CPC G02B 15/1465 (2019.08) [G02B 3/04 (2013.01)] | 20 Claims |
1. A magnification-variable optical system comprising:
a first lens group having negative refractive power; 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 consists of, sequentially from the object side, a negative single lens, a negative single lens, a negative single lens, and a positive single lens, and
the following conditional expressions are satisfied:
−4.00<(L1r2+L1r1)/(L1r2−L1r1)<−0.50
100.00°<2ωw
1.42<(−f1)/fw<2.00
1.314≤fL1/f1<2.00
0.058≤(L3r2+L3r1)/(L3r2−L3r1)<0.80
where
L1r1: radius of curvature of a lens surface of a lens closest to an object side in the first lens group, the lens surface being on the object side,
L1r2: radius of curvature of a lens surface of the lens closest to the object side in the first lens group, the lens surface being on an image side,
2ωw: full angle of view of the magnification-variable optical system in a wide-angle state,
fw: focal length of the magnification-variable optical system in the wide-angle state,
f1: focal length of the first lens group,
fL1: focal length of the lens closest to the object side in the first lens group,
L3r1: radius of curvature of a lens surface of a lens third closest to the object side in the first lens group, the lens surface being on the object side, and
L3r2: radius of curvature of a lens surface of the lens third closest to the object side in the first lens group, the lens surface being on the image side.
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