Zoom lens

A zoom lens constructed by two lens groups in which a first lens group having a positive focal length is arranged on an object side and a second lens group having a negative focal length is arranged on an image side and a zooming operation is performed by changing a distance between said first and second lens groups;

• the first lens group having first to fourth lenses sequentially arranged from the object side toward the image side;
• the first lens being constructed by a positive meniscus lens having a convex face directed onto the object side;
• the second lens being constructed by a biconcave lens;
• the third lens being constructed by a positive lens;
• and
• the fourth lens being constructed by a biconvex lens;
• the second lens group having fifth to seventh lenses sequentially arranged from the object side toward the image side;
• the fifth lens being constructed by a positive meniscus lens having a convex face directed onto the image side;
• the sixth lens being constructed by a negative meniscus lens having a convex face directed onto the image side;
• and
• the seventh lens being constructed by a negative meniscus lens having a convex face directed onto the image side;
• an image side lens face of the fourth lens being constructed by an aspherical surface;
• and
• a focal length f.sub.T of an entire lens system at a long focal point end thereof, a focal length f.sub.1 of the first lens group and a focal length f.sub.2 of the second lens group satisfying the following conditions,
• 0.26<f.sub.1 /f.sub.T <0.29 (3-1)
• f.sub.2 /f.sub.1 >-1.0. (3-2)

A zoom lens constructed by two lens groups in which a first lens group having a positive focal length is arranged on an object side and a second lens group having a negative focal length is arranged on an image side and a zooming operation is performed by changing a distance between said first and second lens groups;

• the first lens group having first to fourth lenses sequentially arranged from the object side toward the image side;
• the first lens being constructed by a positive meniscus lens having a convex face directed onto the object side;
• the second lens being constructed by a biconcave lens;
• the third lens being constructed by a positive lens;
• and
• the fourth lens being constructed by a biconvex lens;
• the second lens group having fifth to seventh lenses sequentially arranged from the object side toward the image side;
• the fifth lens being constructed by a positive meniscus lens having a convex face directed onto the image side;
• the sixth lens being constructed by a negative meniscus lens having a convex face directed onto the image side;
• and
• the seventh lens being constructed by a negative meniscus lens having a convex face directed onto the image side;
• each of image side lens faces of the fourth and fifth lenses being constructed by an aspherical surface;
• and
• a focal length f.sub.T of an entire lens system at a long focal point end thereof, a focal length f.sub.1 of the first lens group and a focal length f.sub.2 of the second lens group satisfying the following conditions,
• 0.25<f.sub.1 /f.sub.T <0.28 (1-1)
• f.sub.2 /f.sub.1 >-0.95. (1-2)

A zoom lens constructed by two lens groups in which a first lens group having a positive focal length is arranged on an object side and a second lens group having a negative focal length is arranged on an image side and a zooming operation is performed by changing a distance between said first and second lens groups;

• the first lens group having first to fourth lenses sequentially arranged from the object side toward the image side;
• the first lens being constructed by a positive meniscus lens having a convex face directed onto the object side;
• the second lens being constructed by a biconcave lens;
• the third lens being constructed by a positive lens;
• and
• the fourth lens being constructed by a biconvex lens;
• the second lens group having fifth to seventh lenses sequentially arranged from the object side toward the image side;
• the fifth lens being constructed by a positive meniscus lens having a convex face directed onto the image side;
• the sixth lens being constructed by a negative meniscus lens having a convex face directed onto the image side;
• and
• the seventh lens being constructed by a negative meniscus lens having a convex face directed onto the image side;
• each of an image side lens face of the fourth lens, and object and image side lens faces of the fifth lens being constructed by an aspherical surface;
• and
• a focal length f.sub.T of an entire lens system at a long focal point end thereof, a focal length f.sub.1 of the first lens group and a focal length f.sub.2 of the second lens group satisfying the following conditions,
• 0.24<f.sub.1 /f.sub.T <0.27 (13-1)
• f.sub.2 /f.sub.1 >-0.90. (13-2)

A zoom lens constructed by two lens groups in which a first lens group having a positive focal length is arranged on an object side and a second lens group having a negative focal length is arranged on an image side and a zooming operation is performed by changing a distance between said first and second lens groups;

• the first lens group having a first lens, a joining lens and a fourth lens sequentially arranged from the object side toward the image side;
• the first lens being constructed by a positive meniscus lens having a convex face directed onto the object side;
• the joining lens being constructed by a second lens as a biconcave lens and a third lens as a biconvex lens;
• and
• the fourth lens being constructed by a biconvex lens;
• the second lens group having fifth to seventh lenses sequentially arranged from the object side toward the image side;
• the fifth lens being constructed by a positive meniscus lens having a convex face directed onto the image side;
• the sixth lens being constructed by a negative meniscus lens having a convex face directed onto the image side;
• and
• the seventh lens being constructed by a negative meniscus lens having a convex face directed onto the image side;
• a combined focal length f.sub.W of an entire lens system at a short focal point end thereof, a combined focal length f.sub.T of the entire lens system at a long focal point end thereof, a focal length f.sub.1 of the first lens group, a focal length f.sub.2 of the second lens group, a thickness d.sub.3 of the second lens on an optical axis of the lens system, and a thickness d.sub.4 of the third lens on the optical axis of the lens system satisfying the following conditions,
• 0.24<f.sub.1 /f.sub.T <0.28 (20-1)
• f.sub.2 /f.sub.1 >-0.95 (1-2)
• (d.sub.3 +d.sub.4)/f.sub.W >0.26. (20-3)