Zoom optical system and camera comprising the same

A zoom lens optical system comprising, in order from an object side thereof, a first lens group having positive refracting power and a second lens group having negative refracting power in which, for zooming from a wide-angle end to a telephoto end of the zoom lens optical system, the respective lens groups move toward the object side with a decreasing spacing between the first lens group and the second lens group, wherein:

• said first lens group consists of, in order from an object side thereof, a first lens component (U1) having negative refracting power, a second lens component (U2) having positive refracting power and a third lens component (U3) having positive refracting power wherein each lens component consists of a single lens or a doublet, while the following conditions are satisfied:
• 0.8<|fG1/f11|<3 (2)0.35<fG1/f12<3 (3)0.8<fG1/f13<3 (4)
• where fG1 is a focal length of the first lens group, f11 is a focal length of the first lens component, f12 is a focal length of the second lens component, and f13 is a focal length of the third lens component.

A zoom lens optical system comprising, in order from an object side thereof, a first lens group having positive refracting power and a second lens group having negative refracting power in which, for zooming from a wide-angle end to a telephoto end of the zoom lens optical system, the respective lens groups move toward the object side with a decreasing spacing between the first lens group and the second lens group, wherein:

• said first lens group comprises, in order from an object side thereof, a first lens component (U1) having negative refracting power, a second lens component (U2) having positive refracting power and a third lens unit (U3) having positive refracting power wherein the first lens component is a doublet consisting of a negative lens and a positive lens in order from an object side thereof, and the second lens component is a doublet consisting of a negative lens and a positive lens in order from an object side thereof.

A zoom lens optical system having a zoom ratio of 3 or greater and comprising, in order from an object side thereof, a first lens group having positive refracting power and a second lens group having negative refracting power in which, for zooming from a wide-angle end to a telephoto end of the zoom lens optical system, the respective lens groups move toward the object side with a decreasing spacing between the first lens group and the second lens group, wherein:

• said first lens group consists of, in order from an object side thereof, a first lens component (U1) that has negative refracting power and in which a surface located nearest to the object side is concave on the object side, a second lens component (U2) having positive refracting power, a third lens component (U3) having negative refracting power and a fourth lens component (U4) having positive refracting power wherein the respective lens components in the first lens group consist of a single lens or a doublet.

A zoom lens optical system having a zoom ratio of 3 or greater and comprising, in order from an object side thereof, a first lens group having positive refracting power and a second lens group having negative refracting power in which, for zooming from a wide-angle end to a telephoto end of the zoom lens optical system, the respective lens groups move toward the object side with a decreasing spacing between the first lens group and the second lens group, wherein:

• said first lens group consists of, in order from an object side thereof, a first lens component (U1) that has negative refracting power and in which a surface located nearest to an object side thereof is concave on the object side, a second lens component (U2) having positive refracting power, a third lens component (U3) having negative or positive refracting power and a fourth lens component (U4) having positive refracting power, wherein the respective lens components in the first lens group consist of a single lens or a doublet and satisfy the following conditions:
• 0.5<|fG1/f11|<3 (7)−0.4<fG1/f13<0.1 (8)
• where fG1 is a focal length of the first lens group, f11 is a focal length of the first lens component, and f13 is a focal length of the third lens component.

A zoom lens optical system comprising, in order from an object side thereof, a first lens group having positive refracting power and a second lens group having negative refracting power in which, for zooming from a wide-angle end to a telephoto end of the zoom lens optical system, the respective lens groups move toward the object side with a decreasing spacing between the first lens group and the second lens group, wherein:

• said first lens group consists of, in order from an object side thereof, a first lens component (U1) that has negative refracting power and in which a surface located nearest to an object side thereof is concave on the object side, a second lens component (U2) that has positive refracting power and is in a meniscus form convex on an object side thereof, a third lens component (U3) that is a doublet consisting of a negative lens and a positive lens in order from an object side thereof and has negative or positive refracting power and a fourth lens unit (U4) having positive refracting power.