CPC G02B 15/144113 (2019.08) [G02B 13/009 (2013.01); G02B 7/021 (2013.01); G03B 5/02 (2013.01); G03B 2205/0046 (2013.01); G03B 2205/0069 (2013.01)] | 19 Claims |
1. An optical system, comprising, successively from an object side to an image side:
a first lens unit having positive refractive power;
a second lens unit having negative refractive power;
a third lens unit having positive refractive power; and
a fourth lens unit having positive refractive power;
wherein positions of the first lens unit and the fourth lens unit are fixed with respect to an imaging surface of the optical system, the second lens unit and the third lens unit are movable with respect to the first lens unit along an optical axis direction of the optical system, when the optical system is zoomed from a short focal end to a long focal end, a distance between the first lens unit and the second lens unit increases, and a distance between the third lens unit and the fourth lens unit also increases;
wherein the optical system satisfies the following condition:
wherein g1 is a distance between a lens surface closest to the object side and a lens surface closest to the image side in the first lens unit on the optical axis, g2 is a distance between a lens surface closest to the object side and a lens surface closest to the image side in the second lens unit on the optical axis, g3 is a distance between a lens surface closest to the object side and a lens surface closest to the image side in the third lens unit on the optical axis, g4 is a distance between a lens surface closest to the object side and a lens surface closest to the image side in the fourth lens unit on the optical axis, and fd is the focal length of the optical system at the short focal end.
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