Zoom lens system and optical apparatus using the same

A zoom lens system comprising, in order from an object side:

• a first lens unit of positive refractive power;
• a second lens unit of negative refractive power that moves along the optical axis for zooming;
• a third lens unit of positive refractive power including, in order from the object side, a first lens subunit of positive refractive power consisting of one or two positive lens elements facing to the object side a convex surface of refractive power that is stronger at the object side than an image side, and a second lens subunit including a cemented lens coupling a concave surface of a negative lens element of refractive power that is stronger at the image side than at the object side, with a convex surface of a positive lens element of refractive power that is stronger at the object side than at the image side;
• and
• a fourth lens unit of positive refractive power,
• wherein a condition 0.09<Dab/f3<0.35 is satisfied where Dab is a separation between the first lens subunit and the second lens subunit, and f3 is a focal length of said third lens unit.

A zoom lens system comprising, in order from an object side:

• a first lens unit of positive refractive power;
• a second lens unit of negative refractive power that moves along the optical axis for zooming;
• a third lens unit of positive refractive power including, in order from the object side, a first lens subunit of positive refractive power consisting of one or two positive lens elements facing to the object side a convex surface of refractive power that is stronger at the object side than an image side, and a second lens subunit including a cemented lens coupling a concave surface of a negative lens element of refractive power stronger at the image side, with a convex surface of a positive lens element of refractive power stronger at the object side;
• and
• a fourth lens unit of positive refractive power,
• wherein a condition 1.67<3G1n<1.89 is satisfied where 3G1 is one of positive lens element with an aspherical surface among the first lens subunit, and 3G1n is a refractive index of a material of the positive lens element assigned to 3G1.

A zoom lens system comprising, in order from an object side:

• a first lens unit of positive refractive power;
• a second lens unit of negative refractive power that moves along the optical axis for zooming, said second lens unit including, in order from the object side, a first negative lens element, a second negative lens element, a third positive lens element, and a fourth negative lens element;
• a third lens unit of positive refractive power;
• and
• a fourth lens unit of positive refractive power,
• wherein conditions 0.81<2G1f/f2<1.25, 20.5<2Glν<37.5, and 0.21<2G1f/2G2f<0.81 are satisfied where 2G1f is a focal length of the first negative lens element, 2G2f is a focal length of the second negative lens element, f2 is a focal length of said second lens unit, 2Glν is Abbe number of a material of the first negative lens element.

A zoom lens system comprising, in order from an object side:

• a first lens unit of positive refractive power;
• a second lens unit of negative refractive power that moves along the optical axis for zooming;
• a third lens unit of positive refractive power including, in order from the object side, a first lens subunit of positive refractive power consisting of one or two positive lens elements facing to the object side a convex surface, and a second lens subunit including a cemented lens coupling a negative lens element facing a concave surface thereof to the image side, with a positive lens element facing a convex surface thereof to the object side;
• and
• a fourth lens unit of positive refractive power,
• wherein conditions 0.09<Dab/f3<0.35, 0.5<f3/f4<1.25, 0.34<(3G3R2+3G3R1)/(3G3R2−3G3R1)<1.34, and −0.25<3af/3bf<0.35 are satisfied where Dab is a separation between the first lens subunit and the second lens subunit at the object side, f3 and f4 are focal lengths of said third and fourth lens units, respectively, 3af and 3bf are focal lengths of the first and second lens subunits, respectively, and 3G3R1 and 3G3R2, respectively, are paraxial radiuses of curvature on surfaces at the object and image sides of the positive lens element that constitutes the cemented lens of said second lens subunit.

A zoom lens system comprising, in order from an object side:

• a first lens unit of positive refractive power that doesn't move along an optical axis for zooming;
• a second lens unit of negative refractive power that moves along the optical axis for zooming;
• a third lens unit of positive refractive power including, in order from the object side, a first lens subunit of positive refractive power having a positive lens element facing a convex surface thereof to the object side, a stop, and a second lens subunit including a cemented lens coupling a negative lens element facing a concave surface thereof to the image side, with a positive lens element facing a convex surface thereof to the object side;
• and
• a fourth lens unit of positive refractive power.

A zoom lens system comprising, in order from an object side:

• a first lens unit of positive refractive power;
• a second lens unit of negative refractive power;
• a third lens unit of positive refractive power including, in order from the object side, a first lens subunit of positive refractive power having a positive lens element facing a convex surface thereof to the object side, a stop, and a second lens subunit including a cemented lens coupling a negative lens element facing a concave surface thereof to the image side, with a positive lens element facing a convex surface thereof to the object side;
• and
• a fourth lens unit of positive refractive power,
• wherein a condition 0.08<Dab/f3<0.64 is satisfied where Dab is a separation between said first and second lens subunits, and f3 is a focal length of said third lens unit.

A zoom lens system comprising, in order from an object side:

• a first lens unit of positive refractive power;
• a second lens unit of negative refractive power;
• a third lens unit of positive refractive power including, in order from the object side, a first positive lens element having an aspherical surface facing a convex surface thereof to the object side, a stop, and a negative lens element facing a concave surface thereof to the image side, and a second positive lens element facing a convex surface thereof to the object side;
• and
• a fourth lens unit of positive refractive power,
• wherein a condition 1.67<3G1n<1.89 is satisfied where 3G1n is a refractive index of a material of the first positive lens element in said third lens unit.