Two-group zoom lens

Details Two-group zoom lens Two-group zoom lens

1996-11-04

1998-10-20

Epps, Gorgia Y.

Optical: systems and elements

Lens

With variable magnification

359691, G02B 1514

Patent

active

058255575

ABSTRACT:
In a compact two-group zoom lens composed of a positive front group (G.sub.1) and a negative rear group (G.sub.2), the rear group (G.sub.2) is constituted by negative, positive, and negative lenses, thereby improving productivity while attaining a high magnification of about 3.times.. The zoom lens is constituted by the front group (G.sub.1) comprising four sheets of lenses (L.sub.1 to L.sub.4) and the rear group (G.sub.2) comprising three sheets of lenses (L.sub.5 to L.sub.7). The rear group (G.sub.2) has the fifth lens (L.sub.5) made of a biconcave plastic lens having aspheric surfaces on both sides, whose surface with a stronger curvature is directed onto the object side on the optical axis (X); the sixth lens (L.sub.6) made of a biconvex lens having a surface with a stronger curvature directed onto the object side; and the seventh lens (L.sub.7) made of a negative meniscus lens having a concave surface directed onto the object side.

REFERENCES:
patent: 4844600 (1989-07-01), Tokumaru
patent: 4936661 (1990-06-01), Betensky et al.
patent: 5082360 (1992-01-01), Sato et al.
patent: 5646787 (1997-07-01), Kamo

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