Optical: systems and elements – Compound lens system – Telescope
Patent
1994-06-14
1996-10-29
Nguyen, Thong
Optical: systems and elements
Compound lens system
Telescope
359421, 359422, 396379, 396386, G02B 2300, G03B 1308
Patent
active
055702295
ABSTRACT:
A real image mode variable magnification finder optical system is provided with an objective lens having a positive refracting power and an eyepiece having a positive refracting power. The objective lens includes the first lens unit having a negative refracting power, the second lens unit having a positive refracting power which is movable for varying magnification, and the third lens unit having a positive refracting power which is movable for varying magnification. Moreover, the objective lens has the first reflecting surface for erecting an image on the entrance side of the region of a space provided on the object side of the second lens unit to move lenses when a change of magnification is made, and the second reflecting surface for erecting the image between the third lens unit and an intermediate imaging plane. Thus, the finder optical system brings about a reduction of thickness of a camera body, favorable correction for aberration, and cost reduction.
REFERENCES:
patent: 3658411 (1972-04-01), Price
patent: 4906078 (1990-03-01), Inabata et al.
patent: 5311355 (1994-05-01), Kato
patent: 5491328 (1996-02-01), Takato et al.
English Abstract of Mukai et al Japenese laid open Application No. 3-287216, Dec, 1991.
Nguyen Thong
Olympus Optical Co,. Ltd.
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