Zoom lens system
AssigneeOlympus Optical Co., Ltd.
InventorYasuji Ogata
Life of this patent
Estimating the term…
Abstract
A zoom lens system comprising a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having positive refractive power wherein the fourth lens group comprises a positive, positive and negative lens components, the zoom lens system having a large zoom ratio and large aperture ratio, i.e., F/5.0, and being compact in size and low in price.
Claims9
A zoom lens system comprising, in the order from the object side, a first lens group having a positive refractive power and comprising a positive cemented doublet, a second lens group having negative refractive power and comprising two negative lens components and a positive lens component, a third lens group having positive refractive power and comprising a cemented doublet, and a fourth lens group having a positive refractive power, and said fourth lens group, which is arranged to be the rearmost lens group, consisting of a positive lens element, a positive lens element and a negative lens element, the airspaces between said lens elements constituting the fourth lens group being constant, and the airspace between said third lens group and fourth lens group being variable at the time of zooming.
A zoom lens system comprising, in order from the object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having positive refractive power, said fourth lens group comprising a positive lens element, a positive lens element and a negative lens element in the order from the object side, said first lens group comprising a positive cemented doublet and a positive lens component, said second lens group comprising a negative lens component, a negative lens component and a positive cemented doublet and said third lens group comprising a positive lens component and a positive cemented doublet, said system fulfilling the conditions (1) through (4) shown below:
- ##EQU2## where, reference symbol f.sub.T represents the focal lengths of the lens system as a whole in the teleposition, references symbols f.sub.2 and f.sub.4 respectively represent the focal lengths of the second lens group and the fourth lens group, reference symbol d.sub.9 represents the airspace between the negative lens component and the image side and positive cemented doublet in the second lens group, reference symbol r.sub.22 represents the radius of curvature of the surface on the object side of the negative lens component in the fourth lens group.
Dependencies are inferred from the claim text.