Variable magnification optical system, imaging apparatus, and method for manufacturing variable magnification optical system

A variable magnification optical system comprising, in order from an object side along an optical axis, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group;

• upon zooming from a wide angle end state to a telephoto end state, the first lens group, the second lens group, the third lens group and the fourth lens group being moved along the optical axis, respectively;
• the first lens group comprising one negative lens and one positive lens;
• the third lens group comprising, in order from the object side along the optical axis, a 3a-th lens group having positive refractive power, an aperture, and a 3b-th lens group having positive refractive power;
• the 3b-th lens group comprising at least one negative lens component;
• and
• the conditions of the following expressions being satisfied:
• |f3a/f4|<1.00
• 0.700<(−f3bn)/f3a<1.500
• where f3a denotes a focal length of the 3a-th lens group, f4 denotes a focal length of the fourth lens group, and f3bn denotes a focal length of the negative lens component on the most image side within the 3b-th lens group.

A method for manufacturing a variable magnification optical system comprising, in order from an object side along an optical axis, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group;

• the method comprising:
• constructing, upon zooming from a wide angle end state to a telephoto end state, the first lens group, the second lens group, the third lens group and the fourth lens group to be moved along the optical axis, respectively;
• arranging the first lens group to comprise one negative lens and one positive lens;
• arranging the third lens group to comprise, in order from the object side along the optical axis, a 3a-th lens group having positive refractive power, an aperture, and a 3b-th lens group having positive refractive power;
• and
• constructing so as to satisfy the conditions of the following expressions:
• |f3a/f4|<0.540
• |f3b/f4|<1.00
• where f3a denotes a focal length of the 3a-th lens group, f4 denotes a focal length of the fourth lens group, and f3b denotes a focal length of the 3b-th lens group.

A method for manufacturing a variable magnification optical system comprising, in order from an object side along an optical axis, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group;

• the method comprising:
• constructing, upon zooming from a wide angle end state to a telephoto end state, the first lens group, the second lens group, the third lens group and the fourth lens group to be moved along the optical axis, respectively;
• arranging the first lens group to comprise one negative lens and one positive lens;
• arranging the third lens group to comprise, in order from the object side along the optical axis, a 3a-th lens group having positive refractive power, an aperture, and a 3b-th lens group having positive refractive power;
• arranging the 3b-th lens group to include at least one negative lens component;
• and
• constructing so as to satisfy the conditions of the following expressions:
• |f3a/f4|<1.00
• 0.700<(−f3bn)/f3a<1.500
• where f3a denotes a focal length of the 3a-th lens group, f4 denotes a focal length of the fourth lens group, and f3bn denotes a focal length of the negative lens component on the most image side within the 3b-th lens group.