CPC G02B 15/142 (2019.08) [G02B 27/005 (2013.01); G02B 27/646 (2013.01)] | 30 Claims |
1. An optical system comprising, in order from an object side to an image side:
a first lens unit having a positive refractive power;
a first focus lens unit having a negative refractive power; and
a second focus lens unit having a positive refractive power,
wherein the first lens unit is fixed during focusing,
wherein the first focus lens unit and the second focus lens unit move so that a distance between the first focus lens unit and the second focus lens unit changes during focusing,
wherein the first lens unit includes a single lens which is disposed closest to an object and has a negative refractive power, and
wherein the following inequality is satisfied:
2.20<ff2/bf<12.00
where ff2 is a focal length of the second focus lens unit, and bf is a back focus of the optical system.
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