Magnification-variable optical system, optical apparatus, and method for manufacturing magnification-variable optical system

A magnification-variable optical system comprising:

• a first lens group having negative refractive power and including, sequentially from an object side, a negative lens, a negative lens, a negative lens, and a positive lens;
• and
• a rear group including at least one lens group disposed on an image side of the first lens group, wherein
• a distance between lens groups adjacent to each other changes at magnification change,
• the first lens group moves in an optical axis direction at magnification change, and
• the following conditional expressions are satisfied:
• 80.00<v1n
• N1n≤3
• 0.40<STLw/TLw<0.70
• where
• v1n:
• Abbe number of a medium of at least one negative lens included in the first lens group at a d line,
• N1n:
• number of negative lenses included in the first lens group,
• TLw:
• total length of the magnification-variable optical system in a wide-angle state, and
• STLw:
• distance on an optical axis from a lens surface closest to an object side to an aperture stop in the magnification-variable optical system in the wide-angle state.

A method for manufacturing a magnification-variable optical system including a first lens group and a rear group, the first lens group having negative refractive power and including, sequentially from an object side, a negative lens, a negative lens, a negative lens, and a positive lens, the rear group including at least one lens group disposed on an image side of the first lens group, the method for manufacturing the magnification-variable optical system comprising:

• disposing the lens groups so that a distance between lens groups adjacent to each other changes at magnification change;
• disposing the lens groups so that the first lens group moves in an optical axis direction at magnification change;
• and
• disposing the lens groups so that the following conditional expressions are satisfied:
• 80.00<v1n
• N1n≤3
• 0.40<STLw/TLw<0.70
• where
• v1n:
• Abbe number of a medium of at least one negative lens included in the first lens group at a d line,
• N1n:
• number of negative lenses included in the first lens group,
• TLw:
• total length of the magnification-variable optical system in a wide-angle state, and
• STLw:
• distance on an optical axis from a lens surface closest to an object side to an aperture stop in the magnification-variable optical system in the wide-angle state.