Minolta Camera Kabushiki Kaisha

Mitsuaki Horimoto

Tohru Matsui

Kayoshi Tsujimoto

Haruo Abe

Masaichi Shimomura

The present invention is directed to a three-group type wide angle zoom lens system which comprises, from the object to the image side, a first lens group of a negative refractive power movable along the optical axis for zooming, the first lens group including at least two positive lens elements and at least one negative lens element, a second lens group of a positive refractive power movable separately from the first lens group along the optical axis for zooming, the second lens group being of the triplet type formed by sandwitching a negative refractive power component in between a pair of positive refractive power components, and a third lens group of a positive refractive power movable separately from the first and second lens groups along the optical axis for zooming, the third lens group including at least one positive lens element, wherein the lens system fulfills the following condition:

Zoom lens system

An improved compact high-speed fish eye lens system with minimal saggital flare is provided. The lens system comprises a front lens group having a pair of negative meniscus lens elements convex to the object side, an intermediate lens group having a pair of positive lens elements and a negative lens element, a rear lens group having a pair of doublets, the object side one of which includes an intermediate cemented surface having a positive refractive power. The radius of curvature, R, of the intermediate cemented surface of the object side doublet fulfills the following conditions wherein f represents the focal length of the whole lens system:

Fish eye lens system

An improved high speed fish eye lens system is provided capable of compensating for lateral chromatic aberration, field curvature and astigmatism while providing an aperture ratio of F/2.8. The fish eye lens system includes a first lens group of a negative refractive power having two negative meniscus single lenses convex to the object side. A second lens group of a positive refractive power includes a doublet, while a third lens group of a positive refractive power includes at least a positive meniscus single lens convex to the image side and a doublet.

A wide angle zoom lens system for use with a 35 mm single lens reflex camera is provided. The zoom lens system is relatively compact and includes two lens groups that can be relatively displaced along the optical axis to provide variation in focal length as desired. The first lens group has a negative refractive power and the image side second lens group has a positive refractive power. The relationship of their refractive powers has been selected to provide adequate correction of aberrations while maintaining the size, weight and compactness required in a modern zoom lens system with wide angle capability.

Two group wide angle zoom lens system

An extremely wide angle or fish eye lens system is provided capable of compensating for lateral chromatic aberration, field curvature and astigmatism while providing an aperture ratio of F/4 for use with a compact single lens reflex camera. The fish eye lens system includes a first lens group of four lenses on the object side of a diaphragm and a second lens group of at least three lenses on the image side of the diaphragm. From the object to image side, the first lens group includes a pair of negative lenses, a cemented doublet and a positive fourth lens having a convex surface on the image side adjacent a concave surface of the cemented doublet. The second lens group includes a pair of cemented doublets as two of the three lenses.

A varifocal lens assembly of a type including at least two lens groups, a first lens group being axially movable parallel to the optical axis of the varifocal lens assembly for varying the focal length of the optical system of the varifocal lens assembly. An automatic focusing device is associated with the varifocal lens assembly to axially move the lens groups as a whole, the other or second lens group or a part of lens elements of the other or second lens group a predetermined distance to compensate for the image shift which takes place during the adjustment of the focal length effected by axially moving the first lens group.

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Osaka, Japan

Mitsuaki Horimoto