Real-image variable magnification view finder

Details Real-image variable magnification view finder Real-image variable magnification view finder

1998-09-22

2000-03-07

Metjahic, Safet

Photography

With viewfinder

Selective or adjustable viewfinder field

396384, 396386, 359432, 359686, G02B 1514, G02B 2300, G03B 1310

Patent

active

060351454

ABSTRACT:
A real-image variable magnification finder includes an objective optical system of positive power, a condenser lens located at an image forming surface of the objective optical system, an eyepiece optical system of positive power, and an image erection optical system. The objective optical system of positive power includes a first positive lens group, a second negative lens group, a third positive lens group, and a fourth negative lens group. Upon change of magnification from the low magnification extremity to the high magnification extremity, the second lens group is moved to monotonically increase the distance between the second lens group and the first lens group; and the third lens group is moved to monotonically increase the distance between the third lens group and the fourth lens group while the first and fourth lens groups are kept immovable. The finder satisfies the condition defined by (1) 1.2<m.sub.4 <2, wherein m.sub.4 represents the lateral magnification of the fourth lens group.

REFERENCES:
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patent: 5309278 (1994-05-01), Ito et al.
patent: 5376984 (1994-12-01), Abe
patent: 5434636 (1995-07-01), Hasushita et al.
patent: 5513043 (1996-04-01), Abe et al.
patent: 5541768 (1996-07-01), Ito et al.
patent: 5550674 (1996-08-01), Abe et al.
patent: 5694244 (1997-12-01), Abe et al.
patent: 5793529 (1998-08-01), Abe et al.

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