Zoom lens

A wide-angle zoom lens comprising in the following order from the object side:

• a first lens group having a positive refractive power and front and rear lens subgroups, a lens closest to the object side in said first lens group being a negative lens;
• and
• a second lens group having a negative refractive power,
• wherein an air gap between said first and second lens groups decreases upon zooming from a wide-angle end to a telephoto end, and said zoom lens satisfies the following conditions:
• 0.09.ltoreq.D2/fW.ltoreq.0.4
• -0.6.ltoreq.Q1.ltoreq.0.5
• where fW is the focal length of the entire zoom lens at the wide-angle end, D2 is the air gap between said front and rear lens subgroups, and Q1 is the shape factor of said negative lens, the shape factor Q1 being defined by Q1=(R2+R1)/(R2-R1), where R1 is the radius of curvature of an object-side lens surface of said negative lens, and R2 is the radius of curvature of an image-side lens surface of said negative lens.

A wide-angle zoom lens comprising in the following order from the object side:

• a first lens group having a positive refractive power, said first lens group consisting of, in the following order from the object side, a front lens subgroup which includes at least one negative lens, and a rear lens subgroup which includes at least one positive lens and at least one negative lens, and an air gap between said front and rear lens subgroups being largest of air gaps in said first lens group;
• and
• a second lens group having a negative refractive power,
• wherein an air gap between said first and second lens groups decreases upon zooming from a wide-angle end to a telephoto end, and said zoom lens satisfies the following conditions:
• 0.09.ltoreq.D2/fW.ltoreq.0.4
• -0.6.ltoreq.Q1.ltoreq.0.5
• where fW is the focal length of the entire zoom lens at the wide-angle end, D2 is the air gap between said front and rear lens subgroups, and Q1 is the shape factor of said negative lens in said front lens subgroup, the shape factor Q1 being defined by Q1=(R2+R1)/(R2-R1), where R1 is the radius of curvature of an object-side lens surface of said negative lens in said front lens subgroup, and R2 is the radius of curvature of an image-side lens surface of said negative lens in said front lens subgroup.

A wide-angle zoom lens comprising in the following order from the object side:

• a first lens group having a positive refractive power, said first lens group consisting of, in the following order from the object side, a first lens component of a negative refractive power, a second lens component of a positive refractive power, a third lens component of a positive or negative refractive power, and a fourth lens component of a positive refractive power;
• and
• a second lens group having a negative refractive power,
• wherein an air gap between said first and second lens groups decreases upon zooming from a wide-angle end to a telephoto end, and said zoom lens satisfies the following conditions:
• 0<f1/fL2<2.5
• 0.5<f1/fL4<2.0
• D/f1<0.84
• 0.085<DL3/fW<0,400
• where f1 is the focal length of said first lens group, fL2 is the focal length of said second lens component in said first lens group, fL4 is the focal length of said fourth lens component in said first lens group, and D is the on-axis distance from a lens surface closest to the object side to a lens surface closest to the image side in said first lens group, fW is the focal length of said wide-angle zoom lens at a wide-angle end, and DL3 is the on-axis lens thickness of said third lens component.

A zoom lens comprising in the following order from the object side:

• a first lens group having a positive refractive power, said first lens group comprising a cemented lens consisting of three lens elements, and at least one negative lens disposed at the object side of said cemented lens;
• and
• a second lens group having a negative refractive power,
• wherein an air gap between said first and second lens groups decreases upon zooming from a wide-angle end to a telephoto end, and
• wherein said zoom lens satisfies the following conditional formulas:
• 0.50.ltoreq.f1/fW.ltoreq.0.95
• -1.5.ltoreq.f2/fW.ltoreq.-0.4
• where fW is the focal length of said zoom lens at the wide-angle end, f1 is the focal length of said first lens group, and f2 is the focal length of said second lens group.

A zoom lens comprising in the following order from the object side:

• a first lens group having a positive refractive power, said first lens group comprising, in the following order from the object side, a front lens subgroup which has a negative refractive power and comprises at least one negative lens, and a rear lens subgroup which has a positive refractive power and has at least one positive lens;
• and
• a second lens group having a negative refractive power,
• wherein an air gap between said first and second lens groups decreases upon zooming from a wide-angle end to a telephoto end, and only said rear lens subgroup is moved in an object direction along an optical axis upon focusing from a far distance end to a near distance end.

A wide-angle zoom lens with an angle of field exceeding 70.degree. at a wide-angle end and comprising in the following order from the object side:

• a first lens group having a positive refractive power, said first lens group consisting of, in the following order from the object side, a first lens component of a negative refractive power, a second lens component of a positive refractive power, a third lens component of a positive or negative refractive power, and a fourth lens component of a positive refractive power;
• and
• a second lens group having a negative refractive power,
• wherein an air gap between said first and second lens groups decreases upon zooming from the wide-angle end to a telephoto end, and said zoom lens satisfies the following conditions:
• 0<f1/fL2<2.5
• 0.5<f1/fL4<2.0
• D/f1<0.84
• where f1 is the focal length of said first lens group, fL2 is the focal length of said second lens component in said first lens group, fL4 is the focal length of said fourth lens component in said first lens group, and D is the on-axis distance from a lens surface closest to the object side to a lens surface closest to the image side in said first lens group.