Optical: systems and elements – Compound lens system – Telescope
Patent
1996-03-05
1998-01-27
Nguyen, Thong
Optical: systems and elements
Compound lens system
Telescope
359422, 359432, 359686, G02B 2300, G02B 1514
Patent
active
057127271
ABSTRACT:
A real-image zoom finder has an objective lens having a positive refractive power, and an eyepiece lens which is used for observing a real image of an object formed via the objective lens and has a positive refractive power. The objective lens includes, in the order from the object side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, a third lens unit having a negative refractive power, and a fourth lens unit having a positive refractive power, and attains zooming by moving at least the second lens unit along the optical axis. The objective lens satisfies the following conditions:
REFERENCES:
patent: 4846562 (1989-07-01), Tokumaru et al.
patent: 5091739 (1992-02-01), Kawamura
patent: 5173806 (1992-12-01), Ogata
patent: 5191477 (1993-03-01), Abe et al.
patent: 5235460 (1993-08-01), Abe
patent: 5323264 (1994-06-01), Kato
Nguyen Thong
Nikon Corporation
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