Minolta Camera Kabushiki Kaisha

Minolta Camera Co., Ltd.

Kazuyoshi Hata

Masami Tanaka

Katsuhiro Takamoto

Yukio Maekawa

Manami Saka

Sachiko Takamura

A zoom lens system according to the present invention comprises, from the object side to the image side, a first lens unit with a positive refractive power including a negative high dispersion lens element and a positive lens element; a second lens unit with a negative refractive power consisting of two or three lens elements including a positive high dispersion lens element and a negative lens element, and having at least one aspherical surface; and a third lens unit with a positive refractive power consisting of five or less lens elements including a negative high dispersion lens element and one or two positive lens elements located on the object side of the negative high dispersion lens element, and having at least one aspherical surface. With the lens arrangement, a compact high-zoom-ratio zoom lens system having a high aberration correction performance is realized.

Zoom lens system

A zoom lens system comprises from the object side to the image side: a first lens unit of a positive refractive power; a second lens unit of a negative refractive power; and a third lens unit of a positive refractive power; wherein one of the first and third lens units is shiftable along the optical axis of the lens system in both of the zooming operation and the focusing operation, and the second lens unit is also shiftable along the optical axis of the lens system in the zooming operation.

The present invention provides a compact zoom lens having a zooming ratio of six (6) to eight (8) and an F-number of 1.4 to 1.6, and comprising from the object side; a first lens unit of a positive refractive power and consisting of, from the object side, a first negative meniscus lens element convex to the object side, a second positive lens element, located at the image side of the first negative meniscus lens element with having an air space therebetween, having a stronger refractive surface on its object side surface; a second lens unit of a negative refractive power and consisting of, from the object side, a third negative lens element having a stronger refractive surface of its image side surface, and a fourth positive lens element, located at the image side of the third negative lens element with having an air space therebetween, said second lens unit including an aspheric surface; a third lens unit of a positive refractive power and consisting of a single positive lens element having an aspheric surface; and a fourth lens unit of a positive refractive power and including a positive lens element and a negative lens element; and the second lens unit being shiftable in the zooming operation and at least one of the first, third and fourth lens unit being also shiftable in the zooming operation.

A compact zoom lens system comprising from the object side to the image side, a first lens unit of a negative refractive power having a cemented lens component consisting of a negative lens element and a positive lens element cemented with each other, said first lens unit being shiftable along an optical axis of the lens system in zooming operation, a second lens unit of a positive refractive power having two positive lens components, at least one of which consists of a positive lens element and a negative lens element cemented with each other, said second lens unit being shiftable along the optical axis of the lens system in the zooming operation and a third lens unit of a positive refractive power having from the object side, a front lens component of a negative refractive power and a rear lens component of a positive refractive power, said third lens being stationary along the optical axis of the lens system in the zooming operation, in order to realize a zooming ratio of about two or three, a very short overall length and a light weight while having a large aperture by a configuration with a small number of lens elements.

Compact zoom lens system

A zoom lens system comprises from object side to image side, a front lens unit of a negative refractive power and a rear lens unit of a positive refractive power with a variable air space, which changes in the zooming operation, formed between the front and rear lens units. The rear lens unit consists of a first biconvex lens element, a second biconcave lens element and a third biconvex lens element. Futher, an aperture diaphragm, which is arranged between the front and rear lens units or at the image side next to the rear lens unit, is stationary on the optical axis of the lens system in the zooming operation. In a 2-components zoom lens system having a negative lens unit and a positive lens unit from object side according to the present invention, a zoom ratio of about 2 and a sufficiently long back focal length can be obtained in spite of a small number of lens elements. Moreover, cost reduction, compactness and a high performance in the whole lens system including the aperture diaphragm and a lens barrel are obtainable.

The present invention provides an objective lens system for optical recording type disks, comprising from a light source side to a disk side; a first lens element having a positive refractive power, said first lens element having at least an aspherical surface; a second lens element having a positive refractive power; and wherein the objective lens system fulfills the following condition:

Objective lens system for optical recording type disks

A large aperture ratio zoom lens system is provided for use in a video camera. The lens system includes a first lens unit of a positive refractive power, a second lens of a negative refractive power, a third lens unit of a negative refractive power, a fourth lens unit of a positive refractive power, an aperture diaphragm, and a fifth lens unit of a positive refractive power. A second lens component in the fifth lens unit has a strong negative refractive power and has a capability to correct field curvature as well as spherical aberrations.

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Osaka, Japan

Kazuyoshi Hata