Optical system and imaging apparatus

An optical system comprising:

• a first lens group;
• and
• a rear group that has a plurality of lens groups,
• the first lens group and the rear group being arranged in order from an object side, wherein
• the rear group includes a first focus group which has a negative refractive power and moves during focusing, and a second focus group which has a negative refractive power and moves during focusing,
• at least one lens group P having a positive refractive power is provided between the first focus group and the second focus group,
• the lens group P includes a subgroup PN having a negative refractive power at a position closest to the object side, and
• following formulae are satisfied:
• 0.3
• <
• ❘
• "\[LeftBracketingBar]"
• fP
• /
• fPN
• ❘
• "\[RightBracketingBar]"
• (
• 1
• )
• 0.05
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• ❘
• "\[LeftBracketingBar]"
• (
• 1
• -
• β
• ⁢
• f
• ⁢
• 1
• ×
• β
• ⁢
• f
• ⁢
• 1
• )
• ×
• β
• ⁢
• f
• ⁢
• 1
• ⁢
• r
• ×
• β
• ⁢
• f
• ⁢
• 1
• ⁢
• r
• /
• Fno
• <
• 2.
• (
• 2
• )
• here,
• fP is a focal length of the lens group P,
• fPN is a focal length of the subgroup PN,
• βf1 is a lateral magnification of the first focus group at infinity focus,
• βf1r is a lateral magnification at infinity focus of all lenses arranged on an image side of the first focus group, and
• Fno is an open F-number of the optical system at infinity focus.