Variable magnification imaging optical system

A variable magnification imaging optical system comprising in order from an object side, a first front lens group GF1 consisting of one or two lens groups and having a positive refractive power as a whole, a second front lens group GF2 consisting of one or more lens groups and having a negative refractive power as a whole, a middle group GM consisting of one or more lens groups, and a subsequent group GR,

• wherein the first front lens group GF1 has a first lens group G1 at a position closest to the object side, an aperture diaphragm S is disposed closer to an image side than the second front lens group GF2, the second front lens group GF2 has a lens group having a strongest negative refractive power among lens groups disposed closer to the object side than an aperture diaphragm S, distances between adjacent lens groups change during magnification change or focusing, and during magnification change from a wide-angle end to a telephoto end (in a case of focusing on an infinite distance object), a lens group having a largest negative refractive power among lens groups constituting the second front lens group GF2 moves to the image side, and the following conditional expressions are satisfied:
• 2.5
• <
• fT
• /
• fF
• ⁢
• 1
• <
• 11.
• (
• 1
• )
• 0.15
• <
• LiT
• /
• fT
• <
• 0.7
• (
• 2
• )
• where:
• fT:
• focal length of entire system at telephoto end at infinity
• fF1:
• focal length of the first front lens group GF1 at telephoto end at infinity
• LiT:
• length on optical axis from a lens surface closest to object side at telephoto end at infinity to image surface.