Optical: systems and elements – Lens – With variable magnification
Patent
1996-05-23
1998-06-09
Epps, Georgia Y.
Optical: systems and elements
Lens
With variable magnification
359684, 359685, 359688, G02B 1514
Patent
active
057644209
ABSTRACT:
A zoom lens comprising five lens groups is configured such that the total moving amount of the second lens group from the wide angle end to the telephotographic end is changed according to the object distance and that the fourth lens group is moved so as to correct zooming and focusing, whereby the imaging magnification is prevented from decreasing at the time of zooming even when the object distance changes. It comprises five lens groups respectively having positive, negative, negative, positive, and positive refractive powers. At the time of zooming, the first, third, and fifth lens groups (G1, G3, and G5) are fixed, while the second and fourth lens groups (G2 and G4) are made movable. The second lens group (G2) is moved in the optical axis direction so as to change the focal length of the whole system, while the fourth lens group (G4) is moved in the optical axis direction to correct fluctuation in the imaging position and to correct change in the imaging position caused by change in the object distance. The moving amount of the second lens group (G2) at the time of zooming is made larger when the object is placed at a close telephotographic position than when the object distance is at an infinite telephotographic position.
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Epps Georgia Y.
Fuji Photo Optical Co., Ltd.
Lester Evelyn A.
Snider Ronald R.
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