Real-image zoom finder with rotationally asymmetric surface

Details Real-image zoom finder with rotationally asymmetric surface Real-image zoom finder with rotationally asymmetric surface

1998-07-17

2000-03-21

Blankenship, Howard B.

Photography

With viewfinder

Selective or adjustable viewfinder field

396382, 359678, 359689, G03B 1710

Patent

active

060411937

ABSTRACT:
A high-performance real-image finder with a zoom objective optical system wherein a power is given to a reflecting surface of an image-inverting optical system to reduce the size in the direction of the thickness, and at the same time, a rotationally asymmetric surface is used in the image-inverting optical system to correct rotationally asymmetric decentration aberrations. The zoom objective optical system Ob has a first lens unit G1 of negative power, a second lens unit G2 of positive power, and a third lens unit G3 of positive or negative power. The real-image finder further includes an image-inverting optical system PP for erecting an intermediate image formed by the objective optical system Ob, and an ocular optical system Oc having a positive refracting power. At least one of reflecting surfaces S.sub.8 and S.sub.9 of the image-inverting optical system PP is a curved reflecting mirror having an optical power and has a rotationally asymmetric surface configuration that corrects decentration aberrations produced by the curved reflecting mirror.

REFERENCES:
patent: 3810221 (1974-05-01), Plummer
patent: 3836931 (1974-09-01), Plummer
patent: 5917656 (1999-06-01), Hayakawa et al.
patent: 5920428 (1999-07-01), Kim
patent: 5963376 (1999-10-01), Togino

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