Zoom lens system, optical device with zoom lens system, and method of manufacturing zoom lens system

A zoom lens comprising in order from an object:

• a first lens group having a positive refractive power;
• a second lens group having a negative refractive power;
• and
• a third lens group having a positive refractive power;
• wherein the first lens group has a first-a partial lens group and a first-b partial lens group arranged on an image side of the first-a partial lens group with an air space and is constructed such that the first-b partial lens group moves along an optical axis direction upon focusing from infinity to a close-range object;
• and
• wherein an image-side surface of a lens component arranged closest to an image is distanced from an image plane by at least 10 mm but not more than 30 mm.

A method of manufacturing a zoom lens system, the method comprising the steps of:

• arranging, in order from an object, a first lens group having a positive refractive power and including a first-a partial lens group and a first-b partial lens group arranged on an image side of the first-a partial lens group with an air space, a second lens group having a negative refractive power, and a third lens group having a positive refractive power;
• and
• verifying a focusing action of moving the first-b partial lens group along an optical axis direction, the first-b partial lens group being adapted to focus from infinity to a close-range object;
• wherein the third lens group comprises a third-a partial lens group and a third-b partial lens group arranged on the image side of the third-a partial lens group with an air space;
• wherein the third-a partial lens group in the third lens group has a positive refractive power;
• wherein the third-b partial lens group in the third lens group has a negative refractive power;
• and
• wherein the following conditional expression is satisfied:
• 1.8<f1/fw<2.6
• where f1 denotes a focal length of the first lens group, and fw denotes a focal length of the whole system at a wide angle end state.

A method of manufacturing a zoom lens system, the method comprising the steps of:

• arranging, in order from an object, a first lens group having a positive refractive power and including a first-a partial lens group and a first-b partial lens group arranged on an image side of the first-a partial lens group with an air space, a second lens group having a negative refractive power, and a third lens group having a positive refractive power;
• and
• verifying a focusing action of moving the first-b partial lens group along an optical axis direction, the first-b partial lens group being adapted to focus from infinity to a close-range object;
• wherein an image-side surface of a lens component arranged closest to the image is distanced from an image plane by at least 10 mm but not more than 30 mm.