is a focal distance of in millimeters (mm) third lens group, fw is a focal distance in mm at wide angle end of objective system, R31is a curvature radius of object side lens surface of lens prism, R32is a curvature radius of image side lens surface of lens prism, L1is an air equivalent distance in mm from middle imaging surface to object side lens surface of lens prism, and L2is a distance in mm from middle imaging surface to image side lens surface of lens prism.

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