Zoom lens with an anamorphic converter

A zoom lens having lens groups arranged along an optical axis from an object side to an image side, comprising:

• a first lens group nearest the object side having positive refractive power and being fixed along the optical axis;
• a second lens group, nearer to the image side than the first lens group, having negative refractive power and being movable along the optical axis when the zoom lens shifts from a maximum wide-angle state to a maximum telephoto state;
• a third lens group nearer to the image side than the second lens group and having one of positive or negative refractive power;
• a fourth lens group nearer to the image side than the third lens group and having positive refractive power;
• a fifth lens group nearest the image side having positive refractive power;
• and
• an anamorphic converter lens group having a first magnification within a specified plane, including the optical axis and a second magnification within a plane intersecting perpendicularly to the specified plane, wherein the anamorphic converter lens group is freely attachable and detachable in the optical path between the fourth lens group and the fifth lens group, the anamorphic converter lens group comprising,
• a front group nearest the object side with negative refractive power within the specified lane,
• a rear group nearer the image side with positive refractive power within the specified plane, and
• at least a cemented lens in at least one of the rear group and the front group, wherein the anamorphic converter lens group has an angle magnification .gamma. wherein 0.5<.gamma.<1.0, and wherein the zoom lens satisfies 0.3<.vertline.f1/f2.vertline..sup.-1/2 <0.9, in which f1 is the focal length of the first lens group and f2 is the focal length of the said second lens group, and at least one lens surface is aspherical in shape in at least one of the lens groups, wherein the anamorphic converter lens group has negative composite refractive power within the specified plane, when an exit pupil of said zoom lens in the state in which the anamorphic converter lens group is released is positioned closer to the object side than the image side, and has a positive composite refractive power within the specified plane, when the exit pupil of said zoom lens in the state in which said anamorphic converter lens group is released is positioned nearer the image side than the object side.

A zoom lens having lens groups arranged along an optical axis from an object side to an image side, comprising:

• a first lens group nearest the object side having positive refractive power and being fixed along the optical axis;
• a second lens group nearer to the image side than the first lens group having negative refractive power and being movable along the optical axis when the zoom lens shifts from a maximum wide-angle state to a maximum telephoto state;
• a third lens group nearer to the image side than the second lens group having one of positive or negative refractive power;
• a fourth lens group nearer to the image side than the third lens group having positive refractive power wherein at least part of the fourth lens group is movable along the optical axis in order to correct movement of an image plane in accordance with magnification;
• a fifth lens group nearest the image side having positive refractive power;
• and
• an anamorphic converter lens group having a first magnification within a specified plane including the optical axis and a second magnification within a plane intersecting perpendicularly with the specified plane, wherein the anamorphic converter lens group is freely attachable and detachable in the optical path between said fourth lens group and said fifth lens group, wherein the anamorphic converter lens group comprises,
• a front group nearest the object side with negative refractive power within the specified plane,
• a rear lens group nearer the image side with positive refractive power within said specified plane, and
• at least a cemented lens within at least one of the front group and the rear group, wherein an angle magnification .gamma. of the said anamorphic converter lens group satisfies 0.5<.gamma.<1.0,
• wherein the zoom lens satisfies 0.3<f1/f2.vertline..sup.-1/2 <0.9, in which f1 is a focal length of the first lens group and f2 is a focal length of the second lens group,
• wherein the anamorphic converter lens group has negative composite refractive power within the specified plane when an exit pupil of said zoom lens in the state in which said anamorphic converter lens group is released is positioned closer to the object side than the image side and has a positive composite refractive power within the specified plane when an exit pupil of the zoom lens in the state in which the anamorphic converter lens group is released is positioned nearer the image side than the object side.

A zoom lens having lens groups arranged along an optical axis from an object side to an image side, comprising:

• a first lens group nearest the object side having positive refractive power and being fixed along the optical axis;
• a second lens group nearer to the image side than the first lens group having negative refractive power and being movable along the optical axis when the zoom lens shifts from a maximum wide-angle state to a maximum telephoto state;
• a third lens group nearer to the image side than the second lens group having one of positive or negative refractive power;
• a fourth lens group nearer to the image side than the third lens group having positive refractive power;
• a fifth lens group having positive refractive power wherein all or a part of said fifth lens group is movable along the optical axis in order to correct movement of the image plane in accordance with magnification;
• and
• an anamorphic converter lens group having a first magnification within a specified plane including the optical axis and a second magnification within a plane intersecting perpendicularly with the specified plane wherein the anamorphic converter lens group is freely attachable and detachable in the optical path between the fourth lens group and the fifth lens group wherein the anamorphic converter lens group comprises,
• a front group nearest the object side with negative refractive power within the specified plane,
• a rear group nearer the image side with positive refractive power within said specified plane, and
• at least a cemented lens within at least one of the rear group and the front group, wherein an angle magnification .gamma. of the said anamorphic converter lens group satisfies 0.5<.gamma.<1.0,
• wherein the zoom lens satisfies 0.3<.vertline.f1/f2.vertline..sup.-1/2 <0.9, in which f1 is a focal length of the first lens group and f2 is a focal length of the second lens group, and
• wherein the anamorphic converter lens group has negative composite refractive power within the specified plane when an exit pupil of the zoom lens in the state in which said anamorphic converter lens group is released is positioned closer to the object side than the image side and a positive composite refractive power within the specified plane when the exit pupil of the zoom lens in the state in which said anamorphic converter lens group is released is positioned nearer the image side than the object side.